ORCID Profile
0000-0002-6069-6105
Current Organisation
University of Newcastle Australia
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Publisher: Springer Science and Business Media LLC
Date: 10-2020
DOI: 10.1007/S10237-019-01230-5
Abstract: Acoustically driven nebulized drug delivery (acoustic aerosol delivery) is the most efficient noninvasive technique for drug delivery to maxillary sinuses (MS). This method is based on the oscillation of the air plug inside the ostium to transport drug particles from the nasal cavity (NC) to the MS. The larger the wavelength of the air plug oscillation in the ostium, the greater the penetration of drug particles to the MS. However, using this technique, the maximum drug delivery efficiency achieved to date is 5%, which means 95% of the aerosolized drugs do not enter the MS and are wasted. Since the largest litude of the air plug oscillation occurs at its resonance frequency, to achieve an improved MS drug delivery efficiency, it is important to determine the resonance frequency of the nose-sinus combination accurately. This paper aims to investigate the impact of geometrical parameters on the resonance frequency of the nose-sinus model. Both experimental and computational acoustic models, along with the theoretical analysis, were conducted to determine the resonance frequency of an idealized nose-sinus model. The computational modeling was carried out using computational fluid dynamics (CFD) and finite element analysis (FEA), whereas in the analytical solution, the mathematical relationships developed for a conventional Helmholtz resonator were employed. A series of experiments were also conducted to measure the resonance frequency of a realistic NC-MS combination. The results demonstrated a good agreement between the experimental and CFD modeling, while the FEA and theoretical analysis showed a significant deviation from the experimental data. Also, it was shown that the resonance frequency of the idealized nose-sinus model increases by up to twofold with increasing the ostium diameter from 3 to 9 mm however, it has an inverse relationship with the ostium length and sinus volume. It was also reported that the resonance frequency of the nose-sinus model is independent of the NC width and MS shape.
Publisher: AIP Publishing
Date: 05-2018
DOI: 10.1063/1.5026130
Abstract: Cavity arrays have been identified as a potential passive device to disrupt and capture sweep events, which are responsible for the excess Reynolds stresses in the boundary layer. In the present study, the mechanism of the attenuation of captured sweep events has been analyzed, as well as the non-linear relationship between the volume of the backing cavity and the reduction in sweep intensity. The influence of cavity array on the turbulent boundary layer has been analyzed, with a total of six different backing cavity arrangements with varying volumes. Three of the backing cavities have been used to determine the non-linear relationship between the effectiveness of the cavity array in reducing sweep intensity and the volume of the backing cavity. The other three have been used to determine the mechanism by which the arrays manipulate the captured sweep events. The pre-multiplied energy spectra of multiple velocity histories were significantly reduced, by up to 12.5%, in the low and mid-range wavelength values (λx+& ), which is associated with the coherent structures. The results show that the maximum reduction in sweep intensity of approximately 7% may be obtained when Reθ = 3771. It has been demonstrated that the non-linear relationship between sweep event intensity reduction and cavity volume has reached an upper limit in this investigation. Results from this study have revealed that the cavity array weakens the sweep intensity of the captured sweep events by d ing the energy of the events through the friction losses in the cavity array and also in the large volume of the backing cavity.
Publisher: Elsevier BV
Date: 06-2017
Publisher: Elsevier BV
Date: 02-2020
Publisher: Elsevier BV
Date: 05-2019
Publisher: Elsevier BV
Date: 11-2019
Publisher: Author(s)
Date: 2016
DOI: 10.1063/1.4949029
Publisher: ASME International
Date: 20-09-2017
DOI: 10.1115/1.4037675
Abstract: In the present study, the optimal two-dimensional (2D) tripping technique for inducing a naturally fully developed turbulent boundary layer in wind tunnels has been investigated. Various tripping techniques were tested, including wires of different diameters and changes in roughness. Experimental measurements were taken on a flat plate in a wind tunnel at a number of locations along the flat plate and at a variety of flow speeds using hot-wire anemometry to measure the boundary layer resulting from each tripping method. The results have demonstrated that to produce a natural turbulent boundary layer using a 2D protuberance, the height of the trip must be less than the undisturbed boundary layer thickness. Using such a trip was shown to reduce the development length of the turbulent boundary layer by approximately 50%. This was shown to hold true for all Reynolds numbers investigated (Rex=1.2×105−1.5×106). The present study provides an insight into the effect of the investigated trip techniques on the induced transition of a laminar boundary layer into turbulence.
Publisher: Cambridge University Press (CUP)
Date: 15-03-2022
DOI: 10.1017/JFM.2022.156
Abstract: The behaviour of a fully rough-wall turbulent boundary layer subjected to different pressure gradients is investigated for different Reynolds numbers using hot-wire measurements. Mean velocity and velocity root-mean-square measurements indicate that the boundary layer remains in a self-preserving state regardless of the pressure gradient. However, different pressure gradients lead to different self-preservation states, as suggested by the lack of collapse of the velocity profile between the pressure gradient cases. The results also indicate that the roughness effect is more important than the pressure gradient particularly, the closer the wall, the more dominant the roughness effect over the pressure gradient effect on the boundary layer. Finally, both spectral and proper orthogonal decomposition analyses applied to the hot-wire measurements indicate that the pressure gradient impacts predominantly the large-scale motion.
Publisher: AIP Publishing
Date: 11-2017
DOI: 10.1063/1.4995466
Abstract: Cavity arrays have been previously identified to disrupt the sweep events and consequently the bursting cycle in the boundary layer by capturing the structures responsible for the Reynolds stresses. In the present study, the sensitivity of a flushed-surface cavity array in reducing the turbulent energy production has been investigated. Two plates of varying thicknesses and four different backing cavity volumes were considered, at three different Reynolds numbers. The volume of the backing cavity was shown to be the most important characteristic in determining the attenuation of streamwise velocity fluctuations within the logarithmic region of the turbulent boundary layer. However, the results also demonstrated that the orifice length of the cavity array had negligible effect in modifying the reduction of the turbulent energy by the cavity array in this investigation. The results show that the maximum reduction in turbulence generation achieved for this study occurs when the backing volume is 3.1 × 106 times greater than the viscous length scale at Reθ = 3771. The reduction in turbulence intensity, sweep intensity, and energy spectrum were shown to be 5.6%, 6.3%, and 13.4%, respectively. By decreasing the cavity volume to zero, no change in the turbulent boundary layer turbulence statistics was found. The results suggest a larger reduction in turbulence intensity, sweep intensity, and energy spectrum that can be achieved with a larger backing volume.
Publisher: Elsevier BV
Date: 04-2018
Publisher: Elsevier BV
Date: 10-2019
Publisher: Springer Science and Business Media LLC
Date: 29-07-2021
Publisher: Springer Science and Business Media LLC
Date: 19-04-2017
Publisher: Cambridge University Press (CUP)
Date: 12-04-2021
DOI: 10.1017/JFM.2021.215
Publisher: AIP Publishing
Date: 2019
DOI: 10.1063/1.5117556
Publisher: AIP Publishing
Date: 2019
DOI: 10.1063/1.5117532
Publisher: Author(s)
Date: 2017
DOI: 10.1063/1.4984497
Publisher: Elsevier BV
Date: 06-2018
Publisher: AIP Publishing
Date: 04-2020
DOI: 10.1063/5.0005594
Abstract: The mean and spectral characteristics of turbulence in the wake flow of a flat plate model resembling a heliostat in the atmospheric boundary layer flow are investigated in a wind tunnel experiment. Mean velocity and turbulence kinetic energy were characterized in the wake of a heliostat model at three elevation angles up to a distance of eight times the characteristic dimension of the heliostat panel. An increase in turbulence intensity and kinetic energy was found in the wake flow, reaching a peak at a distance equal to approximately twice the characteristic dimension of the heliostat panel. Furthermore, spectral and wavelet analysis of velocity fluctuations in the wake showed that the dominant mechanism in the immediate downstream of the plate was the breakdown of large inflow turbulence structures to smaller scales. In the end, the wake-induced turbulence patterns and wind loads in a heliostat field were discussed. It was found that compared to a heliostat at the front row, the heliostats positioned in high-density regions of a field were subjected to a higher turbulence intensity and, consequently, larger dynamic wind loading. The results show that it is necessary to consider the increased unsteady wind loads for the design of a heliostat in high-density regions of a field, where the gap between the rows is less than three-times the characteristic length of the heliostat panel.
Publisher: Informa UK Limited
Date: 02-09-2019
Publisher: Informa UK Limited
Date: 28-05-2014
Publisher: Informa UK Limited
Date: 08-04-2015
Publisher: Author(s)
Date: 2017
DOI: 10.1063/1.4984496
Publisher: Elsevier BV
Date: 11-2017
Publisher: AIP Publishing
Date: 2019
DOI: 10.1063/1.5117571
Publisher: Elsevier BV
Date: 10-2014
Publisher: Elsevier BV
Date: 06-2019
Location: No location found
Location: Iran (Islamic Republic of)
Location: Iran (Islamic Republic of)
Start Date: 2020
End Date: 2023
Funder: Australian Research Council
View Funded Activity