ORCID Profile
0000-0002-3727-4174
Current Organisation
Monash University
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Research Topics
In Research Link Australia (RLA), "Research Topics" refer to ANZSRC FOR and SEO codes. These topics are either sourced from ANZSRC FOR and SEO codes listed in researchers' related grants or generated by a large language model (LLM) based on their publications.
Top 5 Research Topics
ANZSRC Field of Research (FoR)
Interdisciplinary Engineering | Turbulent Flows | Interdisciplinary Engineering not elsewhere classified | Computational Fluid Dynamics | Infrastructure Engineering and Asset Management | Fluidisation and Fluid Mechanics |
ANZSRC Socio-Economic Objective (SEO)
Oil and Gas Extraction | Expanding Knowledge in Engineering | Energy Conservation and Efficiency in Transport | Wind Energy | Transport Equipment not elsewhere classified
Related Links
Publications
The effect of tail geometry on the slipstream and unsteady wake structure of high-speed trains
Publisher: Elsevier BV
Date: 05-2017
On the flow past and forces on double-stacked wagons within a freight train under cross-wind
Publisher: Elsevier BV
Date: 11-2020
A field study on the aerodynamics of freight trains
Publisher: Elsevier BV
Date: 02-2021
The nature of the vortical structures in the near wake of the Ahmed body
Publisher: SAGE Publications
Date: 02-2017
Abstract: This study presents the results from high-spatial-resolution water-channel velocity-field measurements behind an Ahmed body with 25° rear slant angle. The Ahmed body represents a simplified generic model of a hatchback automobile that has been widely used to study near-wake flow dynamics. The results help clarify the unresolved question of whether the time-mean near-wake flow structure is topologically equivalent to a toroidal vortex or better described by a pair of horizontally aligned horseshoe vortices, with their legs pointing downstream. The velocimetry data presented allows the tracking of the vortical structures throughout the near wake through a set of orthogonal planes, as well as the measurement of their circulation. The spanwise vortices that form as the flow separates from the top and bottom rear edges are shown to tilt downstream at the sides of the body, while no evidence is found of a time-mean attached toroidal vortex, at least for the Reynolds number (based on the square root of the frontal area) of [Formula: see text] under consideration.
A Comparison of the Wake Structures of Scale and Full-scale Pedalling Cycling Models
Publisher: Elsevier BV
Date: 2016
An Analysis of the Wake of Pedalling Cyclists in a Tandem Formation
Publisher: Elsevier BV
Date: 2016
Siting wind turbines near cliffs: The effect of ruggedness
Publisher: ASME International
Date: 04-10-2019
DOI: 10.1115/1.4041231
Abstract: Wind farms have often been located in close proximity to coastal cliffs to take advantage of the consistent wind regimes associated with many coastal regions, as well as to extract any available increase in flow speed that might be generated by such cliffs. However, coastal cliffs are often rugged as a result of erosion and the natural shape of the landform. This research explores the impact of the three-dimensional cliff topography on the wind flow. Specifically, wind tunnel testing is conducted, modeling the naturally occurring ruggedness as sawtooth lateral variations of various litudes applied to a forward facing step (FFS). Surface shear stress visualization techniques have been employed to derive the flow topology associated with different topographies, while pressure probe measurements are used to measure the development of wind speed and turbulence intensity (TI). Pressure probe measurements and surface pressure taps also assist to determine the lateral and vertical extents of the vortex structures identified. In particular, flow fields characterized by the probe measurements were consistent with vortex bursting that is described by various researchers in the flow over delta wings. Such bursting is observed as a stagnation and corresponding expansion of the vortex. Based on these observations, recommendations are provided for the siting of wind turbines near analogous cliffs.
The influence of reduced Reynolds number on the wake of the DrivAer estate vehicle
Publisher: Elsevier BV
Date: 05-2019
Flow Characteristics of a Three Dimensional Bluff Body With a Single Rotating Cylinder
Publisher: American Society of Mechanical Engineers
Date: 08-07-2012
Abstract: This work investigated the application of a rotating cylinder to the upper leeward edge of a three dimensional bluff body in ground proximity. Aerodynamic drag measurements, base pressure contours and wake velocity profiles were obtained in a closed jet wind tunnel for Reynolds Numbers in the range of approximately 220,000 to 660,000. The cylinder of diameter 0.1H was mounted on the upper edge of the leeward face of the body. The ratio of cylinder surface velocity to freestream velocity was varied from 0 to 2.0. A computational model of the geometry was developed and results are presented for various velocity ratios and cylinder diameters. The results of this work demonstrated that, even at low velocity ratios, the cylinder rotation has a large effect on the flow structures in the body wake region. A large downwash is observed that creates two large counter-rotating vortices and a resultant significant increase in drag. The aerodynamic drag changes are presented as a function of velocity ratio and are shown to be Reynolds Number insensitive over the range tested. Aerodynamic drag was shown to increase with increasing velocity ratio over the velocity ratio range 0.25 to 2.0.
Moving model analysis of the slipstream and wake of a high-speed train
Publisher: Elsevier BV
Date: 2015
Effect of moving ground on the aerodynamics of a generic automotive model: The DrivAer-Estate
Publisher: Elsevier BV
Date: 12-2019
The effect of bogies on high-speed train slipstream and wake
Publisher: Elsevier BV
Date: 11-2018
Flow topology in the wake of a cyclist and its effect on aerodynamic drag
Publisher: Cambridge University Press (CUP)
Date: 28-04-2014
DOI: 10.1017/JFM.2013.678
Abstract: Three-dimensional flows around a full-scale cyclist mannequin were investigated experimentally to explain the large variations in aerodynamic drag that are measured as the legs are positioned around the $360^\\circ $ crank cycle. It is found that the dominant mechanism affecting drag is not the small variation in frontal surface area over the pedal stroke but rather due to large changes in the flow structure over the crank cycle. This is clearly shown by a series of detailed velocity field wake surveys and skin friction flow visualizations. Two characteristic flow regimes are identified, corresponding to symmetrical low-drag and asymmetrical high-drag regimes, in which the primary feature of the wake is shown to be a large trailing streamwise vortex pair, orientated asymmetrically in the centre plane of the mannequin. These primary flow structures in the wake are the dominant mechanism driving the variation in drag throughout the pedal stroke. Topological critical points have been identified on the suction surfaces of the mannequin’s back and are discussed with velocity field measurements to elucidate the time-average flow topologies, showing the primary flow structures of the low- and high-drag flow regimes. The proposed flow topologies are then related to the measured surface pressures acting on the suction surface of the mannequin’s back. These measurements show that most of the variation in drag is due to changes in the pressure distribution acting on the lower back, where the large-scale flow structures having the greatest impact on drag develop.
The double backward-facing step: interaction of multiple separated flow regions
Publisher: Cambridge University Press (CUP)
Date: 15-02-2022
DOI: 10.1017/JFM.2022.9
Abstract: The backward-facing step is perhaps the quintessential geometry used to study separated flow. Extensive previous research has quantified its detailed flow characteristics. However, often regions of separated flow do not exist in isolation rather, interaction occurs between multiple regions. This motivated an experimental investigation into the time-averaged and dynamic flow features of a double backward-facing step, covering separations of zero to eight step heights between equal-height steps. Three flow regimes are identified. A single reattachment regime occurs for separations of less than four step heights, perhaps remarkable for the lack of variation in key flow characteristics from a single backward-facing step response. Next, an intermediate regime is identified for a separation of four step heights. In this case, the flow does not yet reattach on the first step, although significant differences in reattachment length, surface pressure on the vertical step faces and turbulence statistics occur. Finally, for greater step separations, a double reattachment regime, with reattachment on both steps, is identified. Downwash, induced by the first recirculation zone, reduces the reattachment length and turbulent fluctuations of the second recirculation zone. The surface pressure on the first-step vertical face is reduced, seemingly a result of an upstream influence due to the low pressure in the second-step recirculation zone. Detailed characterisation of the regimes offers insight into the fundamental interaction of regions of separated flow, revealing aspects of complex dynamics relevant to a broad range of practical scenarios.
Flow topology of a container train wagon subjected to varying local loading configurations
Publisher: Elsevier BV
Date: 10-2017
Effect of crosswinds and wheel selection on the aerodynamic behavior of a cyclist
Publisher: Elsevier BV
Date: 2012
A Correlation Study of Wind Tunnels for Reduced-Scale Automotive Aerodynamic Development
Publisher: SAE International
Date: 05-04-2016
DOI: 10.4271/2016-01-1598
Aerodynamic test results of bicycle helmets in different configurations: Towards a responsive design
Publisher: SAGE Publications
Date: 12-01-2019
Abstract: Within the sport of cycling, aerodynamic efficiency is a fundamental criterion for equipment such as bicycle frames, wheels, clothing and helmets. Emerging technologies continually challenge the rules governing the sport as designers, engineers, sports scientists and athletes attempt to gain the edge on their competition. This study compares three-dimensional (3D) printed bicycle helmet prototypes with three commercially available helmets via aerodynamic testing in a wind tunnel. One 3D printed helmet featured a mechanical mechanism allowing two states of ventilation closure to be examined for aerodynamic efficiency, while the other featured electronically adjustable ventilation openings tested at five different states of ventilation closure. Data were collected using an anthropometrically accurate mannequin sitting atop a bicycle in a road-cycling position. The results found that the mechanically controlled prototype offered a 4.1% increase in overall drag experienced by the mannequin with ventilation in the open position compared to the closed position. The electronic prototype showed an increase in drag as ventilation openings increased through the five states, with an overall difference in drag of 3.7% between closed and the maximum opening. These experimental findings indicate that the responsive helmet prototypes can significantly affect the drag force on a cyclist between their closed and open positions and, when understood as being adaptable using sensors and automated controls, may provide new opportunities to modify athlete performance throughout varying stages of training and competition.
Dominant flow structures in the wake of a cyclist
Publisher: American Institute of Aeronautics and Astronautics
Date: 25-06-2012
DOI: 10.2514/6.2012-3212
A quasi-static investigation of the effect of leg position on cyclist aerodynamic drag
Publisher: Elsevier BV
Date: 2012
The double backward-facing step: effect of forcing on interacting separated flow regions
Publisher: Cambridge University Press (CUP)
Date: 03-08-2022
DOI: 10.1017/JFM.2022.543
Abstract: This paper demonstrates experimentally that imposed periodic forcing can significantly alter the global flow characteristics of the flow over a double backward-facing step. The geometry consists of two equal height steps spaced up to eight step heights apart. A periodic zero-mass flux jet located at the first step's top corner was issued at frequencies ranging from below the step-mode instability frequency up to approximately five times the shear-layer instability frequency. Reattachment of the flow onto the first step was achieved for step separations as low as three single-step heights with imposed forcing significantly shorter than the five single-step heights that occurred without forcing. A significant reduction in mean base pressure on the first step, and increase on the second step, occurred for low forcing frequencies. Even for large step separations, the effect of forcing on the flow persisted sufficiently far downstream to appreciably influence the development of the second recirculation zone. Importantly, previous forced single and unforced double backward-facing step flows provide reference cases to examine and discuss similarities and differences. This study offers insight into possibilities and potential outcomes of flow control for applications ranging from the drag reduction of ground vehicles such as pickup trucks, to enhanced mixing in industrial processes.
Flow topology and unsteady features of the wake of a generic high-speed train
Publisher: Elsevier BV
Date: 02-2016
The effect of the ground condition on high-speed train slipstream
Publisher: Elsevier BV
Date: 2018
A field study on the aerodynamics of freight trains with different stacking configurations
Publisher: Elsevier BV
Date: 2023
Assessment of various turbulence models (ELES, SAS, URANS and RANS) for predicting the aerodynamics of freight train container wagons
Publisher: Elsevier BV
Date: 11-2017
Computational fluid dynamics study of the effect of leg position on cyclist aerodynamic drag
Publisher: ASME International
Date: 24-07-2014
DOI: 10.1115/1.4027428
Abstract: An experimental and numerical analysis of cycling aerodynamics is presented. The cyclist is modeled experimentally by a mannequin at static crank angle numerically, the cyclist is modeled using a computer aided design (CAD) reproduction of the geometry. Wind tunnel observation of the flow reveals a large variation of drag force and associated downstream flow structure with crank angle at a crank angle of 15 deg, where the two thighs of the rider are aligned, a minimum in drag is observed. At a crank angle of 75 deg, where one leg is at full extension and the other is raised close to the torso, a maximum in drag is observed. Simulation of the flow using computational fluid dynamics (CFD) reproduces the observed variation of drag with crank angle, but underpredicts the experimental drag measurements by approximately 15%, probably at least partially due to simplification of the geometry of the cyclist and bicycle. Inspection of the wake flow for the two sets of results reveals a good match in the downstream flow structure. Numerical simulation also reveals the transient nature of the entire flow field in greater detail. In particular, it shows how the flow separates from the body of the cyclist, which can be related to changes in the overall drag.
A numerical model for the time-dependent wake of a pedalling cyclist
Publisher: SAGE Publications
Date: 09-07-2019
Abstract: A method for computing the wake of a pedalling cyclist is detailed and assessed through comparison with experimental studies. The large-scale time-dependent turbulent flow is simulated using the Scale Adaptive Simulation approach based on the Shear Stress Transport Reynolds-averaged Navier–Stokes model. Importantly, the motion of the legs is modelled by joining the model at the hips and knees and imposing solid body rotation and translation to the lower and upper legs. Rapid distortion of the cyclist geometry during pedalling requires frequent interpolation of the flow solution onto new meshes. The impact of numerical errors, that are inherent to this remeshing technique, on the computed aerodynamic drag force is assessed. The dynamic leg simulation was successful in reproducing the oscillation in the drag force experienced by a rider over the pedalling cycle that results from variations in the large-scale wake flow structure. Aerodynamic drag and streamwise vorticity fields obtained for both static and dynamic leg simulations are compared with similar experimental results across the crank cycle. The new technique presented here for simulating pedalling leg cycling flows offers one pathway for improving the assessment of cycling aerodynamic performance compared to using isolated static leg simulations alone, a practice common in optimising the aerodynamics of cyclists through computational fluid dynamics.
The effect of aspect ratio on the wake of the Ahmed body
Publisher: Springer Science and Business Media LLC
Date: 06-2015
Flow structure between freight train containers with implications for aerodynamic drag
Publisher: Elsevier BV
Date: 05-2019
Characterisation of the wake of the DrivAer estate vehicle
Publisher: Elsevier BV
Date: 06-2018
Wind Tunnel Investigation of a Double Stacked Wagon in Free-Stream
Publisher: American Society of Mechanical Engineers
Date: 26-07-2015
DOI: 10.1115/AJKFLUIDS2015-16508
Abstract: The surface flow structure and pressure distribution of a model representative of a 48ft, double-stacked container wagon of an intermodal freight train is characterized. The model used is 1: 14.6 in scale, and all experiments are conducted in Monash University’s 450kW closed loop wind tunnel. The model employs 474 pressure taps in total, and data is logged with two dynamic pressure-measuring systems. Flow visualizations are carried out on the top and side surfaces using fluorescent Kaolin china clay with kerosene as a carrier. Testing is performed under three different floor boundary-layer profiles in order to assess the sensitivity of the surface flow variation in the floor boundary-layer. It is shown that in a time-averaged sense, the shear-layer separating off the leading edges of the wagon roll up to form three recirculating bubbles on the top and side surfaces. The consequent surface pressure profile matches closely to that of a surface-mounted cube where top and side pressure recovery occurs. For the three boundary-layer profile tested, pressure distribution displays very minor changes. A Karman like left-right wake shedding is observed in the wake with a shedding frequency of St = 0.195.
Contribution of Add-On Components to the Aerodynamic Drag of a Cab-Over Truck-Trailer Combination Vehicle
Publisher: SAE International
Date: 24-09-2013
DOI: 10.4271/2013-01-2428
On the near wake of a simplified heavy vehicle
Publisher: Elsevier BV
Date: 10-2016
The influence of turbulence on cycling aerodynamics
Publisher: Elsevier BV
Date: 11-2023
Optimisation of boat-tails for heavy vehicles
Publisher: ASMEDC
Date: 2011
Abstract: Boat-tails offer significant promise in reducing long haul heavy vehicle aerodynamic drag, and hence fuel consumption and greenhouse gas emissions. This paper presents results from a basic numerical and experimental investigation of drag coefficient reductions for various boat-tail configurations. The vehicle chosen is an arbitrary streamlined front end with a width to height ratio of 64%. No tractor to trailer gap is modeled. Approximate model scale is 12% and test Reynolds Number is ∼850,000. Experimental data and numerical simulations are presented for the zero yaw angle condition. For boat-tail angles where the flow remains largely attached a relationship is observed between drag reduction and the minimum boat-tail area. An optimum boat-tail angle (in the range of 15 degrees) is identified for 0 degrees yaw from both experimental and numerical data. For boat-tail angles greater than optimum a distinct increase in drag is observed in the experimental data, which is associated with flow separation. Comparison of experimental and numerical results show reasonable agreement for attached flow cases, and indicate a similar optimal boat-tail angle.
A wind-tunnel methodology for assessing the slipstream of high-speed trains
Publisher: Elsevier BV
Date: 07-2017
The boundary-layer characteristics and unsteady flow topology of full-scale operational inter-modal freight trains
Publisher: Elsevier BV
Date: 06-2020
Analysis of High Speed Train Flow Structures Under Crosswind
Publisher: American Society of Mechanical Engineers
Date: 26-07-2015
DOI: 10.1115/AJKFLUIDS2015-17796
Abstract: The flow structures along the length of a High-Speed Train (HST) under crosswind are investigated in a wind tunnel, through flow visualisations and velocity measurements at various angles of yaw. Surface visualisations show the development of a streamwise vortex originating at the nose that travels longitudinally along the length of the train. In addition, the hypothesis that flow structures repeat when the boundary layer (BL) on the roof of the HST model is pushed off is tested, with a view to analysing the effectiveness of using shortened HST models to accurately represent full-length trains in a wind tunnel. It would appear that using a shortened train model cannot completely model full-scale HSTs at realistic yaw angles using this theory.
Dynamic leg-motion and its effect on the aerodynamic performance of cyclists
Publisher: Elsevier BV
Date: 08-2016
An experimental characterisation of the wake of a detailed heavy vehicle in cross-wind
Publisher: Elsevier BV
Date: 04-2018
Riding against the wind: a review of competition cycling aerodynamics
Publisher: Springer Science and Business Media LLC
Date: 04-05-2017
Dynamics of trailing vortices in the wake of a generic high-speed train
Publisher: Elsevier BV
Date: 08-2016
Wind tunnel analysis of the slipstream and wake of a high-speed train
Publisher: Elsevier BV
Date: 11-2014
The effect of spatial position on the aerodynamic interactions between cyclists
Publisher: Elsevier BV
Date: 2014
A wind-tunnel case study: Increasing road cycling velocity by adopting an aerodynamically improved sprint position
Publisher: SAGE Publications
Date: 08-2019
Abstract: The main aim of this study was to evaluate the potential to reduce the aerodynamic drag by studying road sprint cyclists’ positions. A male and a female professional road cyclist participated in this wind-tunnel study. Aerodynamic drag measurements are presented for a total of five out-of-seat sprinting positions for each of the athletes under representative competition conditions. The largest reduction in aerodynamic drag measured for each athlete relative to their standard sprinting positions varied between 17% and 27%. The majority of this reduction in aerodynamic drag could be accounted for by changes in the athlete’s projected frontal area. The largest variation in repeat drag coefficient area measurements of out-of-seat sprint positions was 5%, significantly higher than the typical .5% observed for repeated testing of time-trial cycling positions. The majority of variation in repeated drag coefficient area measurements was attributed to reproducibility of position and s ling errors associated with time-averaged force measurements of large fluctuating forces.
Flow field interactions between two tandem cyclists
Publisher: Springer Science and Business Media LLC
Date: 19-11-2016
Aerodynamic performance and riding posture in road cycling and triathlon
Publisher: SAGE Publications
Date: 19-09-2015
Abstract: Cycling performance is strongly dependent on aerodynamic drag, of which the majority is attributable to the rider. Previous studies have shown the importance of optimising athlete posture on the bicycle for in idual time-trial events. This article identifies that performance in road cycling and draft-legal triathlon can be improved through aerodynamic optimisation of the athlete’s posture. Nine relevant cycling postures have been studied, and it was found that for road cycling, gripping the hoods with horizontal forearms can reduce the required cyclist power by 13.4%, and for draft-legal triathlon applications, the use of short bar extensions reduced the required power by up to 16.7%. It was also found that lowering the eyes and head increased drag in both drops and triathlon postures. Measurements of the velocity profiles of the wake of a cyclist in four different postures are presented, and it is shown that differences in drag coefficients between postures can be correlated with changes in the wake velocity defect and turbulence intensity distribution.
Surface flow visualisation over forward facing steps with varying yaw angle
Publisher: IOP Publishing
Date: 16-12-2014
Numerical and Experimental Investigation of the Effect of Multiple Rotating Cylinders on Base Pressure of a Three Dimensional Bluff Body in Ground Proximity
Publisher: American Institute of Aeronautics and Astronautics
Date: 25-06-2012
DOI: 10.2514/6.2012-2656
Aerodynamic drag interactions between cyclists in a team pursuit
Publisher: Springer Science and Business Media LLC
Date: 11-02-2015
Development of a Wind Tunnel Test Section for Evaluation of Heavy Vehicle Aerodynamic Drag at a scale of 1:3
Publisher: SAE International
Date: 24-09-2013
DOI: 10.4271/2013-01-2455
The performance of different turbulence models (URANS, SAS and DES) for predicting high-speed train slipstream
Publisher: Elsevier BV
Date: 06-2017
Analysis of high-speed train flow structures under crosswind
Publisher: Springer Science and Business Media LLC
Date: 09-2016
Siting wind turbines near cliffs—the effect of wind direction
Publisher: Wiley
Date: 30-09-2016
DOI: 10.1002/WE.1931
Related Organisations
Related Funding Activities
Linkage Projects - Grant ID: LP180100234
Start Date: 10-2020
End Date: 10-2023
Amount: $465,000.00
Funder: Australian Research Council
View Funded ActivityLinkage Infrastructure, Equipment And Facilities - Grant ID: LE170100203
Start Date: 06-2017
End Date: 12-2020
Amount: $326,000.00
Funder: Australian Research Council
View Funded Activity