Kerry Hourigan

Measurement of instantaneous velocity and surface topography in the wake of a cylinder at low Reynolds number

Publisher: Elsevier BV

Date: 11-2008

DOI: 10.1016/J.JFLUIDSTRUCTS.2008.06.013

Common variants in the HLA-DRB1–HLA-DQA1 HLA class II region are associated with susceptibility to visceral leishmaniasis

Publisher: Springer Science and Business Media LLC

Date: 06-01-2013

DOI: 10.1038/NG.2518

Control of vortex breakdown in a closed cylinder with a small rotating rod

Publisher: Elsevier BV

Date: 11-2008

DOI: 10.1016/J.JFLUIDSTRUCTS.2008.06.015

Motion of a Möbius band in free fall

Publisher: Elsevier BV

Date: 05-2009

DOI: 10.1016/J.JFLUIDSTRUCTS.2009.04.007

The inner and outer solutions to the inertial flow over a rolling circular cylinder

Publisher: Cambridge University Press (CUP)

Date: 04-05-2023

DOI: 10.1017/JFM.2023.296

Abstract: This paper proposes a new approach for evaluating numerically the forces and moments applied to a circular cylinder that is immersed in a fluid and which translates and rotates near a plane wall. Under the proposed approach, the flow is decomposed into inner and outer flows. The inner flow represents the flow in the thin interstice between the cylinder and the wall, and is obtained as an analytic expression using lubrication theory. The outer flow represents the flow far from the interstice, which does not depend on the magnitude of the gap between the cylinder and the wall, when the gap is small. The outer flow is obtained using numerical simulation as a function of both the Reynolds number and the slip coefficient. The force and moment coefficients are then obtained, as functions of the Reynolds number, slip coefficient and gap-to-diameter ratio, by combining the inner and outer solutions. Importantly, since the outer flow does not depend on the gap-to-diameter ratio, the parameter space to be explored by numerical simulations is greatly reduced compared to using finite gap ratio simulations. Moreover, the numerical difficulties associated with resolving the interstitial flow are avoided. The proposed approach can be extended to a wide range of rolling bodies, including spherical particles and wheels, and should significantly reduce the computational expense required to model the hydrodynamic forces and predict the subsequent motion of such bodies.

Cardiogenesis of Embryonic Stem Cells with Liquid Marble Micro‐Bioreactor

Publisher: Wiley

Date: 12-05-2014

DOI: 10.1002/ADHM.201400138

Abstract: A liquid marble micro-bioreactor is prepared by placing a drop of murine embryonic stem cell (ESC) (Oct4B2-ESC) suspension onto a polytetrafluoroethylene (PTFE) particle bed. The Oct4B2-ESC aggregates to form embryoid bodies (EBs) with relatively uniform size and shape in a liquid marble within 3 d. For the first time, the feasibility of differentiating ESC into cardiac lineages within liquid marbles is being investigated. Without the addition of growth factors, suspended EBs from liquid marbles express various precardiac mesoderm markers including Flk-1, Gata4, and Nkx2.5. Some of the suspended EBs exhibit spontaneous contraction. These results indicate that the liquid marble provides a suitable microenvironment to induce EB formation and spontaneous cardiac mesoderm differentiation. Some of the EBs are subsequently plated onto gelatin-coated tissue culture dishes. Plated EBs express mature cardiac markers atrial myosin light chain 2a (MLC2a) and ventricular myosin light chain (MLC2v), and the cardiac structural marker α-actinin. More than 60% of the plated EBs exhibit spontaneous contraction and express mature cardiomyocyte marker cardiac troponin T (cTnT), indicating that these EBs have differentiated into functional cardiomyocytes. Together, these results demonstrate that the liquid-marble technique is an easily employed, cost effective, and efficient approach to generate EBs and facilitating their cardiogenesis.

From spheres to circular cylinders: non-axisymmetric transitions in the flow past rings

Publisher: Cambridge University Press (CUP)

Date: 10-05-2004

DOI: 10.1017/S0022112004008614

Vortex-induced vibration of a neutrally buoyant tethered sphere

Publisher: Cambridge University Press (CUP)

Date: 19-02-2013

DOI: 10.1017/JFM.2012.634

Abstract: A combined numerical and experimental study examining vortex-induced vibration (VIV) of a neutrally buoyant tethered sphere has been undertaken. The study covered the Reynolds-number range $50\\leq \\mathit{Re}\\lesssim 12\\hspace{0.167em} 000$ , with the numerical ( $50\\leq \\mathit{Re}\\leq 800$ ) and experimental ( $370\\leqslant \\mathit{Re}\\lesssim 12\\hspace{0.167em} 000$ ) ranges overlapping. Neutral buoyancy was chosen to eliminate one parameter, i.e. the influence of gravity, on the VIV behaviour, although, of course, the effect of added mass remains. The tether length was also chosen to be sufficiently long so that, to a good approximation, the sphere was constrained to move within a plane. Seven broad but relatively distinct sphere oscillation and wake states could be distinguished. For regime I, the wake is steady and axisymmetric, and it undergoes transition to a steady two-tailed wake in regime II at $\\mathit{Re}= 210$ . Those regimes are directly analogous to those of a fixed sphere. Once the sphere begins to vibrate at $\\mathit{Re}\\simeq 270$ in regime III, the wake behaviour is distinct from the fixed-sphere wake. Initially the vibration frequency of the sphere is half the shedding frequency in the wake, with the latter consistent with the fixed-sphere wake frequency. The sphere vibration is not purely periodic but modulated over several base periods. However, at slightly higher Reynolds numbers ( $\\mathit{Re}\\simeq 280$ ), planar symmetry is broken, and the vibration shifts to the planar normal (or azimuthal) direction, and becomes completely azimuthal at the start of regime IV at $\\mathit{Re}= 300$ . In comparison, for a fixed sphere, planar symmetry is broken at a much higher Reynolds number of $\\mathit{Re}\\simeq 375$ . Interestingly, planar symmetry returns to the wake for $\\mathit{Re}\\gt 330$ , in regime V, for which the oscillations are again radial, and is maintained until $\\mathit{Re}= 450$ or higher. At the same time, the characteristic vortex loops in the wake become symmetrical, i.e. two-sided. For $\\mathit{Re}\\gt 500$ , in regime VI, the trajectory of the sphere becomes irregular, possibly chaotic. That state is maintained over the remaining Reynolds-number range simulated numerically ( $\\mathit{Re}\\leq 800$ ). Experiments overlapping this Reynolds-number range confirm the litude radial oscillations in regime V and the chaotic wandering for regime VI. At still higher Reynolds numbers of $\\mathit{Re}\\gt 3000$ , in regime VII, the trajectories evolve to quasi-circular orbits about the neutral point, with the orbital radius increasing as the Reynolds number is increased. At $\\mathit{Re}= 12\\hspace{0.167em} 000$ , the orbital diameter reaches approximately one sphere diameter. Of interest, this transition sequence is distinct from that for a vertically tethered heavy sphere, which undergoes transition to quasi-circular orbits beyond $\\mathit{Re}= 500$ .

A study of the geometry and parameter dependence of vortex breakdown

Publisher: AIP Publishing

Date: 04-2015

DOI: 10.1063/1.4916352

Abstract: The types of vortex breakdown observed in the torsionally driven cylinder (TDC) flow and in the flow through an open-ended pipe are compared. The connection between the various breakdown types is specifically addressed, and the differences in manifestation of breakdown are attributed to the different Reynolds number regimes involved. Here, in both cases, the Reynolds number is based on quantities associated with the vortex core immediately upstream of breakdown, rather than the more geometry-specific Reynolds number defined in the previous work. Thus, the relationship between the TDC flow and the flows observed in other, more open geometries, is clarified. The predominantly asymmetric breakdown observed in open high Reynolds number flows is replaced by a closed bubble form with decreasing Reynolds number in the TDC. Three-dimensional numerical simulations support this interpretation, showing that the 3D spiral type of breakdown is replaced by a TDC-type axisymmetric breakdown in an open pipe as the Reynolds number is reduced. The stability of the three-dimensional solutions indicates that spiral breakdown modes stabilise at lower Reynolds number, leading to an axisymmetric breakdown state as a stable evolved flow solution.

Sources of acoustic resonance generated by flow around a long rectangular plate in a duct

Publisher: Elsevier BV

Date: 12-2003

DOI: 10.1016/J.JFLUIDSTRUCTS.2003.08.016

The effect of changed mass ratio on the motion of a tethered cylinder

Publisher: Springer Netherlands

Date: 2004

DOI: 10.1007/978-94-007-0995-9_8

Engineering imaging: Using particle image velocimetry to see physiology in a new light

Publisher: Wiley

Date: 02-2009

DOI: 10.1111/J.1440-1681.2008.05102.X

Abstract: 1. Despite the array of sophisticated imaging techniques available for biological applications, none of the standard biomedical techniques adequately provides the capability to measure motion and flow. Those techniques currently in use are particularly lacking in spatial and temporal resolution. 2. Herein, we introduce the technique of particle image velocimetry. This technique is a well-established tool in engineering research and industry. Particle image velocimetry is continuing to develop and has an increasing number of variants. 3. Three case studies are presented: (i) the use of microparticle image velocimetry to study flow generated by high-frequency oscillatory ventilation in a human airway model (ii) the use of stereoparticle image velocimetry to study stirred cell and tissue culture devices and (iii) a three-dimensional X-ray particle image velocimetry technique used to measure flow in an in vitro vascular flow model. 4. The case studies highlight the vast potential of applying the engineering technique of particle image velocimetry and its many variants to current research problems in physiology.

From the circular cylinder to the flat plate wake: The variation of Strouhal number with Reynolds number for elliptical cylinders

Publisher: AIP Publishing

Date: 10-2013

DOI: 10.1063/1.4827521

Abstract: The variation of Strouhal number with Reynolds number is quantified experimentally for a series of elliptical cylinders spanning aspect ratios between \\documentclass[12pt]{minimal}\\begin{document}$\\mbox{\\textit {Ar}}=1$\\end{document}Ar=1, corresponding to a circular cylinder, and \\documentclass[12pt]{minimal}\\begin{document}$\\mbox{\\textit {Ar}}=0$\\end{document}Ar=0, corresponding to a flat plate, over the Reynolds number range \\documentclass[12pt]{minimal}\\begin{document}$100 \\leqslant \\mbox{\\textit {Re}}\\leqslant 300$\\end{document}100⩽Re⩽300. The widths of the spectral peaks in Fourier space at each Reynolds number, together with changes in the shape or continuity of the Strouhal number curves, provide information of underlying three-dimensional transitions. Whilst modified versions of the mode A and B transitions of a circular cylinder wake occur at aspect ratios above \\documentclass[12pt]{minimal}\\begin{document}$\\mbox{\\textit {Ar}}\\approx 0.4$\\end{document}Ar≈0.4, one major difference is observed for \\documentclass[12pt]{minimal}\\begin{document}$\\mbox{\\textit {Ar}}\\lesssim 0.4$\\end{document}Ar≲0.4. In a limited range of Reynolds numbers, the wake appears to re-laminarize after it has already undergone three-dimensional transition. This flow regime is characterized by a strictly periodic vortex shedding.

Body-caudal fin fish-inspired self-propulsion study on burst-and-coast and continuous swimming of a hydrofoil model

Publisher: AIP Publishing

Date: 09-2021

DOI: 10.1063/5.0061417

Abstract: The present study examines the energy efficiency of self-propelled hydrofoils for various modes and kinematics of swimming adopted by various body-caudal fin fish. In particular, this work considers the intermittent burst-and-coast (B& C) and continuous swimming modes, and examines the effect of the undulating and/or pitching swimming kinematics, adopted by the undulating body of anguilliform fish and pitching caudal fin of carangiform and thunniform fish. Notably, B& C swimming is adopted in nature mostly by the latter class but rarely by the former. This fact forms the basis of our study on the hydrodynamics and propulsion performance for both classes of fish-inspired swimming using a NACA0012 hydrofoil model. This analysis explores a large parameter space covering undulation wavelength, 0.8≤λ*& ∞, Reynolds number, 50≤Ref≤1500, and duty cycle (DC), 0.1≤DC≤1, with the DC representing the fraction of time in B& C swimming. The fluid–structure dynamics-based vortex-shedding-process is investigated, where B& C swimming results in either an asymmetric reverse von Karman (RVK) or forward von Karman vortex street, rather than a symmetric RVK vortex street observed during continuous swimming. It is demonstrated that the B& C swimming results in an energy saving, although there is a concomitant increase in the travel time. Moreover, our results show that B& C swimming is effective for carangiform and thunniform tail-like kinematics but not for anguilliform body-like kinematics of the hydrofoil. Thus, the predictions are consistent with the observed swimming behavior adopted by a fish in nature and provide input into the efficient design of unmanned underwater vehicles.

Application of Particle Image Velocimetry and Reference Image Topography to jet shock cells using the hydraulic analogy

Publisher: Springer Science and Business Media LLC

Date: 24-03-2011

DOI: 10.1007/S00348-011-1072-8

Wake behaviour and instability of flow through a partially blocked channel

Publisher: Cambridge University Press (CUP)

Date: 14-06-2007

DOI: 10.1017/S0022112007005861

Abstract: The two-dimensional flow through a constricted channel is studied. A semi-circular bump is located on one side of the channel and the extent of blockage is varied by adjusting the radius of the bump. The blockage is varied between 0.05 and 0.9 of the channel width and the upstream Reynolds number between 25 and 3000. The geometry presents a simplified blockage specified by a single parameter, serving as a starting point for investigations of other more complex blockage geometries. For blockage ratios in excess of 0.4, the variation of reattachment length with Reynolds number collapses to within approximately 15%, while at lower ratios the behaviour differs. For the constrained two-dimensional flow, various phenomena are identified, such as multiple mini-recirculations contained within the main recirculation bubble and vortex shedding at higher Reynolds numbers. The stability of the flow to three-dimensional perturbations is analysed, revealing a transition to a three-dimensional state at a critical Reynolds number which decreases with higher blockage ratios. Separation lengths and the onset and structure of three-dimensional instability observed from the geometry of blockage ratio 0.5 resemble results taken from backward-facing step investigations. The question of the underlying mechanism behind the instability being either centrifugal or elliptic in nature and operating within the initial recirculation zone is analytically tested.

A bioreactor model of mouse tumor progression

Publisher: Hindawi Limited

Date: 2007

DOI: 10.1155/2007/32754

Abstract: The present study represents an investigation of a novel stirred bioreactor for culture of a transformed cell line under defined hydrodynamic conditions in vitro. Cell colonies of the EL-4 mouse lymphoma cell line grown for the first time in a rotating disc bioreactor (RDB), were observed to undergo changes in phenotype in comparison to standard, static flask cultures. RDB cultures, with or without agitation, promoted the formation of adherent EL-4 cell plaques that merged to form contiguous tumor-like masses in longer-term cultures, unlike the unattached spheroid aggregates of flask cultures. Plaques grown under agitated conditions were further altered in morphology and distribution in direct response to fluid mechanical stimuli. Plaque colonies growth in RDBs with or without agitation also exhibited significant increases in production of interleukin-4 (IL-4) and lactate, suggesting an inducible “Warburg effect.” Increases in cell biomass in RDB cultures were no different to flask cultures, though a trend toward a marginal increase was observed at specific rotational speeds. The RDB may therefore be a suitable alternative method to study mechanisms of tumor progression and invasiveness in vitro, under more complex physicochemical conditions that may approximate natural tissue environments.

Numerical simulation of heat transfer in the separated and reattached flow on a blunt flat plate

Publisher: Elsevier BV

Date: 11-1986

DOI: 10.1016/0735-1933(86)90045-X

Evolutionary shape optimisation enhances the lift coefficient of rotating wing geometries

Publisher: Cambridge University Press (CUP)

Date: 11-04-2019

DOI: 10.1017/JFM.2019.183

Abstract: Wing shape is an important factor affecting the aerodynamic performance of wings of monocopters and flapping-wing micro air vehicles. Here, an evolutionary structural optimisation method is adapted to optimise wing shape to enhance the lift force due to aerodynamic pressure on the wing surfaces. The pressure distribution is observed to vary with the span-based Reynolds number over a range covering most insects and samaras. Accordingly, the optimised wing shapes derived using this evolutionary approach are shown to adjust with Reynolds number. Moreover, these optimised shapes exhibit significantly higher lift coefficients ( ${\\sim}50\\,\\%$ ) than the initial rectangular wing forebear. Interestingly, the optimised shapes are found to have a large area outboard, broadly in line with the features of high-lift forewings of multi-winged insects. According to specific aerodynamic performance requirements, this novel method could be employed in the optimisation of improved wing shapes for micro air vehicles.

The shear-layer instability of a circular cylinder wake

Publisher: AIP Publishing

Date: 10-01-2005

DOI: 10.1063/1.1852581

Abstract: A reinterpretation is made of previously published data concerning the frequency of the instability waves in the separated shear layer from a circular cylinder for Reynolds numbers in the range 103–105. An accurate fit to the observed variation can be achieved using a piecewise fit based on theoretical and empirical arguments. A logical conclusion is that the ratio of the frequency of the instability waves to the Kármán vortex shedding frequency is indeed determined by the boundary-layer properties at separation, as suggested by Bloor.

Acoustic sources in a tripped flow past a resonator tube

Publisher: American Institute of Aeronautics and Astronautics (AIAA)

Date: 06-1992

DOI: 10.2514/3.11091

Transition to chaos in the wake of a rolling sphere

Publisher: Cambridge University Press (CUP)

Date: 22-02-2012

DOI: 10.1017/JFM.2012.4

Abstract: The wake of a sphere rolling along a wall at low Reynolds number is investigated numerically and experimentally. Two successive transitions are identified in this flow, as the Reynolds number is increased. The first leads to the periodic shedding of planar symmetric hairpin vortices. The second and previously unknown transition involves a loss of planar symmetry and a low-frequency lateral oscillation of the wake, exhibiting a surprising 7:3 resonance with the hairpin vortex shedding. The two transitions are characterized by dye visualizations and quantitative information obtained from numerical simulations, such as force coefficients and wake frequencies (Strouhal numbers). Both transitions are found to be supercritical. Further increasing the Reynolds number, the flow becomes progressively more disorganized and chaotic. Overall, the transition sequence for the rolling sphere is closer to the one for a non-rotating sphere in a free stream than to that of a non-rotating sphere close to a wall.

X-ray velocimetry and haemodynamic forces within a stenosed femoral model at physiological flow rates

Publisher: Springer Science and Business Media LLC

Date: 04-02-2011

DOI: 10.1007/S10439-011-0260-2

Abstract: High resolution in vivo velocity measurements within the cardiovascular system are essential for accurate calculation of vessel wall shear stress, a highly influential factor for the progression of arterial disease. Unfortunately, currently available techniques for in vivo imaging are unable to provide the temporal resolution required for velocity measurement at physiological flow rates. Advances in technology and improvements in imaging systems are allowing a relatively new technique, X-ray velocimetry, to become a viable tool for such measurements. This study investigates the haemodynamics of pulsatile blood flow in an optically opaque in vitro model at physiological flow rates using X-ray velocimetry. The in vitro model, an asymmetric stenosis, is designed as a 3:1 femoral artery with the diameter and flow rate replicating vasculature of a mouse. Velocity measurements are obtained over multiple cycles of the periodic flow at high temporal and spatial resolution (1 ms and 29 μm, respectively) allowing accurate measurement of the velocity gradients and calculation of the wall shear stress. This study clearly illustrates the capability of in vitro X-ray velocimetry, suggesting it as a possible measurement technique for future in vivo vascular wall shear stress measurement.

Hydraulic analogy study of supersonic rectangular-jet screech control with cylinders

Publisher: American Institute of Aeronautics and Astronautics (AIAA)

Date: 07-2007

DOI: 10.2514/1.26714

Mixing in a vortex breakdown flow

Publisher: Cambridge University Press (CUP)

Date: 14-08-2013

DOI: 10.1017/JFM.2013.226

Abstract: In this paper we present experimental and theoretical results on the mixing inside a cylinder with a rotating lid. The helical flow that is created by the rotation of the disc is well known to exhibit a vortex breakdown bubble over a finite range of Reynolds numbers. The mixing properties of the flow are analysed quantitatively by measuring the exponential decay of the variance as a function of time. This homogenization time is extremely sensitive to the asymmetries of the flow, which are introduced by tilting the rotating or the stationary disc and accurately measured using particle image velocimetry (PIV). In the absence of vortex breakdown, the homogenization time is strongly decreased (by a factor of 10) with only a moderate tilt angle of the rotating lid (of the order of $1{5}^{\\circ } $ ). This phenomenon can be explained by the presence of small radial jets at the periphery which create a strong convective mixing. A simple model of exchange flow between the periphery and the bulk correctly predicts the scaling laws for the homogenization time. In the presence of vortex breakdown, the scalar is trapped inside the vortex breakdown bubble, and thus increases substantially the time needed for homogenization. Curiously, the tilt of the rotating lid has a weak effect on the mixing, but a small tilt of the stationary disc (of the order of ${2}^{\\circ } $ ) strongly decreases (by a factor of 10) the homogenization time. Even more surprising is that the homogenization time erges when the size of the bubble vanishes. All of these features are recovered by applying the Melnikov theory to calculate the volume of the lobes that exit the bubble. It is the first time that this technique has been applied to a three-dimensional stationary flow with a non-axisymmetric perturbation and compared with experimental results, although it has been applied often to two-dimensional flows with a periodic perturbation.

Effect of small asymmetries on axisymmetric stenotic flow

Publisher: Cambridge University Press (CUP)

Date: 19-03-2013

DOI: 10.1017/JFM.2013.109

Abstract: Flow through axisymmetric and eccentric sinuous stenoses is investigated numerically, for Reynolds numbers up to 400. The eccentricity consists of an offset of the stenosis throat. A range of stenosis eccentricity is tested the wake flow is found to be highly sensitive to small eccentricities in the stenosis geometry, even with stenosis offsets of the order of the machining precision of experimental test-sections. Comparisons are made between the numerically simulated flow through stenoses with small eccentricities and results from the literature of non-axisymmetric flows through nominally axisymmetric geometries. The effect of distortion to the inlet Poiseuille velocity profile is also investigated and found to have a significantly less severe effect on the downstream wake flow than geometric eccentricity.

Confined flow vortex breakdown control using a small rotating disk

Publisher: AIP Publishing

Date: 11-11-2004

DOI: 10.1063/1.1813061

Abstract: As part of a program to investigate the effectiveness of vortex breakdown in bioreactors for cell and tissue growth, a nonintrusive method of flow control is presented. A small rotating disk flush-mounted opposite to the rotating lid in a confined cylindrical vessel is found to precipitate or delay the onset of vortex breakdown depending on whether it is corotating or counterrotating, respectively. Furthermore, corotation increases the bubble radial and axial dimensions while shifting the bubble in the upstream direction. By contrast, counterrotation tends to reduce the size of the bubble, or completely suppress it, while shifting the bubble in the downstream direction. It has also been shown that corotating swirl addition using the small disk is orders of magnitude more energy efficient in manipulating the vortex breakdown bubble than using end wall rotation.

Surface-functionalization of PDMS for potential micro-bioreactor and embryonic stem cell culture applications

Publisher: Royal Society of Chemistry (RSC)

Date: 2013

DOI: 10.1039/C2TB00019A

Three-dimensionality in the wake of a rotating cylinder in a uniform flow

Publisher: Cambridge University Press (CUP)

Date: 02-2013

DOI: 10.1017/JFM.2012.542

Abstract: The wake of a rotating circular cylinder in a free stream is investigated for Reynolds numbers $\\mathit{Re}\\leqslant 400$ and non-dimensional rotation rates of $\\alpha \\leqslant 2. 5$ . Two aspects are considered. The first is the transition from a steady flow to unsteady flow characterized by periodic vortex shedding. The two-dimensional computations show that the onset of unsteady flow is delayed to higher Reynolds numbers as the rotation rate is increased, and vortex shedding is suppressed for $\\alpha \\geqslant 2. 1$ for all Reynolds numbers in the parameter space investigated. The second aspect investigated is the transition from two-dimensional to three-dimensional flow using linear stability analysis. It is shown that at low rotation rates of $\\alpha \\leqslant 1$ , the three-dimensional transition scenario is similar to that of the non-rotating cylinder. However, at higher rotation rates, the three-dimensional scenario becomes increasingly complex, with three new modes identified that bifurcate from the unsteady flow, and two modes that bifurcate from the steady flow. Curves of marginal stability for all of the modes are presented in a parameter space map, the defining characteristics for each mode presented, and the physical mechanisms of instability are discussed.

Anguilliform and carangiform fish-inspired hydrodynamic study for an undulating hydrofoil: Effect of shape and adaptive kinematics

Publisher: American Physical Society (APS)

Date: 14-09-2022

DOI: 10.1103/PHYSREVFLUIDS.7.094102

Wake formation behind a rolling sphere

Publisher: AIP Publishing

Date: 07-2008

DOI: 10.1063/1.2949312

Abstract: Experimental flow visualizations are presented depicting the flow behind a spherical body moving on a plane wall. In the Reynolds number range of 100& Re& , four distinct wake modes occur which are dependent on the imposed rotation rate of the body. Five different rotation rates are examined: two with forward rolling, one with pure translation (zero rotation), and two with reversed rolling. As the sphere undergoes forward rolling, steady and unsteady wake modes are observed which bear similarities to the flow behind an isolated sphere in a free stream. However, for cases with reversed and zero rotation of the sphere, a new antisymmetric wake mode is discovered.

Augmented forced convection heat transfer in separated flow around a blunt flat plate

Publisher: Elsevier BV

Date: 03-1991

DOI: 10.1016/0894-1777(91)90062-V

Volatile and Color Composition of Young and Model-Aged Shiraz Wines As Affected by Diammonium Phosphate Supplementation Before Alcoholic Fermentation

Publisher: American Chemical Society (ACS)

Date: 13-09-2008

DOI: 10.1021/JF801273K

Abstract: A Shiraz must with low yeast assimilable nitrogen (YAN) was supplemented with two concentrations of diammonium phosphate (DAP) and then fermented with maceration on grape skins. The nonvolatile, volatile, and color composition of the final wines were investigated. Ethanol and residual sugars were not affected by DAP supplementation, while glycerol, SO 2, and residual YAN increased and acetic acid decreased. DAP-supplemented treatments gave rise to higher concentrations of acetates, fatty acids, and fatty acid ethyl esters but lower concentrations of branched-chain fatty acids and their ethyl esters. No major difference between treatments was observed for higher alcohols, monoterpenes, norisoprenoids, and low-molecular-weight sulfur compounds. DAP-supplemented fermentations resulted in wines with higher concentrations of malvidin-3-glucoside, higher color intensity, and altered color tonality. Model aging studies indicated that higher concentrations of esters are still present in wines from the DAP-treated fermentations after aging. DAP supplementation also resulted in increased concentrations of dimethyl sulfide after model aging. It can be concluded that DAP treatment of a low YAN must fermented by maceration on skins can significantly affect wine color, aroma, and flavor.

Decomposition of fluid forcing and phase synchronisation for in-line vortex-induced vibration of a circular cylinder

Publisher: Cambridge University Press (CUP)

Date: 12-05-2022

DOI: 10.1017/JFM.2022.359

Abstract: We present a decomposition of the streamwise fluid force for in-line vortex-induced vibration (VIV) to provide insight into how the wake drag acts as a driving force in fluid–structure interaction. This force decomposition is an extension of that proposed in the recent work of Konstantinidis et al. ( J. Fluid Mech. , vol. 907, 2021, p. A34), and is applied to and validated by our experiments examining a circular cylinder freely vibrating in line with the free stream. It is revealed from the decomposition and linear analysis that two regimes of significant vibration are in phase synchronisation, while they are separated by a desynchronised regime marked by competition between non-stationary frequency responses of the cylinder vibration and the vortex shedding. Of interest, such a near-resonance desynchronisation regime is not seen in the transverse vibration case.

Wake of forced flow around elliptical leading edge plates

Publisher: Elsevier BV

Date: 02-2005

DOI: 10.1016/J.JFLUIDSTRUCTS.2004.10.007

Dynamics and stability of the wake behind tandem cylinders sliding along a wall

Publisher: Cambridge University Press (CUP)

Date: 28-03-2013

DOI: 10.1017/JFM.2013.93

Abstract: The dynamics and stability of the flow past two cylinders sliding along a wall in a tandem configuration is studied numerically for Reynolds numbers ( $\\mathit{Re}$ ) between 20 and 200, and streamwise separation distances between 0.1 and 10 cylinder diameters. For cylinders at close separations, the onset of unsteady two-dimensional flow is delayed to higher $\\mathit{Re}$ compared with the case of a single sliding cylinder, while at larger separations, this transition occurs earlier. For Reynolds numbers above the threshold, shedding from both cylinders is periodic and locked. At intermediate separation distances, the wake frequency shifts to the subharmonic of the leading-cylinder shedding frequency, which appears to be due to a feedback cycle, whereby shed leading-cylinder vortices interact strongly with the downstream cylinder to influence subsequent leading-cylinder shedding two cycles later. In addition to the shedding frequency, the drag coefficients for the two cylinders are determined for both the steady and unsteady regimes. The three-dimensional stability of the flow is also investigated. It is found that, when increasing the Reynolds number at intermediate separations, an initial three-dimensional instability develops, which disappears at higher $\\mathit{Re}$ . The new two-dimensional steady flow again becomes unstable, but with a different three-dimensional instability mode. At very close spacings, when the two cylinders are effectively seen by the flow as a single body, and at very large spacings, when the cylinders form independent wakes, the flow characteristics are similar to those of a single cylinder sliding along a wall.

Asymmetric structure and non-linear transition behaviour of the wakes of toroidal bodies

Publisher: Elsevier BV

Date: 2004

DOI: 10.1016/J.EUROMECHFLU.2003.04.005

Control of confined vortex breakdown with partial rotating lids

Publisher: Cambridge University Press (CUP)

Date: 29-11-2013

DOI: 10.1017/JFM.2013.596

Abstract: Experiments were conducted to determine the effectiveness of controlling vortex breakdown in a confined cylindrical vessel using a small rotating disk, which was flush-mounted into the opposite endwall to the rotating endwall driving the primary recirculating flow. The results show that the control disk, with relatively little power input, can modify the azimuthal and axial flow significantly, changing the entire flow structure in the cylinder. Co-rotation was found to precipitate vortex breakdown onset whereas counter-rotation delays it. Furthermore, for the Reynolds-number range over which breakdown normally exists, co-rotation increases the bubble radial and axial dimensions, while shifting the bubble in the upstream direction. By contrast, counter-rotation tends to reduce the size of the bubble, or completely suppress it, while shifting the bubble in the downstream direction. These effects are lified substantially by the use of larger control disks and higher rotation ratios. A series of numerical simulations close to the onset Reynolds number reveals that the control disk acts to generate a rotation-rate-invariant local positive or negative azimuthal vorticity source away from the immediate vicinity of the control disk but upstream of breakdown. Advection of this source along streamlines modifies the strength of the azimuthal vorticity ring, which effectively controls whether the flow reverses on the axis, and thus, in turn, whether vortex breakdown occurs. The vorticity source generated by the control disk scales approximately linearly with rotation ratio and cubically with disk diameter this allows the observed variation of the critical Reynolds number to be approximately predicted.

Prediction of flutter of turbine blades in a Transonic Annular Cascade

Publisher: ASME International

Date: 29-05-2005

DOI: 10.1115/1.2060731

Abstract: A parallel multiblock Navier-Stokes solver with the k‐ω turbulence model is used to solve the unsteady flow through an annular turbine cascade, the transonic Standard Test Case 4, Test 628. Computations are performed on a two- and three-dimensional model of the blade row with either the Euler or the Navier-Stokes flow models. Results are compared to the experimental measurements. Comparisons of the unsteady surface pressure and the aerodynamic d ing are made between the three-dimensional, two-dimensional, inviscid, viscous simulations, and experimental data. Differences are found between the stability predictions by the two- and three-dimensional computations, and the Euler and Navier-Stokes computations due to three-dimensionality of the cascade model and the presence of a boundary layer separation, respectively.

Experimental investigation of in-line flow-induced vibration of a rotating circular cylinder

Publisher: Cambridge University Press (CUP)

Date: 25-05-2018

DOI: 10.1017/JFM.2018.357

Abstract: This study experimentally investigates the in-line flow-induced vibration (FIV) of an elastically mounted circular cylinder under forced axial rotation in a free stream. The present experiments characterise the structural vibration, fluid forces and wake structure of the fluid–structure system at a low mass ratio (the ratio of the total mass to the displaced fluid mass) over a wide parameter space spanning the reduced velocity range $5\leqslant U^{\ast }\leqslant 32$ and the rotation rate range $0\leqslant \unicode[STIX]{x1D6FC}\leqslant 3.5$ , where $U^{\ast }=U/(\,f_{nw}D)$ and $\unicode[STIX]{x1D6FC}=|\unicode[STIX]{x1D6FA}|D/(2U)$ , with $U$ the free-stream velocity, $D$ the cylinder outer diameter, $f_{nw}$ the natural frequency of the system in quiescent water and $|\unicode[STIX]{x1D6FA}|$ the angular velocity of the cylinder rotation. The corresponding Reynolds number (defined by $Re=UD/\unicode[STIX]{x1D708}$ , with $\unicode[STIX]{x1D708}$ the kinematic viscosity of the fluid) was varied over the interval $1349\leqslant Re\leqslant 8624$ , where it is expected that the FIV response is likely to be relatively insensitive to the Reynolds number. The fluid–structure system was modelled using a low-friction air-bearing system in conjunction with a free-surface water-channel facility. Three vibration regions that exhibited vortex-induced vibration (VIV) synchronisation, rotation-induced galloping and desynchronised responses were observed. In both the VIV synchronisation and rotation-induced galloping regions, significant cylinder vibration was found to be correlated with wake–body synchronisation within the rotation rate range $2.20\lesssim \unicode[STIX]{x1D6FC}\lesssim 3.15$ . Of significant interest, the frequency of the streamwise fluid force could be modulated by the imposed rotation to match that of the transverse lift force, resulting in harmonic synchronisation. Measurements using the particle image velocimetry (PIV) technique were performed to identify the wake structure. Interestingly, the imposed rotation can cause regular vortex shedding in in-line FIV at rotation rates that see suppression of the Bénard–von-Kármán vortex shedding in the case of a rigidly mounted cylinder ( $\unicode[STIX]{x1D6FC}\gtrsim 1.75$ ). There is a monotonic increase in the drag coefficient with rotation rate beyond $\unicode[STIX]{x1D6FC}=2$ for a non-oscillating rotating cylinder. This suggests that the mechanism for sustaining the large rotation-induced galloping oscillations at higher $\unicode[STIX]{x1D6FC}$ is due to a combination of aerodynamic forcing from the locked induced vortex shedding associated with the oscillations, assisted by aerodynamic forcing, evaluated using quasi-steady theory.

Hydrodynamics of a fish-like body undulation mechanism: Scaling laws and regimes for vortex wake modes

Publisher: AIP Publishing

Date: 10-2021

DOI: 10.1063/5.0062304

Abstract: A comprehensive two-dimensional numerical investigation has been undertaken to calculate the energetic cost of propulsion and the various flow transitions of a fish-like body undulation mechanism based on a National Advisory Committee for Aeronautics 0012 hydrofoil. This covers a wide range of Strouhal (0≤St≤1.4) and Reynolds (500≤Re≤5000) numbers from simulations based on a level-set function immersed-interface method. It is found that the time-averaged thrust coefficient displays a quadratic relationship with increasing St, and increases significantly with Re. Additionally, the time-averaged input power coefficient exhibits a cubic dependence with increasing St but is independent of Re. Both St dependences agree with those previously observed experimentally and numerically for an oscillating foil however, for similar ranges of governing parameters, comparisons suggest that the body undulation mechanism possesses a higher propulsive efficiency. The St∝Re−0.19 scaling for the drag-to-thrust transition is consistent with that found for a wide variety of fish and birds in nature. Interestingly, for cases with an undulation wave-speed below the free-stream speed, the time-averaged drag coefficient is found to be higher than that of a stationary hydrofoil at the same Re. Furthermore, the time-averaged input power coefficient is negative, indicating the potential for the undulation mechanism to extract energy from the free-stream. Eight different wake patterns/transitions are documented for the parameter space these have been assembled into a wake-regime parameter-space map. The present findings should aid in predicting and understanding different hydrodynamic forces and wake patterns for undulating kinematics.

Simulation of the control of vortex breakdown in a closed cylinder using a small rotating disk

Publisher: AIP Publishing

Date: 02-2009

DOI: 10.1063/1.3073747

Abstract: The enhancement or suppression of vortex breakdown in a closed cylinder caused by a small rotating disk embedded in the nonrotating endwall is simulated in this study. This paper shows that corotation or counter-rotation of the control disk with respect to the driving lid is able to promote or suppress the “bubble-type” vortex breakdown. This is achieved using only a small fraction of the power required to drive the main lid. The simulations show that the vortex breakdown induced or suppressed by flow control displays similar characteristics near the breakdown region as produced by varying the flow Reynolds number. These include near-axis swirl, centerline axial velocity, and centerline pressure. The influence of the size of the control disk is also quantified.

Bioreducible PEI-functionalized glycol chitosan: A novel gene vector with reduced cytotoxicity and improved transfection efficiency

Publisher: Elsevier BV

Date: 11-2016

DOI: 10.1016/J.CARBPOL.2016.07.080

Abstract: Non-viral gene delivery has been well recognised as a potential way to address the main safety limitations of viral gene carriers. A new redox-responsive PEI derivative was designed, synthesized and evaluated for non-viral delivery applications of GFP DNA. Glycol chitosan was covalently attached to highly branched LMW PEI via bio-cleavable disulfide bonds to synthesize a new redox-responsive gene carrier (GCS-ss-PEI). Results showed the enhanced buffering capacity of GCS-ss-PEI, 43.1%, compared to the buffering capacities of both LMW PEI and HMW PEI, 23.2% and 31.5%, respectively, indicating more likely endosomal escape of the entrapped gene for GCS-ss-PEI. Moreover, electrophoretic gel retardation assay, performed to investigate the binding strength of GCS-ss-PEI to GFP DNA, showed stronger complexation with GFP DNA in GCS-ss-PEI at non-GSH condition. Employing GCS and incorporation of disulfide bonds in the structure of the PEI-based gene carrier resulted in improved redox-responsivity, reduced toxicity, enhanced endosomal escape and GFP DNA transfection. The facilitated intracellular gene release along with excellent redox-responsive characteristics and dropped cytotoxicity suggests the potential of GCS-ss-PEI as a candidate for developing highly efficient and safe gene vectors.

The flow past a circular cylinder translating at different heights above a wall

Publisher: Elsevier BV

Date: 08-2013

DOI: 10.1016/J.JFLUIDSTRUCTS.2012.08.007

Vortex shedding and three-dimensional behaviour of flow past a cylinder confined in a channel

Publisher: Elsevier BV

Date: 07-2011

DOI: 10.1016/J.JFLUIDSTRUCTS.2011.02.007

Response of base suction and vortex shedding from rectangular prisms to transverse forcing

Publisher: Cambridge University Press (CUP)

Date: 25-06-2002

DOI: 10.1017/S0022112002008534

Abstract: In previous experiments, the vortex-shedding frequency in the flow around rectangular prisms has been found to follow a stepwise variation with chord-to-thickness ratio for two different situations: the natural shedding at low Reynolds number and the excitation of a resonant transverse acoustic mode of a duct for flows at moderate Reynolds numbers. This stepwise variation disappears for natural shedding at Reynolds number higher than approximately 2000 however, it is present at the higher Reynolds numbers for the acoustically perturbed case. The present experimental study shows that if the flow is forced by small transverse oscillations, similar in form to the resonant transverse acoustic mode, the leading-edge and trailing-edge vortex shedding are locked over a wide range of forcing frequencies. However, a stepwise variation in the frequency at which peak base drag occurs is found even at these higher Reynolds numbers. The stepwise frequency variation of vortex shedding in the natural shedding case and the acoustic resonance case are then explained in terms of preference of the flow to shed trailing-edge vortices at peak base drag.

Vortex-induced vibration of elastically-mounted spheres: A comparison of the response of three degrees of freedom and one degree of freedom systems

Publisher: Elsevier BV

Date: 08-2019

DOI: 10.1016/J.JFLUIDSTRUCTS.2019.02.005

A fluid dynamics approach to bioreactor design for cell and tissue culture

Publisher: Wiley

Date: 2006

DOI: 10.1002/BIT.20960

Abstract: The problem of controlling cylindrical tank bioreactor conditions for cell and tissue culture purposes has been considered from a flow dynamics perspective. Simple laminar flows in the vortex breakdown region are proposed as being a suitable alternative to turbulent spinner flask flows and horizontally oriented rotational flows. Vortex breakdown flows have been measured using three-dimensional Stereoscopic particle image velocimetry, and non-dimensionalized velocity and stress distributions are presented. Regions of locally high principal stress occur in the vicinity of the impeller and the lower sidewall. Topological changes in the vortex breakdown region caused by an increase in Reynolds number are reflected in a redistribution of the peak stress regions. The inclusion of submerged scaffold models adds complexity to the flow, although vortex breakdown may still occur. Relatively large stresses occur along the edge of disks jutting into the boundary of the vortex breakdown region.

Wake state and energy transitions of an oscillating cylinder at low Reynolds number

Publisher: AIP Publishing

Date: 06-2006

DOI: 10.1063/1.2204632

Abstract: This paper reports on an extensive parameter space study of two-dimensional simulations of a circular cylinder forced to oscillate transverse to the free-stream. In particular, the extent of the primary synchronization region, and the wake modes and energy transfer between the body and the fluid are analyzed in some detail. The frequency range of the primary synchronization region is observed to be dependent on Reynolds number, as are the wake modes obtained. Energy transfer is primarily dependent on frequency at low litudes of oscillation, but primarily dependent on litude at high litudes of oscillation. However, the oscillation litude corresponding to zero energy transfer is found to be relatively insensitive to Reynolds number. It is also found that there is no discernible change to the wake structure when the energy transfer changes from positive to negative.

Two- and three-dimensional wake transitions of an impulsively started uniformly rolling circular cylinder

Publisher: Cambridge University Press (CUP)

Date: 02-08-2017

DOI: 10.1017/JFM.2017.325

Abstract: This paper presents the characteristics of the different stages in the evolution of the wake of a circular cylinder rolling without slipping along a wall at constant speed, acquired through numerical stability analysis and two- and three-dimensional numerical simulations. Reynolds numbers between 30 and 300 are considered. Of importance in this study is the transition to three-dimensionality from the underlying two-dimensional periodic flow and, in particular, the way that the associated transitions influence the fluid forces exerted on the cylinder and the development and the structure of the wake. It is found that the steady two-dimensional flow becomes unstable to three-dimensional perturbations at $Re_{c,3D}=37$ , and that the transition to unsteady two-dimensional flow – or periodic vortex shedding – occurs at $Re_{c,2D}=88$ , thus validating and refining the results of Stewart et al. ( J. Fluid Mech. vol. 648, 2010, pp. 225–256). The main focus here is on Reynolds numbers beyond the transition to unsteady flow at $Re_{c,2D}=88$ . From impulsive start up, the wake almost immediately undergoes transition to a periodic two-dimensional wake state, which, in turn, is three-dimensionally unstable. Thus, the previous three-dimensional stability analysis based on the two-dimensional steady flow provides only an element of the full story. Floquet analysis based on the periodic two-dimensional flow was undertaken and new three-dimensional instability modes were revealed. The results suggest that an impulsively started cylinder rolling along a surface at constant velocity for $Re\\gtrsim 90$ will result in the rapid development of a periodic two-dimensional wake that will be maintained for a considerable time prior to the wake undergoing three-dimensional transition. Of interest, the mean lift and drag coefficients obtained from full three-dimensional simulations match predictions from two-dimensional simulations to within a few per cent.

Sphere–wall collisions: vortex dynamics and stability

Publisher: Cambridge University Press (CUP)

Date: 03-2007

DOI: 10.1017/S002211200600406X

Abstract: For moderate Reynolds numbers, a sphere colliding with a wall in the normal direction will lead to a trailing recirculating wake, threading over the sphere after impact and developing into a complex vortex-ring system as it interacts with vorticity generated at the wall. The primary vortex ring, consisting of the vorticity from the wake of the sphere prior to impact, persists and convects, relatively slowly, outwards away from the sphere owing to the motion induced from its image. The outward motion is arrested only a short distance from the axis because of the strong interaction with the secondary vorticity. In this paper, the structure and evolution of this combined vortex system, consisting of a strong compact primary vortex ring surrounded by and interacting with the secondary vorticity, is quantified through a combined experimental and numerical study. The Reynolds-number range investigated is (100 Re 2000). At Reynolds numbers higher than about 1000, a non-axisymmetric instability develops, leading to rapid distortion of the ring system. The growth of the instability does not continue indefinitely, because of the dissipative nature of the flow system it appears to reach a peak when the wake vorticity first forms a clean primary vortex ring. A comparison of the wavelength, growth rate and perturbation fields predicted from both linear stability theory and direct simulations, together with theoretical predictions, indicates that the dominant physical mechanism for the observed non-axisymmetric instability is centrifugal in nature. The maximum growth occurs at the edge of the primary vortex core, where the vorticity changes sign. Notably, this is a physical mechanism different from that proposed previously to explain the development of the three-dimensional flow of an isolated vortex ring striking a wall.

The effect of structural damping on flow-induced vibration of a thin elliptical cylinder

Publisher: Cambridge University Press (CUP)

Date: 23-10-0001

DOI: 10.1017/JFM.2023.776

Subharmonic mechanism of the mode C instability

Publisher: AIP Publishing

Date: 11-2005

DOI: 10.1063/1.2139682

Abstract: The perturbation field of the recently discovered subharmonic mode C instability in the wake behind a ring is compared via a side-by-side comparison to the perturbation fields of the modes A and B instabilities familiar from past studies of the vortex street behind a circular cylinder. Snapshots of the wake are presented over a full shedding cycle, along with evidence from a linear stability analysis, to verify and better understand how the subharmonic instability is sustained.

Variation in the critical mass ratio of a freely oscillating cylinder as a function of Reynolds number

Publisher: AIP Publishing

Date: 08-02-2005

DOI: 10.1063/1.1850871

Abstract: A two-dimensional numerical investigation of the flow-induced vibration of a circular cylinder held free to oscillate transverse to the free-stream direction has been performed. The simulations were performed over a Reynolds number range Re=[30,200] and for an infinite reduced velocity. Two regions of high litude oscillations are observed and are referred to as the viscous and higher Reynolds number range, respectively. The viscous range was observed for Re=[40,95] and the higher Reynolds number range was observed above Re=180. A critical mass ratio, below which appreciable litude oscillations are observed, is determined as a function of Reynolds number. For Reynolds numbers between the two ranges, only very small oscillations were observed for all mass ratios investigated.

Fluid-Structure Interaction of a Rolling Cylinder with Offset Centre-of-Mass

Publisher: Springer International Publishing

Date: 2016

DOI: 10.1007/978-3-319-27386-0_6

Orbital migration of protoplanets

Publisher: American Astronomical Society

Date: 12-1989

DOI: 10.1086/168138

Response of unconfined vortex breakdown to axial pulsing

Publisher: AIP Publishing

Date: 03-2006

DOI: 10.1063/1.2180290

Abstract: The response of unconfined swirling jets undergoing vortex breakdown to axial pulsing is explored experimentally. In particular, the combination of particle visualization and particle image velocimetry has enabled the effect of axial pulsing on the development of shear-layer flow structures and vortex breakdown to be quantified, as a function of both pulsing frequency and litude. A range of Reynolds and swirl numbers is considered. A key result is that application of low-level forcing at the natural frequency intensifies the shear-layer vortices considerably and results in a substantial relative downstream shift of the mean breakdown position.

Computed tomographic X-ray velocimetry for simultaneous 3D measurement of velocity and geometry in opaque vessels

Publisher: Springer Science and Business Media LLC

Date: 25-11-2012

DOI: 10.1007/S00348-010-1006-X

EXPERIMENTAL INVESTIGATION OF VORTEX SHEDDING FROM A PLATE - EFFECT OF EXTERNAL VELOCITY PERTURBATION

Publisher: Elsevier BV

Date: 12-1993

DOI: 10.1016/0167-6105(93)90034-L

Aerodynamic sources of acoustic resonance in a duct with baffles

Publisher: Elsevier BV

Date: 07-1990

DOI: 10.1016/0889-9746(90)90130-W

Surface topography of jet shock cells in a hydraulic analogy

Publisher: Springer Science and Business Media LLC

Date: 04-04-2010

DOI: 10.1007/S12650-010-0032-3

The feedback loop in impinging two-dimensional high-subsonic and supersonic jets

Publisher: Elsevier BV

Date: 02-1996

DOI: 10.1016/0894-1777(95)00084-4

Flow-induced vibration of a cube orientated at different incidence angles

Publisher: Elsevier BV

Date: 11-2019

DOI: 10.1016/J.JFLUIDSTRUCTS.2019.102701

An experimental investigation of flow-induced vibration of high-side-ratio rectangular cylinders

Publisher: Elsevier BV

Date: 11-2019

DOI: 10.1016/J.JFLUIDSTRUCTS.2019.01.021

Experiments on the elliptic instability in vortex pairs with axial core flow

Publisher: Cambridge University Press (CUP)

Date: 11-04-2011

DOI: 10.1017/JFM.2011.91

Abstract: Results are presented from an experimental study on the dynamics of pairs of vortices, in which the axial velocity within each core differs from that of the surrounding fluid. Co- and counter-rotating vortex pairs at moderate Reynolds numbers were generated in a water channel from the tips of two rectangular wings. Measurement of the three-dimensional velocity field was accomplished using stereoscopic particle image velocimetry, revealing significant axial velocity deficits in the cores. For counter-rotating pairs, the long-wavelength Crow instability, involving symmetric wavy displacements of the vortices, could be clearly observed using dye visualisation. Measurements of both the axial wavelength and the growth rate of the unstable perturbation field were found to be in good agreement with theoretical predictions based on the full experimentally measured velocity profile of the vortices, including the axial flow. The dye visualisations further revealed the existence of a short-wavelength core instability. Proper orthogonal decomposition of the time series of images from high-speed video recordings allowed a precise characterisation of the instability mode, which involves an interaction of waves with azimuthal wavenumbers m = 2 and m = 0. This combination of waves fulfils the resonance condition for the elliptic instability mechanism acting in strained vortical flows. A numerical three-dimensional stability analysis of the experimental vortex pair revealed the same unstable mode, and a comparison of the wavelength and growth rate with the values obtained experimentally from dye visualisations shows good agreement. Pairs of co-rotating vortices evolve in the form of a double helix in the water channel. For flow configurations that do not lead to merging of the two vortices over the length of the test section, the same type of short-wave perturbations were observed. As for the counter-rotating case, quantitative measurements of the wavelength and growth rate, and comparison with previous theoretical predictions, again identify the instability as due to the elliptic mechanism. Importantly, the spatial character of the short-wave instability for vortex pairs with axial flow is different from that previously found in pairs without axial flow, which exhibit an azimuthal variation with wavenumber m = 1.

Sound generated in laminar flow past a two-dimensional rectangular cylinder

Publisher: Elsevier BV

Date: 08-2006

DOI: 10.1016/J.JSV.2006.01.014

Pulsatile flow in stenotic geometries: flow behaviour and stability

Publisher: Cambridge University Press (CUP)

Date: 10-03-2009

DOI: 10.1017/S0022112008005338

Abstract: Pulsatile inlet flow through a circular tube with an axisymmetric blockage of varying size is studied both numerically and experimentally. The geometry consists of a long, straight tube and a blockage, semicircular in cross-section, serving as a simplified model of an arterial stenosis. The stenosis is characterized by a single parameter, the aim being to highlight fundamental behaviours of constricted pulsatile flows. The Reynolds number is varied between 50 and 700 and the stenosis degree by area between 0.20 and 0.90. Numerically, a spectral element code is used to obtain the axisymmetric base flow fields, while experimentally, results are obtained for a similar set of geometries, using water as the working fluid. For low Reynolds numbers, the flow is characterized by a vortex ring which forms directly downstream of the stenosis, for which the strength and downstream propagation velocity vary with the stenosis degree. Linear stability analysis is performed on the simulated axisymmetric base flows, revealing a range of absolute instability modes. Comparisons are drawn between the numerical linear stability analysis and the observed instability in the experimental flows. The observed flows are less stable than the numerical analysis predicts, with convective shear layer instability present in the experimental flows. Evidence is found of Kelvin–Helmholtz-type shear layer roll-ups nonetheless, the possibility of the numerically predicted absolute instability modes acting in the experimental flow is left open.

Experimental characterisation of fluid mechanics in a spinner flask bioreactor

Publisher: MDPI AG

Date: 17-10-2014

DOI: 10.3390/PR2040753

Effect of lactate and pH on mouse pluripotent stem cells: Importance of media analysis

Publisher: Elsevier BV

Date: 02-2017

DOI: 10.1016/J.BEJ.2016.11.005

A universal three-dimensional instability of the wakes of two-dimensional bluff bodies

Publisher: Cambridge University Press (CUP)

Date: 29-02-2016

DOI: 10.1017/JFM.2016.94

Abstract: Linear stability analysis of a wide range of two-dimensional and axisymmetric bluff-body wakes shows that the first three-dimensional mode to became unstable is always mode E. From the studies presented in this paper, it is speculated to be the universal primary 3D instability, irrespective of the flow configuration. However, since it is a transition from a steady two-dimensional flow, whether this mode can be observed in practice does depend on the nature of the flow set-up. For ex le, the mode E transition of a circular cylinder wake occurs at a Reynolds number of $\\mathit{Re}\\simeq 96$ , which is considerably higher than the steady to unsteady Hopf bifurcation at $\\mathit{Re}\\simeq 46$ leading to Bénard–von-Kármán shedding. On the other hand, if the absolute instability responsible for the latter transition is suppressed, by rotating the cylinder or moving it towards a wall, then mode E may become the first transition of the steady flow. A well-known ex le is flow over a backward-facing step, where this instability is the first global instability to be manifested on the otherwise two-dimensional steady flow. Many other ex les are considered in this paper. Exploring this further, a structural stability analysis (Pralits et al. J. Fluid Mech. , vol. 730, 2013, pp. 5–18) was conducted for the subset of flows past a rotating cylinder as the rotation rate was varied. For the non-rotating or slowly rotating case, this indicated that the growth rate of the instability mode was sensitive to forcing between the recirculation lobes, while for the rapidly rotating case, it confirmed sensitivity near the cylinder and towards the hyperbolic point. For the non-rotating case, the perturbation, adjoint and structural stability fields, together with the wavelength selection, show some similarities with those of a Crow instability of a counter-rotating vortex pair, at least within the recirculation zones. On the other hand, at much higher rotation rates, Pralits et al. ( J. Fluid Mech. , vol. 730, 2013, pp. 5–18) have suggested that hyperbolic instability may play a role. However, both instabilities lie on the same continuous solution branch in Reynolds number/rotation-rate parameter space. The results suggest that this particular flow transition at least, and probably others, may have a number of different physical mechanisms supporting their development.

Flow-induced vibrations of a tethered circular cylinder

Publisher: Elsevier BV

Date: 11-2004

DOI: 10.1016/J.JFLUIDSTRUCTS.2004.07.005

Flow around an impulsively arrested circular cylinder

Publisher: AIP Publishing

Date: 08-2007

DOI: 10.1063/1.2754346

Abstract: The vortex dynamics of the flow around a suddenly arrested translating circular cylinder is investigated by direct numerical simulation and water tank experiments. In the numerical study, a method of visualization of streaklines in simulated-particle tracking computations is proposed, which is based on a variable-variance two-dimensional Gaussian-weighted summation of particles in the vicinity of each interpolation point, and for which a close similarity with physical dye visualizations is found. This technique is used to identify the trajectory of both the wake vortices, as well as the secondary vortices induced as the original wake convects over the arrested cylinder. Observations show that, in a fashion similar to the flow past an arresting sphere, each wake vortex induces a counter-rotating vortex pair, which subsequently self-propels over a range of sometimes surprising trajectories as the Reynolds number and cylinder translation distance are varied. At low Reynolds numbers and short translation distances, the wake vortices propel past the cylinder, continuing in the direction of the original cylinder motion. At higher Reynolds numbers, the vortices deviate outwards in circular arcs of increasing curvature, even to the extent that the vortex pairs collide behind the cylinder. These trajectory curvatures are analyzed with respect to the circulation of the vortex pairs. At sufficiently long translation distances, a wake instability destroys the reflective symmetry about the wake centerline. This regime is investigated by both comparison with experiment and analysis of the discrepancy between the vorticity and particle fields at large post-arrest times.

Dual effect of F-actin targeted carrier combined with antimitotic drug on aggressive colorectal cancer cytoskeleton: Allying dissimilar cell cytoskeleton disrupting mechanisms

Publisher: Elsevier BV

Date: 11-2016

DOI: 10.1016/J.IJPHARM.2016.09.056

Abstract: A recent approach to colon cancer therapy is to employ selective drugs with specific extra/intracellular sites of action. Alteration of cytoskeletal protein reorganization and, subsequently, to cellular biomechanical behaviour during cancer progression highly affects the cancer cell progress. Hence, cytoskeleton targeted drugs are an important class of cancer therapy agents. We have studied viscoelastic alteration of the human colon adenocarcinoma cell line, SW48, after treatment with a drug delivery system comprising chitosan as the carrier and albendazole as the microtubule-targeting agent (MTA). For the first time, we have evaluated the biomechanical characteristics of the cell line, using the micropipette aspiration (MA) method after treatment with drug delivery systems. Surprisingly, employing a chitosan-albendazole pair, in comparison with both neat materials, resulted in more significant change in the viscoelastic parameters of cells, including the elastic constants (K

Vorticity generation and conservation on generalised interfaces in three-dimensional flows

Publisher: Cambridge University Press (CUP)

Date: 18-02-2022

DOI: 10.1017/JFM.2022.91

Abstract: This article presents a three-dimensional theory of vorticity creation on generalised interfaces, including both non-slip and free-slip boundaries, which generalises a previous two-dimensional formulation (Terrington et al. , J. Fluid Mech. , vol. 890, 2020, p. A5). Under this description, vorticity may be created on a boundary by the inviscid relative acceleration between fluid elements on each side of the boundary, driven by either tangential pressure gradients or body forces. Viscosity acts to transfer circulation between the vortex sheet representing the slip velocity on the interface, and the fluid interior, but is not responsible for the creation of vorticity on the interface. This formulation also describes a principle of vorticity conservation for interfacial and free-surface flows: in many flow configurations, the net generation of vorticity on the interface is zero, and the total circulation remains constant throughout flow evolution.

Power-Spectral density estimate of the Bloor-Gerrard instability in flows around circular cylinders

Publisher: Springer Science and Business Media LLC

Date: 15-08-2011

DOI: 10.1007/S00348-010-0955-4

Flow normal to a short cylinder with hemispherical ends

Publisher: AIP Publishing

Date: 04-2008

DOI: 10.1063/1.2899782

Abstract: The flow normal to a cylinder with hemispherical ends is computed using a spectral-element/Fourier method. With variation in the ratio of cylinder length to diameter, this body varies smoothly from a sphere to a straight circular cylinder, providing insight into the relationship between body topology and wake dynamics. This letter displays the wake structure for a range of cylinder lengths up to a Reynolds number of 300 and considers the wake alignment and symmetry at length ratios approaching a spherical body. A time-invariant wake consistent with that behind a sphere is found to preferentially align with a symmetry plane bisecting the major axis of short cylinders, whereas the periodic “hairpin” wake aligns with the minor axis thus the hairpin vortices shed from alternate sides of the cylinder, just as with Kármán vortex shedding from a circular cylinder. The plane of symmetry is found to break via a supercritical transition at a Reynolds number of 350±2.

Low-Reynolds-number wakes of elliptical cylinders: from the circular cylinder to the normal flat plate

Publisher: Cambridge University Press (CUP)

Date: 24-06-2014

DOI: 10.1017/JFM.2014.314

Abstract: While the wake of a circular cylinder and, to a lesser extent, the normal flat plate have been studied in considerable detail, the wakes of elliptic cylinders have not received similar attention. However, the wakes from the first two bodies have considerably different characteristics, in terms of three-dimensional transition modes, and near- and far-wake structure. This paper focuses on elliptic cylinders, which span these two disparate cases. The Strouhal number and drag coefficient variations with Reynolds number are documented for the two-dimensional shedding regime. There are considerable differences from the standard circular cylinder curve. The different three-dimensional transition modes are also examined using Floquet stability analysis based on computed two-dimensional periodic base flows. As the cylinder aspect ratio (major to minor axis) is decreased, mode A is no longer unstable for aspect ratios below 0.25, as the wake deviates further from the standard Bénard–von Kármán state. For still smaller aspect ratios, another three-dimensional quasi-periodic mode becomes unstable, leading to a different transition scenario. Interestingly, for the 0.25 aspect ratio case, mode A restabilises above a Reynolds number of approximately 125, allowing the wake to return to a two-dimensional state, at least in the near wake. For the flat plate, three-dimensional simulations show that the shift in the Strouhal number from the two-dimensional value is gradual with Reynolds number, unlike the situation for the circular cylinder wake once mode A shedding develops. Dynamic mode decomposition is used to characterise the spatially evolving character of the wake as it undergoes transition from the primary Bénard–von Kármán-like near wake into a two-layered wake, through to a secondary Bénard–von Kármán-like wake further downstream, which in turn develops an even longer wavelength unsteadiness. It is also used to examine the differences in the two- and three-dimensional near-wake state, showing the increasing distortion of the two-dimensional rollers as the Reynolds number is increased.

Vorticity generation and wake transition for a translating circular cylinder: Wall proximity and rotation effects

Publisher: Elsevier BV

Date: 11-2013

DOI: 10.1016/J.JWEIA.2013.06.009

Computed tomographic x-ray velocimetry

Publisher: AIP Publishing

Date: 11-01-2010

DOI: 10.1063/1.3285173

Abstract: An x-ray velocimetry technique is described which provides three components of velocity measurement in three dimensional space. Current x-ray velocimetry techniques, which use particle images taken at a single projection angle, are limited to two components of velocity measurement, and are unable to measure in three dimensions without a priori knowledge of the flow field. The proposed method uses multiple projection angles to overcome these limitations. The technique uses a least-squares iterative scheme to tomographically reconstruct the three-dimensional velocity field directly from two-dimensional image pair cross-correlations, without the need to reconstruct three-dimensional particle images. Synchrotron experiments demonstrate the effectiveness of the technique for blood flow measurement in opaque vessels, with applications for the diagnosis and treatment of cardiovascular disease.

Optimal growth of counter-rotating vortex pairs interacting with walls

Publisher: Cambridge University Press (CUP)

Date: 06-10-2016

DOI: 10.1017/JFM.2020.674

Direct numerical simulation of a counter-rotating vortex pair interacting with a wall

Publisher: Cambridge University Press (CUP)

Date: 17-12-2019

DOI: 10.1017/JFM.2019.816

Flow past rectangular cylinders: Receptivity to transverse forcing

Publisher: Cambridge University Press (CUP)

Date: 25-09-2004

DOI: 10.1017/S0022112004000242

An improved, free surface, topographic technique

Publisher: Springer Science and Business Media LLC

Date: 03-2006

DOI: 10.1007/BF03181568

The unsteady wake of a circular cylinder near a free surface

Publisher: Springer Science and Business Media LLC

Date: 2003

DOI: 10.1023/B:APPL.0000014926.99751.B1

Radial migration of preplanetary material: Implications for the accretion time scale problem

Publisher: Elsevier BV

Date: 10-1984

DOI: 10.1016/0019-1035(84)90136-2

Effects of flapping-motion profiles on insect-wing aerodynamics

Publisher: Cambridge University Press (CUP)

Date: 03-12-2019

DOI: 10.1017/JFM.2019.929

Particle image velocimetry and visualization of natural and forced flow around rectangular cylinders

Publisher: Cambridge University Press (CUP)

Date: 10-03-2003

DOI: 10.1017/S0022112002003439

Abstract: Particle image velocimetry (PIV) measurements and flow visualization in a water tunnel show that vortex shedding at the leading and trailing edges of rectangular cylinders can be simultaneously phase-locked to transverse velocity perturbations when the applied perturbation St p is close to an impinging leading-edge vortex/trailing-edge vortex shedding (ILEV/TEVS) frequency. The transverse perturbations, analogous to β-mode duct acoustic resonances, are generated through harmonic oscillations of the sidewalls. When this occurs, the leading-edge vortices are found always to pass the trailing edge at the same phase in the perturbation cycle regardless of the chord-to-thickness ( c / t ) ratio. Applying perturbations at an St p not equal to the natural global frequency also results in phase-locked vortex shedding from the leading edge, and a near wake with a frequency equal to the perturbation frequency. This is consistent with previous experimental findings. However, vortex shedding at the trailing edge is either weaker or non-existent. PIV results and flow visualization showed trailing-edge vortex growth was weaker because leading-edge vortices arrive at the trailing edge at a phase in the perturbation cycle where they interfere with trailing-edge shedding. The frequencies at which trailing-edge vortices form for different c / t ratios correspond to the natural ILEV/TEVS frequencies. As in the case of natural shedding, peaks in base suction occur when the leading-edge vortices pass the trailing edge at the phase in the perturbation cycle (and thus in the leading-edge shedding cycle) that allows strong trailing-edge shedding. This is the reason for the similarity in the St vs. c / t relationship for three seemingly different sets of experiments.

Transverse flow-induced vibrations of a sphere

Publisher: Cambridge University Press (CUP)

Date: 05-01-2018

DOI: 10.1017/JFM.2017.881

Abstract: Flow-induced vibration of an elastically mounted sphere was investigated computationally for the classic case where the sphere motion was constrained to move in a direction transverse to the free stream. This study, therefore, provides additional insight into, and comparison with, corresponding experimental studies of transverse motion, and distinction from numerical and experimental studies with specific constraints such as tethering (Williamson & Govardhan, J. Fluids Struct. , vol. 11, 1997, pp. 293–305) or motion in all three directions (Behara et al. , J. Fluid Mech. , vol. 686, 2011, pp. 426–450). Two sets of simulations were conducted by fixing the Reynolds number at $Re=300$ or 800 over the reduced velocity ranges $3.5\\leqslant U^{\\ast }\\leqslant 100$ and $3\\leqslant U^{\\ast }\\leqslant 50$ respectively. The reduced mass of the sphere was kept constant at $m_{r}=1.5$ for both sets. The flow satisfied the incompressible Navier–Stokes equations, while the coupled sphere motion was modelled by a spring–mass–d er system, with d ing set to zero. The sphere showed a highly periodic large- litude vortex-induced vibration response over a lower reduced velocity range at both Reynolds numbers considered. This response was designated as branch A, rather than the initial/upper or mode I/II branch, in order to allow it to be discussed independently from the observed experimental response at higher Reynolds numbers which shows both similarities and differences. At $Re=300$ , it occurred over the range $5.5\\leqslant U^{\\ast }\\leqslant 10$ , with a maximum oscillation litude of ${\\approx}0.4D$ . On increasing the Reynolds number to 800, this branch widened to cover the range $4.5\\leqslant U^{\\ast }\\leqslant 13$ and the oscillation litude increased (maximum litude ${\\approx}0.6D$ ). In terms of wake dynamics, within this response branch, two streets of interlaced hairpin-type vortex loops were formed behind the sphere. The upper and lower sets of vortex loops were disconnected, as were their accompanying tails. The wake maintained symmetry relative to the plane defined by the streamwise and sphere motion directions. The topology of this wake structure was analogous to that seen experimentally at higher Reynolds numbers by Govardhan & Williamson ( J. Fluid Mech. , vol. 531, 2005, pp. 11–47). At even higher reduced velocities, the sphere showed distinct oscillatory behaviour at both Reynolds numbers examined. At $Re=300$ , small but non-negligible oscillations were found to occur ( litude of ${\\approx}0.05D$ ) within the reduced velocity ranges $13\\leqslant U^{\\ast }\\leqslant 16$ and $26\\leqslant U^{\\ast }\\leqslant 100$ , named branch B and branch C respectively. Moreover, within these reduced velocity ranges, the centre of motion of the sphere shifted from its static position. In contrast, at $Re=800$ , the sphere showed an aperiodic intermittent mode IV vibration state immediately beyond branch A, for $U^{\\ast }\\geqslant 14$ . This vibration state was designated as the intermittent branch. Interestingly, the dominant frequency of the sphere vibration was close to the natural frequency of the system, as observed by Jauvtis et al. ( J. Fluids Struct. , vol. 15(3), 2001, pp. 555–563) in higher-mass-ratio higher-Reynolds-number experiments. The oscillation litude increased as the reduced velocity increased and reached a value of ${\\approx}0.9D$ at $U^{\\ast }=50$ . The wake was irregular, with multiple vortex shedding cycles during each cycle of sphere oscillation.

Self-sustained oscillations in flows around long blunt plates

Publisher: Elsevier BV

Date: 04-2001

DOI: 10.1006/JFLS.2000.0352

The influence of a small upstream wire on transition in a rotating cylinder wake

Publisher: Cambridge University Press (CUP)

Date: 25-03-2015

DOI: 10.1017/JFM.2015.152

Abstract: Recent experimental research on rotating cylinder wakes has found that a previously numerically predicted subharmonic instability mode, mode C, occurs for considerably lower rotation rates than predicted through stability analysis, yet other mode transitions occur closer to the predicted onset. One difference between the theoretical and experimental set-ups is the use of a small-diameter hydrogen bubble visualisation wire placed upstream of the rotating cylinder. The current paper tests the hypothesis that a wire, of only $1/100$ th of the cylinder diameter, placed five diameters upstream of the cylinder, sufficiently perturbs the flow to substantially affect certain wake transitions, including the onset of mode C. This is achieved using stability analysis of a flow that includes the upstream wire. The results indeed show that the wire of a tiny diameter induces a non-negligible asymmetry in the flow, triggering the subharmonic mode at substantially lower rotation rates. Furthermore, at higher rotation rates, the onset of two other three-dimensional modes are delayed to higher Reynolds numbers. These results make the point that even seemingly minute perturbations caused by minimally intrusive methods may result in substantially altered experimental flow behaviour.

The Lyman–Huggins interpretation of enstrophy transport

Publisher: Cambridge University Press (CUP)

Date: 06-03-2023

DOI: 10.1017/JFM.2023.95

Abstract: The Lighthill–Panton and Lyman–Huggins interpretations of vorticity dynamics are extended to the dynamics of enstrophy. There exist two competing definitions of the vorticity current tensor, which describes the flow rate of vorticity in the fluid interior, and the corresponding boundary vorticity flux, which represents the local vorticity creation rate on a boundary. It is demonstrated that each definition of the vorticity current tensor leads to a consistent set of definitions for the enstrophy current, boundary enstrophy flux and the enstrophy dissipation term. This leads to two alternative interpretations of vorticity and enstrophy dynamics: the Lighthill–Panton and Lyman–Huggins interpretations. Although the kinematic evolution of the vorticity and enstrophy fields are the same under each set of definitions, the dynamical interpretation of the motion generally differs. For ex le, we consider the Stokes flow over a rotating sphere, and find that the flow approaches a steady state where, under the Lyman–Huggins interpretation, there is no enstrophy creation or dissipation. Under the Lighthill–Panton interpretation, however, the steady-state flow features a balance between the continuous generation and subsequent dissipation of enstrophy. Moreover, the Lyman–Huggins interpretation has previously been shown to offer several benefits in understanding the dynamics of vorticity, and therefore it is beneficial to extend this interpretation to the dynamics of enstrophy. For ex le, the Lyman–Huggins interpretation allows the creation of vorticity, and therefore enstrophy, to be interpreted as an inviscid process, due to the relative acceleration between the fluid and the boundary.

Experimental control of vortex breakdown by density effects

Publisher: AIP Publishing

Date: 03-2011

DOI: 10.1063/1.3560386

Abstract: The vortex breakdown inside a cylinder with a rotating top lid is controlled experimentally by injecting at the bottom a fluid with a small density difference. The density difference is obtained by mixing a heavy dye or alcohol with water in order to create a jet denser or lighter than water. The injection of a heavy fluid creates a buoyancy force downward, which counteracts the meridional recirculation in the cylinder and thus enhances the formation of a vortex breakdown bubble. The stability diagram shows that even a very small density difference of 0.02% is able to decrease by a factor of 2 the critical Reynolds number of appearance of the breakdown. On the other hand, the injection of a lighter fluid does not destroy the vortex breakdown. However, for large enough density differences (larger than 0.03%), the lighter fluid is able to pierce through the bubble and leads to a new structure of the vortex breakdown. Finally, a parallel is drawn between a light jet and a vortex ring generated at the bottom of the cylinder: strong vortex rings are able to pierce through the bubble, whereas weak vortex rings are simply advected around the bubble.

Vortex dynamics and vibration modes of a tethered sphere

Publisher: Cambridge University Press (CUP)

Date: 18-12-2019

DOI: 10.1017/JFM.2019.928

Dynamics of the flow around colliding spheres

Publisher: Elsevier BV

Date: 11-2011

DOI: 10.1016/J.JFLUIDSTRUCTS.2011.05.003

LONGITUDINAL VORTEX STRUCTURES IN A CYLINDER WAKE

Publisher: AIP Publishing

Date: 09-1994

DOI: 10.1063/1.868115

Abstract: This paper presents the velocity field of the longitudinal vortices found in the wake of a circular cylinder, as measured using digital particle image velocimetry (PIV). Vorticity and circulation of the longitudinal vortices are presented, based on instantaneous velocity distributions in a transverse plane behind the cylinder.

Two-and three-dimensional wake transitions of a NACA0012 airfoil

Publisher: Cambridge University Press (CUP)

Date: 06-01-2023

DOI: 10.1017/JFM.2022.958

Abstract: Flow transitions are an important fluid-dynamic phenomena for many reasons, including the direct effect on the aerodynamic forces acting on the body. In the present study, two-dimensional (2-D) and three-dimensional (3-D) wake transitions of a NACA0012 airfoil are studied for angles of attack in the range $0^\\circ \\leq \\alpha \\leq 20^\\circ$ and Reynolds numbers $500 \\leq {\\textit {Re}} \\leq 5000$ . The study uses water-channel experiments and 2-D and 3-D numerical simulations based on the nodal spectral-element method, level-set function-based immersed-interface method and Floquet stability analysis. The different wake states are categorised based on the time-instantaneous wake structure, non-dimensional frequency and aerodynamic force coefficients. The wake states and transition boundaries are summarised in a wake regime map. The critical angle of attack and Reynolds number for the supercritical Hopf bifurcation (i.e. steady to periodic wake transition) varies as $\\alpha _1 {\\sim} {\\textit {Re}}^{-0.65}$ , while the critical angle of attack for the onset of three dimensionality varies as $\\alpha _{3D} {\\sim} {\\textit {Re}}^{-0.5}$ . Over the entire Reynolds number range, the transition to 3-D flow occurs through a mode C (subharmonic) transition. Beyond this initial transition, further instabilities of the 2-D periodic base flow arise and are investigated. For instance, at $ {\\textit {Re}}=2000$ and $\\alpha _{3D,2}=11.0^\\circ$ , mode C coexists together with modes related to modes A and QP seen in a stationary circular cylinder wake. In contrast, at $ {\\textit {Re}}=5000$ and $\\alpha _{3D,2}=8.0^\\circ$ , the dominant mode C coexists with mode QP. Three-dimensional simulations well beyond critical angles indicate that 2-D vortex-street transitions are approximately maintained in the fully saturated 3-D wakes in a spanwise-averaged sense.

Vortex structures in the wake of a buoyant tethered cylinder at moderate to high reduced velocities

Publisher: Elsevier BV

Date: 2004

DOI: 10.1016/J.EUROMECHFLU.2003.05.003

Convective instability in steady stenotic flow: optimal transient growth and experimental observation

Publisher: Cambridge University Press (CUP)

Date: 16-04-2010

DOI: 10.1017/S0022112010001229

Abstract: An optimal transient growth analysis is compared with experimental observation for the steady flow through an abrupt, axisymmetric stenosis of varying stenosis degree. Across the stenosis range, a localized sinuous convective shear-layer instability type is predicted to dominate. A comparison of the shape and development of the optimal modes is made with experimental dye visualizations. The presence of the same sinuous-type disturbance immediately upstream of the highly chaotic region observed in the experimental flow is consistent with the optimal growth predictions. This, together with the fact that the flow is unstable globally only at much higher Reynolds numbers, suggests bypass transition.

Predicted low frequency structures in the wake of elliptical cylinders

Publisher: Elsevier BV

Date: 2004

DOI: 10.1016/J.EUROMECHFLU.2003.05.006

Optimisation of a Stirred Bioreactor through the Use of a Novel Holographic Correlation Velocimetry Flow Measurement Technique

Publisher: Public Library of Science (PLoS)

Date: 11-06-2013

DOI: 10.1371/JOURNAL.PONE.0065714

Role of Shape and Kinematics in the Hydrodynamics of a Fish-like Oscillating Hydrofoil

Publisher: MDPI AG

Date: 05-10-2023

DOI: 10.3390/JMSE11101923

Dynamic response of elliptical cylinders undergoing transverse flow-induced vibration

Publisher: Elsevier BV

Date: 08-2019

DOI: 10.1016/J.JFLUIDSTRUCTS.2019.01.011

Development of dual‐triggered in situ gelling scaffolds for tissue engineering

Publisher: Wiley

Date: 18-03-2014

DOI: 10.1002/PI.4704

Dye visualization near a three-dimensional stagnation point: application to the vortex breakdown bubble

Publisher: Cambridge University Press (CUP)

Date: 10-03-2009

DOI: 10.1017/S0022112008005107

Abstract: An analytical model, based on the Fokker–Planck equation, is constructed of the dye visualization expected near a three-dimensional stagnation point in a swirling fluid flow. The model is found to predict dye traces that oscillate in density and position in the meridional plane in which swirling flows are typically visualized. Predictions based on the model are made for the steady vortex breakdown bubble in a torsionally driven cylinder and compared with computational fluid dynamics predictions and experimental observations. Previous experimental observations using tracer visualization techniques have suggested that even for low-Reynolds-number flows, the steady vortex breakdown bubble in a torsionally driven cylinder is not axisymmetric and has an inflow/outflow asymmetry at its tail. Recent numerical and theoretical studies show that the asymmetry of the vortex breakdown bubble, and consequently its open nature, can be explained by the very small imperfections that are present in any experimental rig. Distinct from this, here it is shown that even for a perfectly axisymmetric flow and breakdown bubble, the combined effect of dye diffusion and the inevitable small errors in the dye injection position lead to the false perception of an open bubble structure with folds near the lower stagnation point. Furthermore, the asymmetries in the predicted flow structures can be remarkably similar to those observed in flow observations and computational predictions with geometric asymmetries of the rig. Thus, when interpreting dye-visualization patterns in steady flow, even if axisymmetric flow can be achieved, it is important to take into account the relative diffusivity of the dye and the accuracy of its injection.

Target-free Stereo PIV: a novel technique with inherent error estimation and improved accuracy

Publisher: Springer Science and Business Media LLC

Date: 19-10-2007

DOI: 10.1007/S00348-007-0404-1

The effect of imposed rotary oscillation on the flow-induced vibration of a sphere

Publisher: Cambridge University Press (CUP)

Date: 19-09-2018

DOI: 10.1017/JFM.2018.667

Abstract: This experimental study investigates the effect of imposed rotary oscillation on the flow-induced vibration of a sphere that is elastically mounted in the cross-flow direction, employing simultaneous displacement, force and vorticity measurements. The response is studied over a wide range of forcing parameters, including the frequency ratio $f_{R}$ and velocity ratio $\\unicode[STIX]{x1D6FC}_{R}$ of the oscillatory forcing, which vary between $0\\leqslant f_{R}\\leqslant 5$ and $0\\leqslant \\unicode[STIX]{x1D6FC}_{R}\\leqslant 2$ . The effect of another important flow parameter, the reduced velocity, $U^{\\ast }$ , is also investigated by varying it in small increments between $0\\leqslant U^{\\ast }\\leqslant 20$ , corresponding to the Reynolds number range of $5000\\lesssim Re\\lesssim 30\\,000$ . It has been found that when the forcing frequency of the imposed rotary oscillations, $f_{r}$ , is close to the natural frequency of the system, $f_{nw}$ , (so that $f_{R}=f_{r}/f_{nw}\\sim 1$ ), the sphere vibrations lock on to $f_{r}$ instead of $f_{nw}$ . This inhibits the normal resonance or lock-in leading to a highly reduced vibration response litude. This phenomenon has been termed ‘rotary lock-on’, and occurs for only a narrow range of $f_{R}$ in the vicinity of $f_{R}=1$ . When rotary lock-on occurs, the phase difference between the total transverse force coefficient and the sphere displacement, $\\unicode[STIX]{x1D719}_{total}$ , jumps from $0^{\\circ }$ (in phase) to $180^{\\circ }$ (out of phase). A corresponding dip in the total transverse force coefficient $C_{y\\,(rms)}$ is also observed. Outside the lock-on boundaries, a highly modulated litude response is observed. Higher velocity ratios ( $\\unicode[STIX]{x1D6FC}_{R}\\geqslant 0.5$ ) are more effective in reducing the vibration response of a sphere to much lower values. The mode I sphere vortex-induced vibration (VIV) response is found to resist suppression, requiring very high velocity ratios ( $\\unicode[STIX]{x1D6FC}_{R} .5$ ) to significantly suppress vibrations for the entire range of $f_{R}$ tested. On the other hand, mode II and mode III are suppressed for $\\unicode[STIX]{x1D6FC}_{R}\\geqslant 1$ . The width of the lock-on region increases with an increase in $\\unicode[STIX]{x1D6FC}_{R}$ . Interestingly, a reduction of VIV is also observed in non-lock-on regions for high $f_{R}$ and $\\unicode[STIX]{x1D6FC}_{R}$ values. For a fixed $\\unicode[STIX]{x1D6FC}_{R}$ , when $U^{\\ast }$ is progressively increased, the response of the sphere is very rich, exhibiting characteristically different vibration responses for different $f_{R}$ values. The phase difference between the imposed rotary oscillation and the sphere displacement $\\unicode[STIX]{x1D719}_{rot}$ is found to be crucial in determining the response. For selected $f_{R}$ values, the vibration litude increases monotonically with an increase in flow velocity, reaching magnitudes much higher than the peak VIV response for a non-rotating sphere. For these cases, the vibrations are always locked to the forcing frequency, and there is a linear decrease in $\\unicode[STIX]{x1D719}_{rot}$ . Such vibrations have been termed ‘rotary-induced vibrations’. The wake measurements in the cross-plane $1.5D$ downstream of the sphere position reveal that the sphere wake consists of vortex loops, similar to the wake of a sphere without any imposed rotation however, there is a change in the timing of vortex formation. On the other hand, for high $f_{R}$ values, there is a reduction in the streamwise vorticity, presumably leading to a decreased total transverse force acting on the sphere and resulting in a reduced response.

Erratum to “Unsteady flow around impacting bluff bodies” [J. Fluids Struct. 24 (2008) 1194–1203]

Publisher: Elsevier BV

Date: 04-2009

DOI: 10.1016/J.JFLUIDSTRUCTS.2008.12.001

The wake dynamics of a cylinder moving along a planewall with rotation and translation

Publisher: Springer Netherlands

Date: 2009

DOI: 10.1007/978-1-4020-9898-7_43

Numerical simulations of the flow-induced vibrations of tethered bluff bodies

Publisher: ASMEDC

Date: 2002

DOI: 10.1115/IMECE2002-32168

Abstract: One of the most basic ex les of fluid-structure interaction is provided by a tethered cylinder or sphere in a fluid flow. The tendency of a tethered sphere to oscillate when excited by waves is a well-known phenomenon and it has only recently been found that the same system will act in a similar fashion when exposed to a uniform flow at moderate Reynolds numbers, with a transverse peak-to-peak litude of approximately two diameters over a wide range of velocities. The present paper presents results of DNS of the flow past a tethered cylinder. The coupled Navier-Stokes equations and the equations of motion of the cylinder are solved using a spectral element method. The fluid forces acting on the cylinder as well as the tension in the tether are computed and used to determine the resulting motion of the object. It is found that the mean litude response is greatest at high reduced velocities, i.e. when the cylinder is oscillating predominantly transverse to the fluid flow. Furthermore, the oscillation frequency is found to correspond to the vortex shedding frequency of a stationary cylinder, except at high reduced velocities. This is in contrast to a tethered sphere in which the oscillation frequency does not correspond to either the vortex shedding frequency or the natural frequency. Visualizations of the vortex structures in the wake reveal the mechanisms behind the motion of the cylinder, and suggest that the induced oscillations are highly significant in the prediction of cylinder response in a steady flow.

Clinical and Experimental Pharmacology and Physiology: Introduction

Publisher: Wiley

Date: 02-2009

DOI: 10.1111/J.1440-1681.2008.05096.X

The beginning of branching behaviour of vortex-induced vibration during two-dimensional flow

Publisher: Elsevier BV

Date: 08-2006

DOI: 10.1016/J.JFLUIDSTRUCTS.2006.04.003

Low-level flow-induced acoustic resonances in ducts

Publisher: IOP Publishing

Date: 09-1988

DOI: 10.1016/0169-5983(88)90091-3

Vortex ring connection to a free surface

Publisher: Cambridge University Press (CUP)

Date: 07-07-2022

DOI: 10.1017/JFM.2022.529

Abstract: We perform numerical simulations of the interaction between a vortex ring and a free surface, and provide a new interpretation of the mechanism by which the vortex ring connects to the free surface. Large vorticity gradients at the free surface result in the diffusion of surface-tangential vorticity out of the fluid. This is accompanied by the diffusion of opposite-signed surface-normal vorticity away from the connection line, along the free surface, which results in the attachment of the vortex ring to the free surface. Compared to existing descriptions, this interpretation explains better how the solenoidal property that vortex lines do not end in the fluid is maintained. By including an interface vortex sheet at the free surface, the important property of vorticity conservation is maintained throughout the interaction. The upper part of the vortex ring simply diffuses out of the fluid, and into the interface vortex sheet, with the total circulation remaining constant.

Vortex-induced vibration of a transversely rotating sphere

Publisher: Cambridge University Press (CUP)

Date: 29-05-2018

DOI: 10.1017/JFM.2018.309

Abstract: The effects of transverse rotation on the vortex-induced vibration (VIV) of a sphere in a uniform flow are investigated numerically. The one degree-of-freedom sphere motion is constrained to the cross-stream direction, with the rotation axis orthogonal to flow and vibration directions. For the current simulations, the Reynolds number of the flow, $Re=UD/\\unicode[STIX]{x1D708}$ , and the mass ratio of the sphere, $m^{\\ast }=\\unicode[STIX]{x1D70C}_{s}/\\unicode[STIX]{x1D70C}_{f}$ , were fixed at 300 and 2.865, respectively, while the reduced velocity of the flow was varied over the range $3.5\\leqslant U^{\\ast }~(\\equiv U/(f_{n}D))\\leqslant 11$ , where, $U$ is the upstream velocity of the flow, $D$ is the sphere diameter, $\\unicode[STIX]{x1D708}$ is the fluid viscosity, $f_{n}$ is the system natural frequency and $\\unicode[STIX]{x1D70C}_{s}$ and $\\unicode[STIX]{x1D70C}_{f}$ are solid and fluid densities, respectively. The effect of sphere rotation on VIV was studied over a wide range of non-dimensional rotation rates: $0\\leqslant \\unicode[STIX]{x1D6FC}~(\\equiv \\unicode[STIX]{x1D714}D/(2U))\\leqslant 2.5$ , with $\\unicode[STIX]{x1D714}$ the angular velocity. The flow satisfied the incompressible Navier–Stokes equations while the coupled sphere motion was modelled by a spring–mass–d er system, under zero d ing. For zero rotation, the sphere oscillated symmetrically through its initial position with a maximum litude of approximately 0.4 diameters. Under forced rotation, it oscillated about a new time-mean position. Rotation also resulted in a decreased oscillation litude and a narrowed synchronisation range. VIV was suppressed completely for $\\unicode[STIX]{x1D6FC} .3$ . Within the $U^{\\ast }$ synchronisation range for each rotation rate, the drag force coefficient increased while the lift force coefficient decreased from their respective pre-oscillatory values. The increment of the drag force coefficient and the decrement of the lift force coefficient reduced with increasing reduced velocity as well as with increasing rotation rate. In terms of wake dynamics, in the synchronisation range at zero rotation, two equal-strength trails of interlaced hairpin-type vortex loops were formed behind the sphere. Under rotation, the streamwise vorticity trail on the advancing side of the sphere became stronger than the trail in the retreating side, consistent with wake deflection due to the Magnus effect. This symmetry breaking appears to be associated with the reduction in the observed litude response and the narrowing of the synchronisation range. In terms of variation with Reynolds number, the sphere oscillation litude was found to increase over the range $Re\\in [300,1200]$ at $U^{\\ast }=6$ for each of $\\unicode[STIX]{x1D6FC}=0.15$ , 0.75 and 1.5. The VIV response depends strongly on Reynolds number, with predictions indicating that VIV will persist for higher rotation rates at higher Reynolds numbers.

Wake transition of a rolling sphere

Publisher: Springer Science and Business Media LLC

Date: 11-2010

DOI: 10.1007/S12650-010-0061-Y

The generation and conservation of vorticity: deforming interfaces and boundaries in two-dimensional flows

Publisher: Cambridge University Press (CUP)

Date: 10-03-2020

DOI: 10.1017/JFM.2020.128

Simulations of aeroelasticity in an annular cascade using a parallel 3-dimensional Navier-Stokes solver

Publisher: ASMEDC

Date: 2002

DOI: 10.1115/GT2002-30366

Abstract: A parallel multi-block Navier-Stokes solver with the k-ω turbulence model is developed to simulate the 3-dimensional unsteady flow through an annular turbine cascade. Results at mid-span are compared with the experimental results of Standard Test Case 4. Comparisons are made between 3-dimensional and 2-dimensional, and inviscid and viscous simulations. The inclusion of a viscous flow model does not greatly affect the stability of the configuration.

Efficient FSI solvers for multiple-degrees-of-freedom flow-induced vibration of a rigid body

Publisher: Elsevier BV

Date: 2020

DOI: 10.1016/J.COMPFLUID.2019.104340

The past, present, and future of x-ray technology for in vivo imaging of function and form

Publisher: AIP Publishing

Date: 15-05-2009

DOI: 10.1063/1.3115643

Abstract: Scientists and clinicians have a keen interest in studying not just the structure of physiological systems, but their motion also, or more generally their form and function. This paper focuses on the technologies that underpin in vivo measurements of form and function of the human body for both research and medical treatment. A concise literature review of x-ray imaging, ultrasonography, magnetic resonance imaging, radionuclide imaging, laser Doppler velocimetry, and particle image velocimetry is presented. Additionally, a more detailed review of in vivo x-ray imaging is presented. Finally, two techniques, which the authors believe are representative of the present and future of in vivo x-ray imaging techniques, are presented.

Optimisation of temporal averaging processes in PIV

Publisher: Springer Science and Business Media LLC

Date: 04-2011

DOI: 10.1007/S00348-011-1080-8

Three-dimensional vortex structures in a cylinder wake

Publisher: Cambridge University Press (CUP)

Date: 10-04-1996

DOI: 10.1017/S0022112096001978

Abstract: The three-dimensionality of the velocity field in the wake of a circular cylinder has excited considerable interest and debate over the past decade. Presented here are experimental results that characterize the underlying vorticity field of such wakes. Using particle image velocimetry (PIV), instantaneous velocity fields were measured and from these the vorticity of the longitudinal vortices lying in the region between Kármán vortices was found. Near the saddle point, induced by the stretching of the Kármán vortices, the vorticity of the longitudinal vortices was found to be greater than the Kármán vortices themselves. Their circulation was of the order of 10% of the Kármán vortices. The high levels of vorticity result from the stretching of the longitudinal vortices, as evident in the topology of the vortices. It is shown that the longitudinal vortices are locked in phase to the KármánK vortices, effectively riding on their backs in the braid region. While only one mode of longitudinal vortex formation was observed, evidence was found of a step change in the vorticity levels at a Reynolds number of approximately 200. This is consistent with the transition point between the two modes of vortex shedding shown to exist by Williamson (1988). It had previously been proposed that the observed vortex patterns were consistent with the evolution of the longitudinal vortices from perturbations of vortex lines in the separating shear layer which experience self-induction and stretching from the Kármán vortices. Evidence is presented that supports this model.

Shear layer vortices and longitudinal vortices in the near wake of a circular cylinder

Publisher: Elsevier BV

Date: 02-1996

DOI: 10.1016/0894-1777(95)00087-9

Three-dimensional instabilities in the wake of a circular cylinder

Publisher: Elsevier BV

Date: 02-1996

DOI: 10.1016/0894-1777(95)00098-4

Vorticity generation and conservation for two-dimensional interfaces and boundaries – ERRATUM

Publisher: Cambridge University Press (CUP)

Date: 29-05-2020

DOI: 10.1017/JFM.2020.357

Vorticity generation and conservation for two-dimensional interfaces and boundaries

Publisher: Cambridge University Press (CUP)

Date: 07-10-2014

DOI: 10.1017/JFM.2014.520

Abstract: The generation, redistribution and, importantly, conservation of vorticity and circulation is studied for incompressible Newtonian fluids in planar and axisymmetric geometries. A generalised formulation of the vorticity at the interface between two fluids for both no-slip and stress-free conditions is presented. Illustrative ex les are provided for planar Couette flow, Poiseuille flow, the spin-up of a circular cylinder, and a cylinder below a free surface. For the last ex le, it is shown that, although large imbalances between positive and negative vorticity appear in the wake, the balance is found in the vortex sheet representing the stress-free surface.

Evaluating fluid forces on bluff bodies using partial velocity data

Publisher: Elsevier BV

Date: 2005

DOI: 10.1016/J.JFLUIDSTRUCTS.2004.08.002

Editorial: Biomedical Engineering Imaging

Publisher: Bentham Science Publishers Ltd.

Date: 08-2012

DOI: 10.2174/138920112802502006

Altered lung motion is a sensitive indicator of regional lung disease

Publisher: Springer Science and Business Media LLC

Date: 22-12-2012

DOI: 10.1007/S10439-011-0493-0

Abstract: Since lung diseases adversely affect airflow during breathing, they must also alter normal lung motion, which can be exploited to detect these diseases. However, standard imaging techniques such as CT and MRI imaging during breath-holds provide little or no information on lung motion and cannot detect diseases that cause subtle changes in lung structure. Phase-contrast X-ray imaging provides images of high contrast and spatial resolution with temporal resolutions that allow multiple images to be acquired throughout the respiratory cycle. Using X-ray phase-contrast imaging, coupled with velocimetry, we have measured lung tissue movement and determined velocity fields that define speed and direction of regional lung motion throughout a breath in normal Balb/c nude male mice and mice exposed to bleomycin. Regional maps of lung tissue motion reveal both the heterogeneity of normal lung motion, as well as abnormal motion induced by bleomycin treatment. Analysed histologically, bleomycin treatment caused pathological changes in lung structure that were heterogenous, occupying less than 12% of the lung at 6 days after treatment. Moreover, plethysmography failed to detect significant changes in compliance at either 36 h or 6 days after treatment. Detailed analysis of the vector fields demonstrated major differences (p < 0.001) in regional lung motion between control and bleomycin-treated mice at both 36 h and 6 days after treatment. The results of this study demonstrate that X-ray phase-contrast imaging, coupled with velocimetry, can detect early stage, subtle and non-uniform lung disease.

Unsteady separated flows and their control

Publisher: Elsevier BV

Date: 11-2008

DOI: 10.1016/J.JFLUIDSTRUCTS.2008.08.004

Unsteady flow around impacting bluff bodies

Publisher: Elsevier BV

Date: 11-2008

DOI: 10.1016/J.JFLUIDSTRUCTS.2008.08.003

Sound generated by a pair of axisymmetric coaxial vortex rings

Publisher: American Institute of Aeronautics and Astronautics (AIAA)

Date: 02-2005

DOI: 10.2514/1.5797

Modification of the flow structures in a swirling jet

Publisher: Springer Netherlands

Date: 2009

DOI: 10.1007/978-1-4020-9898-7_21

A numerical study of global frequency selection in the time-mean wake of a circular cylinder

Publisher: Cambridge University Press (CUP)

Date: 04-02-2010

DOI: 10.1017/S0022112009993132

Abstract: A series of direct numerical simulations, both in two- and three-dimensions, of the flow past a circular cylinder for Reynolds numbers Re ≤ 600 has been conducted. From these simulations, the time-mean (and, for the three-dimensional simulations, the spanwise spatial-mean) flow has been calculated. A global linear stability analysis has been conducted on these mean flows, showing that the mean cylinder wake for Re ≤ 600 is marginally stable and the eigenfrequency of the leading global mode closely predicts the eventual saturated vortex shedding frequency. A local stability analysis has also been conducted. For this, a series of streamwise velocity profiles has been extracted from the mean wake and the stability of these profiles has been analysed using the Rayleigh stability equation. The real and imaginary instability frequencies gained from these profiles have then been used to find the global frequency selected by the flow using a saddle-point criterion. The results confirm the success of the saddle-point criterion when the mean flow is quasi-parallel in the vicinity of the saddle point however, the limitations of the method when the mean flow exhibits higher curvature are also elucidated.

Vortex dynamics associated with the impact of a cylinder with a wall

Publisher: Springer Netherlands

Date: 2009

DOI: 10.1007/978-1-4020-9898-7_20

Myocardial infarction: stem cell transplantation for cardiac regeneration

Publisher: Future Medicine Ltd

Date: 11-2015

DOI: 10.2217/RME.15.63

Abstract: It is estimated that by 2030, almost 23.6 million people will perish from cardiovascular disease, according to the WHO. The review discusses advances in stem cell therapy for myocardial infarction, including cell sources, methods of differentiation, expansion selection and their route of delivery. Skeletal muscle cells, hematopoietic cells and mesenchymal stem cells (MSCs) and embryonic stem cells (ESCs)-derived cardiomyocytes have advanced to the clinical stage, while induced pluripotent cells (iPSCs) are yet to be considered clinically. Delivery of cells to the sites of injury and their subsequent retention is a major issue. The development of supportive scaffold matrices to facilitate stem cell retention and differentiation are analyzed. The review outlines clinical translation of conjugate stem cell-based cellular therapeutics post-myocardial infarction.

The leading-edge vortex on a rotating wing changes markedly beyond a certain central body size

Publisher: The Royal Society

Date: 07-2018

DOI: 10.1098/RSOS.172197

Abstract: Stable attachment of a leading-edge vortex (LEV) plays a key role in generating the high lift on rotating wings with a central body. The central body size can affect the LEV structure broadly in two ways. First, an overall change in the size changes the Reynolds number, which is known to have an influence on the LEV structure. Second, it may affect the Coriolis acceleration acting across the wing, depending on the wing-offset from the axis of rotation. To investigate this, the effects of Reynolds number and the wing-offset are independently studied for a rotating wing. The three-dimensional LEV structure is mapped using a scanning particle image velocimetry technique. The rapid acquisition of images and their correlation are carefully validated. The results presented in this paper show that the LEV structure changes mainly with the Reynolds number. The LEV-split is found to be only minimally affected by changing the central body radius in the range of small offsets, which interestingly includes the range for most insects. However, beyond this small offset range, the LEV-split is found to change dramatically.

Experimental study of simultaneous measurement of velocity and surface topography: In the wake of a circular cylinder at low Reynolds number

Publisher: Springer Science and Business Media LLC

Date: 22-08-2011

DOI: 10.1007/S00348-010-0960-7

Evolution and rupture of vulnerable plaques: a review of mechanical effects

Publisher: Informa UK Limited

Date: 04-2013

DOI: 10.2147/CPT.S32050

Microfluidic Manipulation of Core/Shell Nanoparticles for Oral Delivery of Chemotherapeutics: A New Treatment Approach for Colorectal Cancer

Publisher: Wiley

Date: 22-03-2016

DOI: 10.1002/ADMA.201502697

Large deformations of elastic vessels under atherosclerotic conditions

Publisher: AIP Publishing LLC

Date: 2015

DOI: 10.1063/1.4913142

The shedding of vorticity from a smooth surface

Publisher: IOP Publishing

Date: 09-1988

DOI: 10.1016/0169-5983(88)90054-8

From spheres to circular cylinders: the stability and flow structures of bluff ring wakes

Publisher: Cambridge University Press (CUP)

Date: 10-10-2003

DOI: 10.1017/S0022112003005512

Global frequency selection in the observed time-mean wakes of circular cylinders

Publisher: Cambridge University Press (CUP)

Date: 25-04-2008

DOI: 10.1017/S0022112008000785

Abstract: Observations have been made of the time-mean velocity profile at midspan in the near-wake of circular cylinders at moderate Reynolds numbers between 600 and 4600, well beyond the Reynolds number of approximately 200 at which the wake becomes three-dimensional. The measured profiles are found to be represented quite accurately by a family of function profiles with known linear instability characteristics. The complex instability frequency is then determined as a function of wake position, using the function profiles. In general, the near wake undergoes a transition from convective to absolute instability the distance downstream to the point of transition is found to increase over the Reynolds number range investigated. The emergence of a significant region of convective instability is consistent with the known appearance of Bloor–Gerrard vortices. The selected frequency of the wake instability is determined by the saddle-point criterion the Strouhal numbers for Bénard–von Kármán vortex shedding are found to compare well with the values in the literature.

The generation and diffusion of vorticity in three-dimensional flows: Lyman's flux

Publisher: Cambridge University Press (CUP)

Date: 25-03-2021

DOI: 10.1017/JFM.2021.179

Acoustics and experimental methods: The influence of sound on flow and heat transfer

Publisher: Elsevier BV

Date: 1990

DOI: 10.1016/0894-1777(90)90106-H

European Journal of Mechanics, B/Fluids: Preface

Publisher: Elsevier BV

Date: 2004

DOI: 10.1016/J.EUROMECHFLU.2003.10.001

A coupled Landau model describing the Strouhal - Reynolds number profile of a three-dimensional circular cylinder wake

Publisher: AIP Publishing

Date: 23-07-2003

DOI: 10.1063/1.1597471

Abstract: A known bifurcation scenario describing the development and interaction of Mode A and Mode B vortex shedding modes of a circular cylinder wake is extended to predict the Strouhal–Reynolds number profile over the three-dimensional transitions. The mode litudes are described by coupled Landau equations and, with frequency information being included by the addition of complex coefficients, the model predicts the discontinuous nature of the Strouhal–Reynolds number shedding profile of the circular cylinder wake throughout the laminar three-dimensional transition regime. The model coefficients are determined from computations of the three-dimensional modes of a circular cylinder wake.

Vortex-induced vibration of a rotating sphere

Publisher: Cambridge University Press (CUP)

Date: 20-12-2018

DOI: 10.1017/JFM.2017.847

Abstract: Vortex-induced vibration (VIV) of a sphere represents one of the most generic fundamental fluid–structure interaction problems. Since vortex-induced vibration can lead to structural failure, numerous studies have focused on understanding the underlying principles of VIV and its suppression. This paper reports on an experimental investigation of the effect of imposed axial rotation on the dynamics of vortex-induced vibration of a sphere that is free to oscillate in the cross-flow direction, by employing simultaneous displacement and force measurements. The VIV response was investigated over a wide range of reduced velocities (i.e. velocity normalised by the natural frequency of the system): $3\leqslant U^{\ast }\leqslant 18$ , corresponding to a Reynolds number range of $5000 Re \,000$ , while the rotation ratio, defined as the ratio between the sphere surface and inflow speeds, $\unicode[STIX]{x1D6FC}=|\unicode[STIX]{x1D714}|D/(2U)$ , was varied in increments over the range of $0\leqslant \unicode[STIX]{x1D6FC}\leqslant 7.5$ . It is found that the vibration litude exhibits a typical inverted bell-shaped variation with reduced velocity, similar to the classic VIV response for a non-rotating sphere but without the higher reduced velocity response tail. The vibration litude decreases monotonically and gradually as the imposed transverse rotation rate is increased up to $\unicode[STIX]{x1D6FC}=6$ , beyond which the body vibration is significantly reduced. The synchronisation regime, defined as the reduced velocity range where large vibrations close to the natural frequency are observed, also becomes narrower as $\unicode[STIX]{x1D6FC}$ is increased, with the peak saturation litude observed at progressively lower reduced velocities. In addition, for small rotation rates, the peak litude decreases almost linearly with $\unicode[STIX]{x1D6FC}$ . The imposed rotation not only reduces vibration litudes, but also makes the body vibrations less periodic. The frequency spectra revealed the occurrence of a broadband spectrum with an increase in the imposed rotation rate. Recurrence analysis of the structural vibration response demonstrated a transition from periodic to chaotic in a modified recurrence map complementing the appearance of broadband spectra at the onset of bifurcation. Despite considerable changes in flow structure, the vortex phase ( $\unicode[STIX]{x1D719}_{vortex}$ ), defined as the phase between the vortex force and the body displacement, follows the same pattern as for the non-rotating case, with the $\unicode[STIX]{x1D719}_{vortex}$ increasing gradually from low values in Mode I of the sphere vibration to almost $180^{\circ }$ as the system undergoes a continuous transition to Mode II of the sphere vibration at higher reduced velocity. The total phase ( $\unicode[STIX]{x1D719}_{total}$ ), defined as the phase between the transverse lift force and the body displacement, only increases from low values after the peak litude response in Mode II has been reached. It reaches its maximum value ( ${\sim}165^{\circ }$ ) close to the transition from the Mode II upper plateau to the lower plateau, reminiscent of the behaviour seen for the upper to lower branch transition for cylinder VIV. Hydrogen-bubble visualisations and particle image velocimetry (PIV) performed in the equatorial plane provided further insights into the flow dynamics near the sphere surface. The mean wake is found to be deflected towards the advancing side of the sphere, associated with an increase in the Magnus force. For higher rotation ratios, the near-wake rear recirculation zone is absent and the flow is highly vectored from the retreating side to the advancing side, giving rise to large-scale shedding. For a very high rotation ratio of $\unicode[STIX]{x1D6FC}=6$ , for which vibrations are found to be suppressed, a one-sided large-scale shedding pattern is observed, similar to the shear-layer instability one-sided shedding observed previously for a rigidly mounted rotating sphere.

Advances in Fluid-Structure interaction involving critical flow dynamics around moving deformable structures with impact on design applications

Publisher: Elsevier BV

Date: 11-2019

DOI: 10.1016/J.JFLUIDSTRUCTS.2019.102796

Modelling the transport of momentum and oxygen in an aerial-disk driven bioreactor used for animal tissue or cell culture

Publisher: Springer Berlin Heidelberg

Date: 2009

DOI: 10.1007/978-3-540-92841-6_415

Host–microbe interactions have shaped the genetic architecture of inflammatory bowel disease

Publisher: Springer Science and Business Media LLC

Date: 31-10-2012

DOI: 10.1038/NATURE11582

The wake and thrust by four side-by-side cylinders at a low Re

Publisher: Elsevier BV

Date: 04-2017

DOI: 10.1016/J.JFLUIDSTRUCTS.2017.01.014

Aspect ratio studies on insect wings

Publisher: AIP Publishing

Date: 12-2019

DOI: 10.1063/1.5129191

Abstract: The wing aspect ratio (AR), that is, the ratio of the wingspan to the mean wing chord, is the most important geometrical parameter describing an insect wing. While studies have shown that a change in AR affects the flow structure as well as the aerodynamic force components on wings, the reasons behind the wide variety of aspect ratios observed in nature remain underexplored. Further to this, motivated by the developments in micro-air vehicles (MAVs), determining an optimum AR is important for their efficient operation. While the effects on flow structure appear to be, at least superficially, broadly consistent across different studies, the effects on aerodynamic forces have been more strongly debated. Indeed, the considerable variation of force coefficients with AR in different studies suggests different optimal ARs. To help explain this, recent studies have pointed out the coupled effects of AR with other parameters. Specifically, the use of Reynolds and Rossby numbers based on alternative scalings helps to at least partially decouple the effects of AR and also to reconcile previous conflicting trends. This brief review presents an overview of previous studies on aspect-ratio effects of insectlike wings summarizing the main findings. The suggested alternative scalings of Reynolds and Rossby numbers, using the wingspan as the characteristic length, may be useful in aiding the selection of the optimal aspect ratios for MAVs in the future.

Fluid–structure interaction of a sphere rolling along an inclined plane

Publisher: Cambridge University Press (CUP)

Date: 08-05-2023

DOI: 10.1017/JFM.2023.250

Abstract: A comprehensive investigation, using experimental, computational and analytic methods, is reported on the motion of, and the forces on, spheres of different density ratios rolling freely down an incline in a fluid under gravity. The Reynolds number, based on sphere diameter and terminal velocity, ranged up to 1000 for the experiments, and up to 250 for the computer simulations. A modified Reynolds number, incorporating the density ratio, gravitational acceleration and angle of incline, was found to govern the saturated state of the flow. Transition from steady to unsteady flow was sensitive to mass ratio, with lighter spheres undergoing earlier transition. Indeed, positively buoyant spheres develop cross-slope oscillations prior to the onset of shedding. Also of interest, the transition to chaotic wake flow occurs at Reynolds numbers lower than for a sphere forced to roll at a constant speed. In addition to the average sphere motion, flow-induced vibrations were predicted and measured, with quasi-periodic lateral oscillations found to increase as the flow became more unstable, and to decrease with increased density ratio. The study confirms the time-averaged results of a previous experimental study, although closer inspection shows sensitivity to the relative surface roughness of the sphere and plane in experiments this sensitivity is masked in typical log–log plots of drag against Reynolds number. Physical surface roughness appears to play a role analogous to the necessary imposed gap between the sphere and plane in computations, removing the singularity in drag that would prevent rolling for an incompressible fluid and perfectly smooth surfaces.

Flow characterization of a spinner flask for induced pluripotent stem cell culture application

Publisher: Public Library of Science (PLoS)

Date: 03-10-2014

DOI: 10.1371/JOURNAL.PONE.0106493

Flow-induced vibration of D-section cylinders

Publisher: Cambridge University Press (CUP)

Date: 20-07-2018

DOI: 10.1017/JFM.2018.501

Abstract: While it has been known that an afterbody (i.e. the structural part of a bluff body downstream of the flow separation points) plays an important role affecting the wake characteristics and even may change the nature of the flow-induced vibration (FIV) of a structure, the question of whether an afterbody is essential for the occurrence of one particular common form of FIV, namely vortex-induced vibration (VIV), still remains. This has motivated the present study to experimentally investigate the FIV of an elastically mounted forward- or backward-facing D-section (closed semicircular) cylinder over the reduced velocity range $2.3\\leqslant U^{\\ast }\\leqslant 20$ , where $U^{\\ast }=U/(f_{nw}D)$ . Here, $U$ is the free-stream velocity, $D$ the cylinder diameter and $f_{nw}$ the natural frequency of the system in quiescent fluid (water). The normal orientation with the body’s flat surface facing upstream is known to be subject to another common form of FIV, galloping, while the reverse D-section with the body’s curved surface facing upstream, due to the lack of an afterbody, has previously been reported to be immune to VIV. The fluid–structure system was modelled on a low-friction air-bearing system in conjunction with a recirculating water channel facility to achieve a low mass ratio (defined as the ratio of the total oscillating mass to that of the displaced fluid mass). Interestingly, through a careful overall examination of the dynamic responses, including the vibration litude and frequency, fluid forces and phases, our new findings showed that the D-section exhibits a VIV-dominated response for $U^{\\ast } $ , galloping-dominated response for $U^{\\ast } .5$ , and a transition regime with a VIV–galloping interaction in between. Also observed for the first time were interesting wake modes associated with these response regimes. However, in contrast to previous studies at high Reynolds number (defined by $Re=UD/\\unicode[STIX]{x1D708}$ , with $\\unicode[STIX]{x1D708}$ the kinematic viscosity), which have showed that the D-section was subject to ‘hard’ galloping that required a substantial initial litude to trigger, it was observed in the present study that the D-section can gallop softly from rest. Surprisingly, on the other hand, it was found that the reverse D-section exhibits pure VIV features. Remarkable similarities were observed in a direct comparison with a circular cylinder of the same mass ratio, in terms of the onset $U^{\\ast }$ of significant vibration, the peak litude (only approximately 6 % less than that of the circular cylinder), and also the fluid forces and phases. Of most significance, this study shows that an afterbody is not essential for VIV at low mass and d ing ratios.

Changing profile of couples seeking genetic counseling for consanguinity in Australia

Publisher: Wiley

Date: 22-11-2005

DOI: 10.1002/AJMG.A.30432

Abstract: Consanguineous marriage is rare in most Western countries and, for ex le, in the USA it may be subject to regulation by both civil legislation and religious prescription. This is not the case in many regions of Asia and Africa where marriage within the family is strongly favored. Since the 1970s there has been widespread migration to North America, Western Europe, and Australasia from communities which encourage consanguineous marriage. To assess the effect of this trend on a genetic counseling program, the records of 302 couples referred to Genetic Services of Western Australia for consanguinity counseling were abstracted for the period 1975-2001. Overall, a family history of genetic disease or a previously affected child was reported in 28.8% of cases. Premarital or prepregnancy counseling on grounds of consanguinity was sought by 41.0% of couples, and a further 18.2% of consanguineous couples had been referred because of a consanguineous pregnancy. In 7.6% of cases a relationship closer than first cousin was involved. Through time there was a significant increase in the numbers of consanguineous consultants, and their patterns of religious affiliation and ethnic origin widened markedly. Although effectively excluded from entry to Australia prior to 1975, couples of Asian origin accounted for 25.5% of all consanguineous consultants. With ongoing migration, changes in the ethnic profiles and the specific counseling requirements of consanguineous couples can be expected to continue and probably accelerate.

Resonant sound caused by flow past two plates in tandem in a duct

Publisher: Cambridge University Press (CUP)

Date: 07-1988

DOI: 10.1017/S0022112088001946

Abstract: Two plates placed in tandem in a duct flow shed vortices, which can excite and sustain an acoustic resonance associated with the duct. The sound can in turn ‘feed back’ and ‘lock’ the vortex shedding rate to the sound frequency. The experimental conditions under which loud resonant sound is sustained are described in this paper. The acoustic sources are predicted by combining a vortex model of the flow field with a finite-element solution of the sound field, and then using Howe's theory of aerodynamic sound to calculate the energy exchange between the flow and the sound field. Only in certain regions near the plates is substantial net energy exchange possible the direction of energy transfer depends on the spacing of the plates. The region around the trailing edge of the upstream plate is found to be always a net acoustic source during resonance, while the region around the downstream plate is a net source or sink depending on the phase of the acoustic cycle at which vortices arrive there, which in turn depends on plate spacing and flow velocity. The net source region around the downstream plate is suppressed over a wide range of plate spacings by splitting this plate at midspan and rejoining it so that one half is offset in the flow direction by the distance a vortex travels in half a sound cycle.

Predicting vortex-induced vibration from driven oscillation results

Publisher: Elsevier BV

Date: 10-2006

DOI: 10.1016/J.APM.2005.05.017

Experimental investigation of fluid dynamic instability in a transonic cavity flow

Publisher: Elsevier BV

Date: 02-2007

DOI: 10.1016/J.EXPTHERMFLUSCI.2006.05.007

Wake transition of two-dimensional cylinders and axisymmetric bluff bodies

Publisher: Elsevier BV

Date: 08-2006

DOI: 10.1016/J.JFLUIDSTRUCTS.2006.05.001

Instability of the flow around an impacting sphere

Publisher: Elsevier BV

Date: 08-2006

DOI: 10.1016/J.JFLUIDSTRUCTS.2006.05.002

Computed tomographic x-ray velocimetry

Publisher: AIP

Date: 2010

DOI: 10.1063/1.3478193

Bluff Bodies and Wake–Wall Interactions

Publisher: Annual Reviews

Date: 05-01-2021

DOI: 10.1146/ANNUREV-FLUID-072220-123637

Abstract: This review surveys the dramatic variations in wake structures and flow transitions, in addition to body forces, that appear as the motion of bluff bodies through a fluid occurs increasingly closer to a solid wall. In particular, we discuss the two cases of bluff bodies translating parallel to solid walls at varying heights and bluff bodies impacting on solid walls. In the former case, we highlight the changes to the wake structures as the flow varies from that of an isolated body to that of a body on or very close to the wall, including the effects when the body is rotating. For the latter case of an impacting body, we review the flow structures following impact and their transition to three-dimensionality. We discuss the issue of whether there is solid–solid contact between the bluff body and a wall and its importance to body motion.

Flows past rotating cylinders next to a wall

Publisher: Elsevier BV

Date: 07-2011

DOI: 10.1016/J.JFLUIDSTRUCTS.2011.03.019

A review of rotating cylinder wake transitions

Publisher: Elsevier BV

Date: 02-2015

DOI: 10.1016/J.JFLUIDSTRUCTS.2014.03.010

Hydrodynamics of a particle impact on a wall

Publisher: Elsevier BV

Date: 11-2006

DOI: 10.1016/J.APM.2006.03.014

Smooth particle hydrodynamics simulation of surface coating

Publisher: Elsevier BV

Date: 12-1998

DOI: 10.1016/S0307-904X(98)10040-9

Three-dimensional numerical simulation of blood flow in mouse aortic arch around atherosclerotic plaques

Publisher: Elsevier BV

Date: 09-2014

DOI: 10.1016/J.APM.2014.01.004

Steady inlet flow in stenotic geometries: convective and absolute instabilities

Publisher: Cambridge University Press (CUP)

Date: 10-12-2008

DOI: 10.1017/S0022112008004084

Abstract: Steady inlet flow through a circular tube with an axisymmetric blockage of varying size is studied both numerically and experimentally. The geometry consists of a long, straight tube and a blockage, semicircular in cross-section, serving as a simplified model of an arterial stenosis. The stenosis is characterized by a single parameter, the aim being to highlight fundamental behaviours of constricted flows, in terms of the total blockage. The Reynolds number is varied between 50 and 2500 and the stenosis degree by area between 0.20 and 0.95. Numerically, a spectral-element code is used to obtain the axisymmetric base flow fields, while experimentally, results are obtained for a similar set of geometries, using water as the working fluid. At low Reynolds numbers, the flow is steady and characterized by a jet flow emanating from the contraction, surrounded by an axisymmetric recirculation zone. The effect of a variation in blockage size on the onset and mode of instability is investigated. Linear stability analysis is performed on the simulated axisymmetric base flows, in addition to an analysis of the instability, seemingly convective in nature, observed in the experimental flows. This transition at higher Reynolds numbers to a time-dependent state, characterized by unsteadiness downstream of the blockage, is studied in conjunction with an investigation of the response of steady lower Reynolds number flows to periodic forcing.

Vortex-induced vibration forever even with high structural damping

Publisher: Cambridge University Press (CUP)

Date: 27-04-2023

DOI: 10.1017/JFM.2023.268

Abstract: This study investigates the effect of structural d ing on vortex-induced vibration (VIV) of a circular cylinder when the mass ratio is below its critical value. It is confirmed by water-channel experiments and a reduced-order model (ROM) that the previously identified phenomenon of VIV forever, i.e. resonance oscillations at any reduced velocity, persists even with high structural d ing. Of interest, the ROM results reveal that the wake mode for VIV forever is unstable with a constant positive growth rate with increasing reduced velocity, while the experimental results suggest that VIV forever is associated with a synchronisation between the non-stationary cylinder vibration frequency and the vortex-shedding frequency.

The evolution of a subharmonic mode in a vortex street

Publisher: Cambridge University Press (CUP)

Date: 21-06-2005

DOI: 10.1017/S0022112005004313

Unsteady separation in fluid-structure interaction-I

Publisher: Elsevier BV

Date: 05-2014

DOI: 10.1016/J.JFLUIDSTRUCTS.2014.03.008

Optimization of agitation speed in spinner flask for microcarrier structural integrity and expansion of induced pluripotent stem cells

Publisher: Springer Science and Business Media LLC

Date: 26-07-2016

DOI: 10.1007/S10616-014-9750-Z

Three-dimensionality in the wake of a rapidly rotating cylinder in uniform flow

Publisher: Cambridge University Press (CUP)

Date: 30-07-2013

DOI: 10.1017/JFM.2013.362

Abstract: The flow around an isolated cylinder spinning at high rotation rates in free stream is investigated. The existence of two steady two-dimensional states is confirmed, as is the existence of a secondary mode of vortex shedding. The stability of the two steady states to three-dimensional perturbations is established using linear stability analysis. At lower rotation rates on the first steady state, two three-dimensional modes are confirmed, and their structure and curves of marginal stability as a function of rotation rate and Reynolds number are determined. One mode (named mode $E$ ) appears consistent with a hyperbolic instability in the wake, while the second (named mode $F$ ) appears to be a centrifugal instability of the flow very close to the cylinder surface. At higher rotation rates on the second steady state, a single three-dimensional mode due to centrifugal instability (named mode ${F}^{\\prime } $ ) is found. This mode becomes increasingly difficult to excite as the rotation rate is increased.

Vortex dynamics associated with the collision of a sphere with a wall

Publisher: AIP Publishing

Date: 06-08-2004

DOI: 10.1063/1.1773854

Abstract: For moderate Reynolds numbers, a sphere striking a wall in the normal direction leads to the trailing recirculating wake threading over the sphere and developing into a complex vortex ring system as it interacts with the wall. The primary vortex ring, which consists of vorticity from the wake, persists and convects slowly outwards away from the sphere due to the motion induced from its image. The structure and evolution of this vortex system is quantified through a combined experimental and numerical study. At higher Reynolds numbers a non-axisymmetric instability develops, which leads to rapid dispersion of the ring system. A comparison of the wavelength and growth rate, predicted from both linear stability theory and direct simulations, with idealized models indicates that the mechanism is dominated by a centrifugal instability at the edge of the primary vortex core.

Three-dimensional transition in the wake of bluff elongated cylinders

Publisher: Cambridge University Press (CUP)

Date: 17-08-2005

DOI: 10.1017/S0022112005005082

The sensitivity of steady vortex breakdown bubbles in confined cylinder flows to rotating lid misalignment

Publisher: Cambridge University Press (CUP)

Date: 10-12-2003

DOI: 10.1017/S0022112003006438

Experimental evidence of new three-dimensional modes in the wake of a rotating cylinder

Publisher: Cambridge University Press (CUP)

Date: 14-10-2013

DOI: 10.1017/JFM.2013.486

Abstract: A recent numerical study by Rao et al. ( J. Fluid Mech. , vol. 717, 2013, pp. 1–29) predicted the existence of several previously unobserved linearly unstable three-dimensional modes in the wake of a spinning cylinder in cross-flow. While linear stability analysis suggests that some of these modes exist for relatively limited ranges of Reynolds numbers and rotation rates, this may not be true for fully developed nonlinear wakes. In the current paper, we present the results of water channel experiments on a rotating cylinder in cross-flow, for Reynolds numbers $200\\leqslant \\mathit{Re}\\leqslant 275$ and non-dimensional rotation rates $0\\leqslant \\alpha \\leqslant 2. 5$ . Using particle image velocimetry and digitally post-processed hydrogen bubble flow visualizations, we confirm the existence of the predicted modes for the first time experimentally. For instance, for $\\mathit{Re}= 275$ and a rotation rate of $\\alpha = 1. 7$ , we observe a subharmonic mode, mode C, with a spanwise wavelength of ${\\lambda }_{z} / d\\approx 1. 1$ . On increasing the rotation rate, two modes with a wavelength of ${\\lambda }_{z} / d\\approx 2$ become unstable in rapid succession, termed modes D and E. Mode D grows on a shedding wake, whereas mode E consists of streamwise vortices on an otherwise steady wake. For $\\alpha \\gt 2. 2$ , a short-wavelength mode F appears localized close to the cylinder surface with ${\\lambda }_{z} / d\\approx 0. 5$ , which is presumably a manifestation of centrifugal instability. Unlike the other modes, mode F is a travelling wave with a spanwise frequency of ${\\mathit{St}}_{3D} \\approx 0. 1$ . In addition to these new modes, observations on the one-sided shedding process, known as the ‘second shedding’, are reported for $\\alpha = 5. 1$ . Despite suggestions from the literature, this process seems to be intrinsically three-dimensional. In summary, our experiments confirm the linear predictions by Rao et al. , with very good agreement of wavelengths, symmetries and the phase velocity for the travelling mode. Apart from this, these experiments examine the nonlinear saturated state of these modes and explore how the existence of multiple unstable modes can affect the selected final state. Finally, our results establish that several distinct three-dimensional instabilities exist in a relatively confined area on the $\\mathit{Re}$ – $\\alpha $ parameter map, which could account for their non-detection previously.

Large amplitude cross-stream sphere vibration generated by applied rotational oscillation

Publisher: Elsevier BV

Date: 08-2019

DOI: 10.1016/J.JFLUIDSTRUCTS.2019.03.025

Coupling of vortex shedding with the fundamental resonant mode of a resonator tube

Publisher: Institute of Noise Control Engineering (INCE)

Date: 1993

DOI: 10.3397/1.2827847

The wake behind a cylinder rolling on a wall at varying rotation rates

Publisher: Cambridge University Press (CUP)

Date: 07-04-2010

DOI: 10.1017/S0022112009993053

Abstract: A study investigating the flow around a cylinder rolling or sliding on a wall has been undertaken in two and three dimensions. The cylinder motion is specified from a set of five discrete rotation rates, ranging from prograde through to retrograde rolling. A Reynolds number range of 20–500 is considered. The effects of the nearby wall and the imposed body motion on the wake structure and dominant wake transitions have been determined. Prograde rolling is shown to destabilize the wake flow, while retrograde rotation delays the onset of unsteady flow to Reynolds numbers well above those observed for a cylinder in an unbounded flow. Two-dimensional simulations show the presence of two recirculation zones in the steady wake, the lengths of which increase approximately linearly with the Reynolds number. Values of the lift and drag coefficient are also reported for the steady flow regime. Results from a linear stability analysis show that the wake initially undergoes a regular bifurcation from a steady two-dimensional flow to a steady three-dimensional wake for all rotation rates. The critical Reynolds number Re c of transition and the spanwise wavelength of the dominant mode are shown to be highly dependent on, but smoothly varying with, the rotation rate of the cylinder. Varying the rotation from prograde to retrograde rolling acts to increase the value of Re c and decrease the preferred wavelength. The structure of the fully evolved wake mode is then established through three-dimensional simulations. In fact it is found that at Reynolds numbers only marginally (~5%) above critical, the three-dimensional simulations indicate that the saturated state becomes time dependent, although at least initially, this does not result in a significant change to the mode structure. It is only at higher Reynolds numbers that the wake undergoes a transition to vortex shedding. An analysis of the three-dimensional transition indicates that it is unlikely to be due to a centrifugal instability despite the superficial similarity to the flow over a backward-facing step, for which the transition mechanism has been speculated to be centrifugal. However, the attached elongated recirculation region and distribution of the spanwise perturbation vorticity field, and the similarity of these features with those of the flow through a partially blocked channel, suggest the possibility that the mechanism is elliptic in nature. Some analysis which supports this conjecture is undertaken.

Prediction of vortex shedding from bluff bodies in the presence of a sound field

Publisher: IOP Publishing

Date: 09-1988

DOI: 10.1016/0169-5983(88)90090-1

Volumetric correlation PIV: a new technique for 3D velocity vector field measurement

Publisher: Springer Science and Business Media LLC

Date: 02-2009

DOI: 10.1007/S00348-009-0616-7

Flow past a rotating cylinder translating at different gap heights along a wall

Publisher: Elsevier BV

Date: 08-2015

DOI: 10.1016/J.JFLUIDSTRUCTS.2015.06.015

Spiral streaklines in pre-vortex breakdown regions of axisymmetric swirling flows

Publisher: AIP Publishing

Date: 12-1995

DOI: 10.1063/1.868620

Abstract: In steady swirling flows in closed cylinders, it has been common to observe the transition to spirals of otherwise straight dye streaklines. This occurs in the regions where bubble type breakdown occurs but at a slightly lower Reynolds number. These regions are of particular interest for those seeking to explain the origins of vortex breakdown. The hitherto unexplained occurrence of the spiral streaklines, postulated previously to be due to non-axisymmetry of the flow, is found to be due to small offsets of the dye injection from the central axis. The important implications of this finding are that (i) non-axisymmetry is not a necessary route to bubble-type vortex breakdown, and (ii) that flows displaying spiral streaklines may be still sufficiently axisymmetrical for comparison with numerical and theoretical treatments of the breakdown phenomenon.

Low Reynolds number instabilities and transitions in bluff body wakes

Publisher: IOP Publishing

Date: 04-2007

DOI: 10.1088/1742-6596/64/1/012018

Haemodynamical stress in mouse aortic arch with atherosclerotic plaques: Preliminary study of plaque progression

Publisher: Elsevier BV

Date: 07-2014

DOI: 10.1016/J.CSBJ.2014.07.004

A simple calibration technique for stereoscopic particle image velocimetry

Publisher: Springer Science and Business Media LLC

Date: 28-03-2007

DOI: 10.1007/S00348-007-0293-3

Vortex-induced vibrations of a sphere close to a free surface

Publisher: Cambridge University Press (CUP)

Date: 11-05-2018

DOI: 10.1017/JFM.2018.290

Abstract: Results are presented from an experimental investigation into the effects of proximity to a free surface on vortex-induced vibration (VIV) experienced by fully and semi-submerged spheres that are free to oscillate in the cross-flow direction. The VIV response is studied over a wide range of reduced velocities: $3\\leqslant U^{\\ast }\\leqslant 20$ , covering the mode I, mode II and mode III resonant response branches and corresponding to the Reynolds number range of $5000\\lesssim Re\\lesssim 30\\,000$ . The normalised immersion depth of the sphere is varied in small increments over the range $0\\leqslant h^{\\ast }\\leqslant 1$ for the fully submerged case and $0\\leqslant h^{\\ast }\\leqslant -0.75$ for the semi-submerged case. It is found that for a fully submerged sphere, the vibration litude decreases monotonically and gradually as the immersion ratio is decreased progressively, with a greater influence on the mode II and III parts of the response curve. The synchronisation regime becomes narrower as $h^{\\ast }$ is decreased, with the peak saturation litude occurring at progressively lower reduced velocities. The peak response litude decreases almost linearly over the range of $0.5\\leqslant h^{\\ast }\\leqslant 0.185$ , beyond which the peak response starts increasing almost linearly. The trends in the total phase, $\\unicode[STIX]{x1D719}_{total}$ , and the vortex phase, $\\unicode[STIX]{x1D719}_{vortex}$ , reveal that the mode II response occurs for progressively lower $U^{\\ast }$ values with decreasing $h^{\\ast }$ . On the other hand, when the sphere pierces the free surface, there are two regimes with different characteristic responses. In regime $\\text{I}$ ( $-0.5 h^{\\ast } $ ), the synchronisation region widens and the vibration litude increases, surprisingly becoming even higher than for the fully submerged case in some cases, as $h^{\\ast }$ decreases. However, in regime $\\text{II}$ ( $-0.5\\leqslant h^{\\ast }\\leqslant -0.75$ ), the vibration litude decreases with a decrease in $h^{\\ast }$ , showing a very sharp reduction beyond $h^{\\ast } -0.65$ . The response in regime II is characterised by two distinct peaks in the litude response curve. Careful analysis of the force data and phase information reveals that the two peaks correspond to modes I and II seen for the fully submerged vibration response. This two-peak behaviour is different to the classic VIV response of a sphere under one degree of freedom (1-DOF). The response was found to be insensitive to the Froude number ( $Fr=U/\\sqrt{gD}$ , where $U$ is the free-stream velocity, $D$ is the sphere diameter and $g$ is the acceleration due to gravity) in the current range of $0.05\\leqslant Fr\\leqslant 0.45$ , although higher Froude numbers resulted in slightly lower peak response litudes. The wake measurements in the cross-plane $1.5D$ downstream of the rear of the sphere reveal a reduction in the vorticity of the upper vortex of the trailing vortex pair, presumably through diffusion of vorticity into the free surface. For the piercing sphere case, the near-surface vorticity completely diffuses into the free surface, with only the opposite-signed vortex visible in the cross-plane at this downstream position. Interestingly, this correlates with an even higher oscillation litude than the fully submerged case. Finally, the effects of immersion ratio and diameter ratio ( $D^{\\ast }$ $=$ sphere diameter/support-rod diameter) are quantified, showing care needs to be taken with these factors to avoid unduly influencing VIV predictions.

Uncoupling the effects of aspect ratio, Reynolds number and Rossby number on a rotating insect-wing planform

Publisher: Cambridge University Press (CUP)

Date: 26-11-2019

DOI: 10.1017/JFM.2018.833

Abstract: The in idual and combined influences of aspect ratio ( $A$ ), Reynolds number ( $Re$ ) and Rossby number ( $Ro$ ) on the leading-edge vortex (LEV) of a rotating wing of insect-like planform are investigated numerically. A previous study from our group has determined the wingspan to be an appropriate length scale governing the large-scale LEV structure. In this study, the $A$ range considered is further extended, to show that this scaling works well as $A$ is varied by a factor of 4 ( $1.8\\leqslant A\\leqslant 7.28$ ) and over a $Re$ range of two orders of magnitude. The present study also extends this scaling for wings with an offset from the rotation axis, which is typically the case for actual insects and often for experiments. Remarkably, the optimum range of $A$ based on the lift coefficients at different $Re$ coincides with that observed in nature. The scaling based on the wingspan is extended to the acceleration terms of the Navier–Stokes equations, suggesting a modified scaling of $Ro$ , which decouples the effects of $A$ . A detailed investigation of the flow structures, by increasing $Ro$ in a wide range, reveals the weakening of the LEV due to the reduced spanwise flow, resulting in a reduced lift. Overall, the use of span-based scaling of $Re$ and $Ro$ , together with $A$ , may help reconcile apparent conflicting trends between observed variations in aerodynamic performance in different sets of experiments and simulations.

Numerical and experimental studies of the rolling sphere wake

Publisher: Cambridge University Press (CUP)

Date: 15-01-2010

DOI: 10.1017/S0022112009992072

Abstract: A numerical and experimental investigation is reported for the flow around a rolling sphere when moving adjacent to a plane wall. The dimensionless rotation rate of the sphere is varied from forward to reversed rolling and the resulting wake modes are found to be strongly dependent on the value of this parameter. Results are reported for the Reynolds number range 100 Re 350, which has been shown to capture the unsteady transitions in the wake. Over this range of Reynolds number, both steady and unsteady wake modes are observed. As the sphere undergoes forward rolling, the wake displays similarities to the flow behind an isolated sphere in a free stream. As the Reynolds number of the flow increases, hairpin vortices form and are shed over the surface of the sphere. However, for cases with reversed rotation, the wake takes the form of two distinct streamwise vortices that form around the sides of the body. These streamwise structures in the wake undergo a transition to a new unsteady mode as the Reynolds number increases. During the evolution of this unsteady mode, the streamwise vortices form an out-of-phase spiral pair. Four primary wake modes are identified and a very good qualitative agreement is observed between the numerical and experimental results. The numerical simulations also reveal the existence of an additional unsteady mode that is found to be unstable to small perturbations in the flow.

Computations of the drag coefficients for low-Reynolds-number flow past rings

Publisher: Cambridge University Press (CUP)

Date: 10-03-2005

DOI: 10.1017/S0022112004002836

Damping effect on transverse flow-induced vibration of a rotating circular cylinder and its implied energy harvesting performance

Publisher: American Physical Society (APS)

Date: 17-02-2022

DOI: 10.1103/PHYSREVFLUIDS.7.023905

Three-dimensional transition in the wake of a transversely oscillating cylinder

Publisher: Cambridge University Press (CUP)

Date: 19-04-2007

DOI: 10.1017/S0022112006004320

Abstract: A Floquet stability analysis of the transition to three-dimensionality in the wake of a cylinder forced to oscillate transversely to the free stream has been undertaken. The effect of varying the oscillation litude is determined for a frequency of oscillation close to the natural shedding frequency. The three-dimensional modes that arise are identified, and the effect of the oscillation litude on their structure and growth rate quantified. It is shown that when the two-dimensional wake is in the 2 S configuration (which is similar to the Kármán vortex street), the three-dimensional modes that arise are similar in nature and symmetry structure to the modes in the wake of a fixed cylinder. These modes are known as modes A, B and QP and occur in this order with increasing Re . However, increasing the litude of oscillation causes the critical Reynolds number for mode A to increase significantly, to the point where mode B becomes critical before mode A. The critical wavelength for mode A is also affected by the oscillation, becoming smaller with increasing litude. Elliptic instability theory is shown also to predict this trend, providing further support that mode A primarily arises as a result of an elliptic instability. At higher oscillation litudes, the spatio-temporal symmetry of the two-dimensional wake changes and it takes on the P + S configuration, with a pair of vortices on one side of the wake and a single vortex on the other side, for each oscillation cycle. With the onset of this configuration, modes A, B and QP cease to exist. It is shown that two new three-dimensional modes arise from this base flow, which we call modes SL and SS. Both of these modes are subharmonic, repeating over two base-flow periods. Also, either mode can be the first to become critical, depending on the litude of oscillation of the cylinder. The emergence of these two new modes, as well as the reversal of the order of inception of the three-dimensional modes A and B, leads to the observation that for an oscillating cylinder wake there are four different modes that can lead the transition to three-dimensionality, depending on the litude of oscillation. Therefore this type of flow provides a good ex le for studying the effect of mode-order inception on the path taken to turbulence in bluff-body wakes. For the range of litudes studied, the maximum Re value for which the flow remains two-dimensional is 280.

Flow dynamics and forces associated with a cylinder rolling along a wall

Publisher: AIP Publishing

Date: 11-2006

DOI: 10.1063/1.2375062

Abstract: The wake flow structures and the drag force for a cylinder rolling along a wall without slipping were calculated for the Reynolds number range 20& Re& , covering the two-dimensional shedding regime. Time-dependent numerical computations show the wake undergoes a steady to periodic shedding transition between 85& Re& . The Strouhal number varies only weakly at higher Reynolds number, and is a factor of 3–4 lower than for an isolated rotating or nonrotating body. Also, within this shedding regime, the wake is characterized by counter-rotating vortex pairs, which propagate away from the wall via mutual induction. These pairs are formed as compact vortex structures from the top separating shear layer induce secondary vorticity at the wall, which is pulled up from the boundary to form the semidiscrete flow structures. Over both the steady and unsteady regimes, the (time-mean) recirculation length and drag are quantified.

Flow past a cylinder close to a free surface

Publisher: Cambridge University Press (CUP)

Date: 06-2005

DOI: 10.1017/S0022112005004209

Base pressure coefficients for flows around rectangular plates

Publisher: Elsevier BV

Date: 12-1993

DOI: 10.1016/0167-6105(93)90026-K

Three-dimensional synchrotron x-ray particle image velocimetry

Publisher: AIP Publishing

Date: 15-09-2007

DOI: 10.1063/1.2783978

Abstract: There is great potential to vastly improve biological flow measurement by using a combination of synchrotron imaging and the latest experimental flow measurement techniques. In the current paper, the three-dimensional velocity field within a cylindrical tube is measured using a combination of phase-contrast x-ray imaging and particle image velocimetry (PIV). We greatly refine the techniques previously used to undertake velocity measurements with a synchrotron light source, substantially enhancing accuracy. Furthermore a PIV correlation peak analysis is developed to allow three-dimensional measurement of the velocity field.

Three-dimensionality of elliptical cylinder wakes at low angles of incidence

Publisher: Cambridge University Press (CUP)

Date: 20-07-2017

DOI: 10.1017/JFM.2017.366

Abstract: The wake of an elliptical cylinder at low incident angles is investigated for different aspect ratio ( $\\unicode[STIX]{x1D6E4}=\\text{major:minor axis ratio}$ ) cylinders using stability analysis and direct simulations. In particular, two- and three-dimensional transitions are mapped for cylinders of aspect ratios between 1 and 4 using Floquet stability analysis. The transition scenario for near-unity aspect ratio cylinders resembles that for a circular cylinder wake as Reynolds number is increased to $Re\\lesssim 400$ first, with the transition from steady two-dimensional flow to unsteady two-dimensional flow, followed by the onset of three-dimensional flow via a long-wavelength instability (mode A), then, a short-wavelength instability (mode B) and, finally, an intermediary wavelength instability which is quasi-periodic in nature (mode QP). The effect of the incident angle on this transition scenario for the low-aspect-ratio cylinders is minimal. As the aspect ratio is increased towards 2, two synchronous modes, modes $\\widehat{\\text{A}}$ and $\\widehat{\\text{B}}$ , become unstable these modes have spatio-temporal symmetries similar to their circular cylinder wake counterparts, modes A and mode B, respectively. While mode $\\widehat{\\text{A}}$ persists for all incident angles investigated here, mode $\\widehat{\\text{B}}$ is found only to be unstable for incident angles up to $10^{\\circ }$ . Surprisingly, for $1.8\\lesssim \\unicode[STIX]{x1D6E4}\\lesssim 2.9$ , the mode A instability observed at zero incident angle emerges as a quasi-periodic mode as the incident angle is increased even slightly. At higher incident angles, this quasi-periodic mode once again transforms to a real mode on increasing the Reynolds number. The parameter space maps for the various aspect ratios are presented in the Reynolds number–incident angle plane, and the three-dimensional modes are discussed in terms of similarities to and differences from existing modes. A key aim of the work is to map the different modes and various transition sequences as a simple body geometry is systematically changed and as the flow symmetry is systematically broken thus, insight is provided on the overall path towards fully turbulent flow.

Unsteady separation in fluid–structure interaction—II

Publisher: Elsevier BV

Date: 02-2015

DOI: 10.1016/J.JFLUIDSTRUCTS.2015.01.016

The effect of mass ratio and tether length on the flow around a tethered cylinder

Publisher: Cambridge University Press (CUP)

Date: 30-10-2007

DOI: 10.1017/S002211200700780X

Abstract: A tethered cylinder may be considered an extension of the widely studied problem of a hydro-elastically mounted cylinder. Here we numerically investigate the flow past a positively buoyant tethered cylinder for a range of mass ratios and tether length ratios at a Reynolds number Re = 200. The results are found to be qualitatively similar to related experimental work performed at significantly higher Reynolds numbers. Two important findings are related in this paper. First, we find that the action of the tethered cylinder oscillating at an angle to the flow induces a mean lift coefficient. Second, a critical mass ratio ( m * crit ) is found below which large- litude oscillations are noted, similar to that previously reported for the case of a hydro-elastically mounted cylinder. For short tether lengths, ( m * crit ) is significantly greater than that found for a hydro-elastically mounted cylinder. As the tether length increases, the ( m * crit ) decreases and asymptotes to that of a hydro-elastically mounted cylinder as the tether length approaches infinity.

Chaotic mixing simulations

Publisher: Elsevier BV

Date: 12-1998

DOI: 10.1016/S0307-904X(98)10041-0

California Institute Of Technology

Location: United States of America

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Commonwealth Scientific And Industrial Research Organisation

Location: Australia

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Technical University Of Denmark

Location: Denmark

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Monash University

Location: Australia

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Commonwealth Scientific And Industrial Research Organisation

Location: No location found

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California Institute Of Technology, NASA Jet Propulsion Laboratory

Location: United States of America

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Centre National De La Recherche Scientifique

Location: France

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Measurement And Prediction Of Vulnerable Plaque Formation And Rupture

Start Date: 2011

End Date: 2013

Funder: Australian Research Council

Advanced NanoBiomaterials Imaging Facility

Start Date: 2009

End Date: 2010

Funder: Australian Research Council

Advanced Fluid Mechanics Modelling Of Complex Leukocyte-endothelial Interactions

Start Date: 2008

End Date: 2010

Funder: Australian Research Council

Biomaterials Characterisation Facility

Start Date: 2012

End Date: 2012

Funder: Australian Research Council

Control Of Transitions In Wakes And Swirling Flows

Start Date: 2002

End Date: 2004

Funder: Australian Research Council

Engineering Imaging And Supercomputer Prediction Of Biofluid Flows

Start Date: 2008

End Date: 2011

Funder: Australian Research Council

Structural Reliability Of Engineering Structures In Cyclonic Winds

Start Date: 2020

End Date: 2023

Funder: Australian Research Council

The Mechanisms Determining The Rolling Motions Of Bodies

Start Date: 2020

End Date: 2023

Funder: Australian Research Council

Dynamics And Control Of Fluid-Structure-Free Surface Interactions

Start Date: 2017

End Date: 2019

Funder: Australian Research Council

Fluid Dynamics Of Circulation: Focus On The Kidney

Start Date: 2005

End Date: 2008

Funder: Australian Research Council

Machine Learning And Shape Optimisation Of Fluid-Structure Interactions

Start Date: 2021

End Date: 2023

Funder: Australian Research Council

Dynamics Of Bluff Body Interactions With Walls

Start Date: 2013

End Date: 2016

Funder: Australian Research Council

Phase Contrast X-ray Imaging Of The Lung At Birth

Start Date: 2008

End Date: 2010

Funder: National Health and Medical Research Council

Fluid Mechanics And Physiology Of Blockages In Vascular Systems

Start Date: 2006

End Date: 2007

Funder: Australian Research Council

Strengthening Merit-based Access And Support At The New National Computing Infrastructure Petascale Supercomputing Facility

Start Date: 2012

End Date: 2012

Funder: Australian Research Council

Flow Measurement For Large-scale Industrial Aerodynamics

Start Date: 2017

End Date: 2017

Funder: Australian Research Council

Nanomaterials Optical Characterisation Facility

Start Date: 2007

End Date: 2007

Funder: Australian Research Council

Biomedical Engineering Sensing And Imaging Facility

Start Date: 2006

End Date: 2006

Funder: Australian Research Council

Wake Transitions And Fluid-structure Interactions Of Rotating Bluff Bodies

Start Date: 2015

End Date: 2017

Funder: Australian Research Council

Flow Studies Of Cell Culture Bioreactors

Start Date: 2004

End Date: 2006

Funder: Australian Research Council

Engineering Pore Forming Proteins As Machines For The Delivery Of Proteins And Nanoparticles Into Cells

Start Date: 2010

End Date: 2013

Funder: Australian Research Council

Materials And Surface Characterisation Facility

Start Date: 2005

End Date: 2005

Funder: Australian Research Council

Discovery Projects - Grant ID: DP170100275

Start Date: 06-2017

End Date: 12-2021

Amount: $433,000.00

Funder: Australian Research Council

Discovery Projects - Grant ID: DP0452664

Start Date: 2004

End Date: 09-2007

Amount: $225,000.00

Funder: Australian Research Council

Linkage - International - Grant ID: LX0668992

Start Date: 04-2006

End Date: 12-2007

Amount: $40,000.00

Funder: Australian Research Council

Discovery Projects - Grant ID: DP150102879

Start Date: 2015

End Date: 11-2018

Amount: $613,400.00

Funder: Australian Research Council

Discovery Projects - Grant ID: DP210100990

Start Date: 12-2021

End Date: 12-2024

Amount: $360,000.00

Funder: Australian Research Council

Linkage - International - Grant ID: LX0242362

Start Date: 2002

End Date: 12-2004

Amount: $39,856.00

Funder: Australian Research Council

Super Science Fellowships - Grant ID: FS100100073

Start Date: 2011

End Date: 12-2015

Amount: $835,200.00

Funder: Australian Research Council

Discovery Projects - Grant ID: DP130100822

Start Date: 2013

End Date: 12-2016

Amount: $480,000.00

Funder: Australian Research Council

Discovery Projects - Grant ID: DP0877327

Start Date: 01-2008

End Date: 06-2011

Amount: $350,000.00

Funder: Australian Research Council

Discovery Projects - Grant ID: DP200100704

Start Date: 12-2020

End Date: 06-2024

Amount: $270,000.00

Funder: Australian Research Council

Linkage Projects - Grant ID: LP180100234

Start Date: 10-2020

End Date: 10-2023

Amount: $465,000.00

Funder: Australian Research Council

Discovery Projects - Grant ID: DP0555897

Start Date: 2005

End Date: 04-2008

Amount: $338,000.00

Funder: Australian Research Council

Discovery Projects - Grant ID: DP110100434

Start Date: 2011

End Date: 02-2015

Amount: $460,000.00

Funder: Australian Research Council

Linkage Infrastructure, Equipment And Facilities - Grant ID: LE120100181

Start Date: 03-2012

End Date: 12-2015

Amount: $650,000.00

Funder: Australian Research Council

Linkage Infrastructure, Equipment And Facilities - Grant ID: LE0775612

Start Date: 2007

End Date: 12-2008

Amount: $700,000.00

Funder: Australian Research Council

Linkage Infrastructure, Equipment And Facilities - Grant ID: LE120100131

Start Date: 02-2012

End Date: 02-2013

Amount: $150,000.00

Funder: Australian Research Council

Linkage Infrastructure, Equipment And Facilities - Grant ID: LE0560679

Start Date: 2005

End Date: 12-2005

Amount: $932,870.00

Funder: Australian Research Council

Discovery Projects - Grant ID: DP0877517

Start Date: 01-2008

End Date: 12-2011

Amount: $285,000.00

Funder: Australian Research Council

Linkage Infrastructure, Equipment And Facilities - Grant ID: LE170100203

Start Date: 06-2017

End Date: 12-2020

Amount: $326,000.00

Funder: Australian Research Council

Linkage Infrastructure, Equipment And Facilities - Grant ID: LE0668435

Start Date: 2006

End Date: 03-2007

Amount: $1,300,000.00

Funder: Australian Research Council

Linkage Infrastructure, Equipment And Facilities - Grant ID: LE0989341

Start Date: 10-2009

End Date: 12-2010

Amount: $690,000.00

Funder: Australian Research Council