256430 Multiphase Flow Phenomena in Chemical and Biological Systems

Sunday, October 28, 2012
Hall B (Convention Center )
Travis W. Walker, Chemical Engineering, Stanford University, Stanford, CA

The addition of multiple phases to flow systems drastically increases the complexity of the flow physics.  These complexities reveal themselves on the macroscopic and microscopic length scales and can involve solids as well as immiscible and miscible fluids.  Interfacial interactions between miscible systems are further complicated by the presence of gradients in the chemical potential that vary in space and time.  These gradients distinguish miscible systems from immiscible systems, which approximate these gradients as discontinuities.  Additional complexities such as the presence of polymers, surfactants, colloids, and particulates to flow systems create complex fluids or soft materials that respond nonlinearly to stress.  A vast number of manufacturing practices involve multphase systems that are highly structured and rheologically complex.

My most recent research activities have focussed on two problems involving flowing, miscible liquids: "rinsing flows," or flows where one liquid is ablated by a second fluid, and the interaction of miscible drops and jets.

The work on rinsing flows was motivated by the desire to remove colloidal, particulate contaminants in the processing of advanced microdevices. Specifically, we investigated the discovery that polymeric liquids could be turned into soft adhesives that effectively eliminate particles without damage to delicate surfaces.

Most recently, I have been investigating the interaction of droplets and jets of a liquid that is miscible with its surroundings. This basic flow problem is central to numerous industrial and natural processes, where mixing of cleansing liquids and creating biocompatible implants for drug delivery are two prominent examples.

The research program that I aim to develop will combine experiment and theory to understand the flow physics of miscible, often non-Newtonian, liquids. A problem of particular interest is mucous transport in the human body, specifically investigating how rheological changes in mucus affect cilia transport in patients with cystic fibrosis.

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