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A computational framework for compressible multiphase flows: application to bubble dynamics, cavitation, and atomization

Bempedelis, Nikolaos; (2020) A computational framework for compressible multiphase flows: application to bubble dynamics, cavitation, and atomization. Doctoral thesis (Ph.D), UCL (University College London).

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Abstract

This thesis presents a computational framework for simulations of compressible multiphase flows, and its application to problems of bubble dynamics, cavitation, and atomization. A novel formulation for ghost fluid methods - concerning the coupling of the flows across material interfaces - is proposed in the first part of the thesis. The formulation is then extended to account for the effects of surface tension. A novel sharp-interface model for unsteady cavitating flows is also developed. The proposed models are implemented in a well-established front tracking framework, allowing for a thorough assessment of their behaviour and accuracy. In the second part of the thesis, the developed framework is used to study two flow problems of significance to fields like cavitation damage, lithotripsy/histotripsy, and liquid fuel injection. The first problem concerns the concentration of energy that occurs in the shock-induced collapse of bubble arrays. The dynamics of certain multi-bubble configurations that have the potential for achieving significant levels of energy focusing are studied for the first time in three dimensions, and their behaviour is shown to be significantly different in comparison to two dimensions. The second problem to be considered concerns the interaction between a gas bubble and a free surface. Focus is on providing insight into the mechanisms of bubble-induced atomization; this is addressed by studying the patterns and dynamics of the liquid jets that are formed at the free surface following its interaction with the bubble.

Type: Thesis (Doctoral)
Qualification: Ph.D
Title: A computational framework for compressible multiphase flows: application to bubble dynamics, cavitation, and atomization
Event: UCL
Language: English
Additional information: Copyright © The Author 2021. Original content in this thesis is licensed under the terms of the Creative Commons Attribution 4.0 International (CC BY 4.0) Licence (https://creativecommons.org/licenses/by/4.0/). Any third-party copyright material present remains the property of its respective owner(s) and is licensed under its existing terms. Access may initially be restricted at the author’s request.
UCL classification: UCL
UCL > Provost and Vice Provost Offices
UCL > Provost and Vice Provost Offices > UCL BEAMS
UCL > Provost and Vice Provost Offices > UCL BEAMS > Faculty of Engineering Science
UCL > Provost and Vice Provost Offices > UCL BEAMS > Faculty of Engineering Science > Dept of Mechanical Engineering
URI: https://discovery.ucl.ac.uk/id/eprint/10118394
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