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Direct numerical simulation of free-surface and interfacial flow using the VOF method: cavitating bubble clouds and phase change
Direct Numerical Simulation of two-phase ow is used extensively for engineering research and fundamental fluid physics studies. This study is based on the Volume-Of-Fluid (VOF) method, originally created by Hirt and Nicols. This method has gained increased popularity, especially when geometric advec...
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| Format: | Thesis |
| Language: | English |
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Department of Mechanical Engineering
2018
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| _version_ | 1867613195518083072 |
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| access_status_str | Open Access |
| author | Malan, Leon |
| author2 | Zaleski, Stéphane |
| author_browse | Malan, Leon Zaleski, Stéphane |
| author_facet | Zaleski, Stéphane Malan, Leon |
| author_sort | Malan, Leon |
| collection | Thesis |
| description | Direct Numerical Simulation of two-phase ow is used extensively for engineering research and fundamental fluid physics studies. This study is based on the Volume-Of-Fluid (VOF) method, originally created by Hirt and Nicols. This method has gained increased popularity, especially when geometric advection techniques are used coupled with a planar reconstruction of the interface. The focus of the first part of this work is to investigate the hydrodynamics of isothermal cavitation in large bubble clouds, which originated from a larger study of micro-spalling, conducted by the French CEA. A method to deal with volume-changing vapour cavities, or pores, was formulated and implemented in an existing code, PARIS. The ow is idealized by assuming an inviscid liquid, negligible thermal effects and vanishing vapour pressure. A novel investigation of bubble cloud interaction in an expanding liquid using Direct or Detailed Numerical Simulation is presented. The simulation results reveal a pore competition, which is characterised by the Weber number in the ow. In the second part of the study the governing equations are extended to describe incompressible ow with phase change. The description of the work commences with the derivation of the governing equations. Following this, a novel, geometric based, VOF solution method is proposed. In this method a novel way of advecting the VOF function is invented, which treats both mass and energy conservation in conservative form. New techniques include the advection of the interface in a discontinuous velocity field. The proposed algorithms are consistent and elegant, requiring minimal modifications to the existing code. Numerical experiments demonstrate accuracy, robustness and generality. This is viewed as a significant fundamental development in the use of VOF methods to model phase change. |
| format | Thesis |
| id | oai:open.uct.ac.za:11427/27898 |
| institution | University of Cape Town (South Africa) |
| language | eng |
| last_indexed | 2026-06-10T12:32:17.361Z |
| license_str | Not specified — see source repository |
| provenance_str_mv | Harvested via OAI-PMH from UCTD — University of Cape Town Open Access Repository |
| publishDate | 2018 |
| publishDateRange | 2018 |
| publishDateSort | 2018 |
| publisher | Department of Mechanical Engineering |
| publisherStr | Department of Mechanical Engineering |
| record_format | dspace |
| source_str | UCTD — University of Cape Town Open Access Repository |
| spelling | oai:open.uct.ac.za:11427/27898 Direct numerical simulation of free-surface and interfacial flow using the VOF method: cavitating bubble clouds and phase change Malan, Leon Zaleski, Stéphane Malan, Arnaud G Rousseau, Pieter G Mechanical Engineering Direct Numerical Simulation of two-phase ow is used extensively for engineering research and fundamental fluid physics studies. This study is based on the Volume-Of-Fluid (VOF) method, originally created by Hirt and Nicols. This method has gained increased popularity, especially when geometric advection techniques are used coupled with a planar reconstruction of the interface. The focus of the first part of this work is to investigate the hydrodynamics of isothermal cavitation in large bubble clouds, which originated from a larger study of micro-spalling, conducted by the French CEA. A method to deal with volume-changing vapour cavities, or pores, was formulated and implemented in an existing code, PARIS. The ow is idealized by assuming an inviscid liquid, negligible thermal effects and vanishing vapour pressure. A novel investigation of bubble cloud interaction in an expanding liquid using Direct or Detailed Numerical Simulation is presented. The simulation results reveal a pore competition, which is characterised by the Weber number in the ow. In the second part of the study the governing equations are extended to describe incompressible ow with phase change. The description of the work commences with the derivation of the governing equations. Following this, a novel, geometric based, VOF solution method is proposed. In this method a novel way of advecting the VOF function is invented, which treats both mass and energy conservation in conservative form. New techniques include the advection of the interface in a discontinuous velocity field. The proposed algorithms are consistent and elegant, requiring minimal modifications to the existing code. Numerical experiments demonstrate accuracy, robustness and generality. This is viewed as a significant fundamental development in the use of VOF methods to model phase change. 2018-05-03T12:28:23Z 2018-05-03T12:28:23Z 2018 Doctoral Thesis Doctoral PhD http://hdl.handle.net/11427/27898 eng application/pdf Department of Mechanical Engineering Faculty of Engineering and the Built Environment University of Cape Town |
| spellingShingle | Mechanical Engineering Malan, Leon Direct numerical simulation of free-surface and interfacial flow using the VOF method: cavitating bubble clouds and phase change |
| thesis_degree_str | Doctoral |
| title | Direct numerical simulation of free-surface and interfacial flow using the VOF method: cavitating bubble clouds and phase change |
| title_full | Direct numerical simulation of free-surface and interfacial flow using the VOF method: cavitating bubble clouds and phase change |
| title_fullStr | Direct numerical simulation of free-surface and interfacial flow using the VOF method: cavitating bubble clouds and phase change |
| title_full_unstemmed | Direct numerical simulation of free-surface and interfacial flow using the VOF method: cavitating bubble clouds and phase change |
| title_short | Direct numerical simulation of free-surface and interfacial flow using the VOF method: cavitating bubble clouds and phase change |
| title_sort | direct numerical simulation of free surface and interfacial flow using the vof method cavitating bubble clouds and phase change |
| topic | Mechanical Engineering |
| url | http://hdl.handle.net/11427/27898 |
| work_keys_str_mv | AT malanleon directnumericalsimulationoffreesurfaceandinterfacialflowusingthevofmethodcavitatingbubblecloudsandphasechange |