9318820 Acrivos This project involves the theoretical study of transport processes in two-phase, macroscopically homogenous materials. A variety of analytical and numerical techniques are used to extend the prior work of the P.I.'s on infinitely dilute suspensions to concentrated suspensions and to extend their work on the shear-induced longitudinal and transverse self-diffusivity of particles to the shear-induced gradient diffusivity. This work may lead to fundamental advances in the field of diffusive transport in suspensions because it moves from the basic, simplified, and asymptotic theoretical limiting cases toward the more complex systems in which the potential applications lie. There are many potential applications because of the very fundamental nature of the proposed study. The range of potential applications includes sedimentation, formation of plugs in non-homogeneous shear flow and the re-suspension of settled particles, separation of gas bubbles from liquids under near weightless conditions (production of ultra high purity materials in space) by thermophoresis, and prediction of effective thermal conductivity, permeability, and other transport properties in two-phase media. The effective medium technique for determining the effective properties of composite materials will be put on a firmer theoretical foundation and a kinetic model for computing particle distribution functions in flowing suspensions will be developed. The theoretical studies in this project will be coordinated with the P.I.'s experimental program (funded through U.S. Dept. of Energy) and the data form the literature will be used to test the theoretical results. ***
