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TOWARDS LARGE-SCALE SIMULATIONS OF TWO-PHASE FLOWS WITH MOVING CONTACT LINES IN COMPLEX GEOMETRIES

Author
Wang, Sheng
Abstract
Predictive simulation of two-phase flows with moving contact lines is challenging due to their inherent multi-physics and multi-scale nature. Directly simulating such flows incurs an enormous computational cost due to the widely disparate scales at the contact line. Moreover, simulations of viscosity-dominated two-phase flows with moving contact lines are often reported to be mesh-dependent due to the diverging viscous stress at the contact point. This dissertation addresses the above simulation issues and by building a numerical framework to enable large-scale 3D simulations of two-phase flows in complex geometries. By analyzing the weak form of the Navier-Stokes equations for a control volume adjacent to a wall with moving contact line, two unclosed terms are identified: a sub-grid scale (SGS) surface tension force and an SGS viscous force. A closure for the SGS surface tension force is first proposed and tested in a numerical framework for simulating two-phase flows with contact lines. This framework combines a conservative level set method to capture the interface and a conservative cut-cell immersed boundary method to handle complex geometries. Detailed verification tests confirm that simulations using this framework are discretely conservative, accurate, and robust. Secondly, a physics-based closure is derived for the SGS viscous force. Simulations these two SGS models are verified to be mesh-independent and physically accurate across a number of viscosity-dominated two-phase flows, including drop spreading on a horizontal plane and drop sliding down an inclined plane. Finally, the present approach is applied in the study of drop-fiber interactions and jet-wall interactions.
Date Issued
2018-12-30Subject
Fluid Mechanics; Computational physics; Mechanical engineering; fluid structure interaction; liquid-gas flows; moving contact lines
Committee Chair
Desjardins, Olivier
Committee Member
Steen, Paul Herman; Bindel, David S.
Degree Discipline
Mechanical Engineering
Degree Name
Ph. D., Mechanical Engineering
Degree Level
Doctor of Philosophy
Rights
Attribution 4.0 International
Rights URI
Type
dissertation or thesis
Except where otherwise noted, this item's license is described as Attribution 4.0 International