Scaling in multi-phase flow
Abstract
Multi-phase, free surface flows encompass a great deal of today's industrial applications and many ubiquitous phenomena encountered in daily life. Separation processes, bubbling and foam production, emulsification, immunoisolation of pancreatic islet cells, capillary blood flow, coalescence and breakup of falling raindrops, just to name a few. The primary goal of this thesis is to advance the understanding of complex multi-phase systems, including characterizing the physics of bubble pinch-off and developing mechanisms that describe the conditions under which entrainment occurs in selective withdrawal. In selective withdrawal, fluid is withdrawn through a tube that has its tip suspended a distance S above a flat interface separating two fluids. When the withdrawal rate Q is low, the interface forms a steady-state hump and only the upper fluid is withdrawn. When Q is increased (or S decreased), the interface undergoes a topological transition so that the lower fluid is entrained with the upper one, forming a steady-state spout. Here, this discontinuous transition is analyzed computationally when both fluids are incompressible and Newtonian. The numerical method employed is an implicit method of lines ALE algorithm which uses Galerkin finite-elements (G/FEM) with elliptic mesh generation. Considering now, the case when air is entrained in an external fluid, e.g., in flow-focusing or air emulsification, the air jet will eventually break due to capillarity, forming bubbles. A separate G/FEM algorithm is developed to study the pinch-off dynamics of a compound jet whose core is air surrounded by a viscous external fluid.
Degree
Ph.D.
Advisors
Harris, Purdue University.
Subject Area
Chemical engineering
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