Enhanced videomicroscopy is being used to observe the intermediate phases formed at the surface of contact between a surfactant solution and oil. With knowledge of equilibrium phase behavior, the results can be interpreted using diffusion theory. Besides providing a basic understanding of interesting phenomena involving simultaneous transport and phase transformation, this work has helped to clarify the basic mechanism of oily soil removal in cold and warm water washing processes. The videomicroscopy system has also been used to observe multiphase flow in a model porous medium and to study the drainage of individual thin liquid films of the type that exist in foams. The latter work and associated modeling, carried out in collaboration with Professor Hirasaki, have provided a quantitative explanation of why there is an abrupt change from fast to slow drainage with increasing surface viscosity of the film.
Slower drainage implies greater foam stability.
This work also involves experiments in sand packs and numerical simulation of the process. Current work emphasizes experiments designed to clarify mechanisms by which gasoline, chlorinated solvents, or other liquid contaminants immiscible with water drain through sand or soil to the wafer table as a result of spills or leaking underground storage tanks. A related research area involves numerical simulation of flow, transport, and chemical reaction including biodegradation in porous media such as ground water aquifers. This work involves collaboration with faculty in the department of computational and applied mathematics and has as its objective development of an improved understanding of processes for cleaning up contaminated aquifers. Bioremediation is one cleanup process that has received considerable attention in recent years.