ORCID Profile
0000-0002-4294-729X
Current Organisation
Faculty of Engineering, University of Sydney
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Publisher: Elsevier BV
Date: 11-2022
DOI: 10.1016/J.IJPHARM.2022.122219
Abstract: This study aims to systematically isolate different anatomical features of the human pharynx with the goal to investigate their independent influence on airflow dynamics and particle deposition characteristics in a geometrically realistic human airway. Specifically, the effects of the uvula, epiglottis and soft palate on drug particle deposition are studied systematically, by carefully removing each of these anatomical features from reconstructed models based on MRI data and comparing them to a benchmark realistic airway model. Computational Fluid Dynamics using established turbulence models is employed to simulate the transport of mono-dispersed particles (3 µm) in the airway at two flow-rates. The simulations suggest three findings: 1) widening the space between the oral cavity and oropharynx and where the soft palate is situated leads to the most dramatic reduction in drug deposition in the upper airway 2) exclusion of the uvula and epiglottis: a) affects flow dynamics in the airway b) alters regional deposition behaviour c) does not significantly affect the total number of particles deposited in the pharynx and 3) the space adjacent to the soft palate is a key determinant for aerosol deposition in the extrathoracic region and is related to mechanisms of flow acceleration, ersion and recirculation.
Publisher: Cambridge University Press (CUP)
Date: 25-01-2021
Publisher: Cambridge University Press (CUP)
Date: 29-12-2021
DOI: 10.1017/JFM.2020.921
Publisher: Elsevier BV
Date: 04-2020
Publisher: Informa UK Limited
Date: 12-09-2019
Publisher: Elsevier BV
Date: 11-2023
Publisher: Cambridge University Press (CUP)
Date: 30-01-2023
DOI: 10.1017/JFM.2023.20
Abstract: The present study investigates the profiles of statistically axisymmetric turbulent jets with arbitrary buoyancy. Analytical expressions for the shape of the radial velocity, Reynolds stress and radial scalar flux profiles are derived from the governing equations by assuming self-similar Gaussian mean velocity and scalar profiles. Previously these have only been derived for the special cases of pure jets and plumes, whereas the present study generalises them to arbitrary buoyancies. These are then used to derive analytical expressions for the turbulent Schmidt/Prandtl numbers, which, along with the mean profiles, are shown to give predictions in agreement with existing literature.
Publisher: Cambridge University Press (CUP)
Date: 31-03-2022
DOI: 10.1017/JFM.2022.152
Abstract: Turbulent fountain flow consists of two distinct stages, the initial ‘negatively buoyant jet’ (NBJ) stage, and the fully developed ‘fountain’ stage. The present study investigates both stages of the flow using particle image velocimetry and planar laser-induced fluorescence, over a range of source Froude numbers, $10\\lesssim Fr_o\\lesssim 30$ , and Reynolds numbers, $5500\\lesssim Re_o\\lesssim 7700$ . While the velocity and buoyancy profiles in NBJs take similar Gaussian shapes over a wide range of axial locations, this was not observed in fountains. The changing profile shape is most evident in the outer flow (OF) region, while there is a degree of similarity in the inner flow (IF). Entrainment between IF and OF is shown to depend on the local Richardson number, $Ri$ . The fountains are found to have a negative entrainment coefficient, $\\alpha $ , for the majority of their height, implying a net radial outflow of fluid from the IF to the OF. An alternative description of entrainment is considered, the ‘decomposed top-hat’ model, where the radial flow is separated into inflow and outflow components that are then estimated using the present experimental data. The inflow component was found to be proportional to the axial IF velocity, which is similar to the classical description of entrainment in pure jets lumes, while the outflow depends on the local $Ri$ . Entrainment in NBJs may also be described by this framework, which, despite not having an OF, is still subject to an $Ri$ -dependent radial outflow.
Location: No location found
No related grants have been discovered for Liam Milton-McGurk.