Speaker: Walter Villanueva, NIST
Title: Diffuse-interface Simulations of Some Capillary-Driven Flows

Abstract: Fluid flows mainly driven by capillary forces will be presented. By means of modeling and simulations, interesting dynamics in some capillary-driven flows can be revealed such as coalescences, breakups, precursor films, flow instabilities, rapid spreading, rigid body motions, and reactive wetting.

Diffuse-interface methods model a fluid interface as having a finite thickness endowed with physical properties such as surface tension. Two diffuse-interface models that are based on the free energy of the system will be presented. The binary model, more specifically the coupled Navier-Stokes/Cahn-Hilliard equations, was used to study different two-phase flows including problems related to microfluidics. The ternary model is developed for more complicated flows such as reactive wetting, where the spreading liquid partially dissolves into the solid substrate. The numerical simulations revealed two stages in the wetting process, a convection-dominated stage where rapid spreading occurs and a diffusion-dominated stage where depression of the liquid-substrate interface and elevation of the contact line region can be observed.

Time: Friday, April 11, 2008, 1:30-2:30 p.m.

Place: Research I, Room 301

Department of Mathematical Sciences
George Mason University
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