Research Summary: This research program is aimed at improving current understanding of transport phenomenon of macromolecular solutes in sheared suspensions in the laminar flow regime. Using the novel technique of multiple internal reflection fluorescence (MIRF), augmented mass transfer is characterized by an effective diffusivity and is determined using a rotating disc flow system. The diffusion coefficients of several well characterized macromolecular solutes are measured in aqueous suspensions as a function of suspension particle volume fraction, particle size, particle rigidity, suspension viscosity/viscoelasticity, and system shear rate. Practical Significance: This study could lead to results that improve our current understanding of augmented mass transfer in sheared suspensions by identifying and characterizing the important experimental parameters and mechanisms involved in enhancing the diffusivities of macromolecular solutes in sheared suspensions. Chemical and biological system areas that could benefit include: 1) better understanding of polymer processing operations involving flows with phase change (crystallization, melting, etc.) as well as with dispersed and stratified multiphase flows; 2) better design of nonisothermal tubular and CSTR reactors, packed and fluidized bed reactors, and extracorporeal flow systems such as hemodialyzers and blood oxygenators; and 3) better biomedical understanding of such disease processes as thrombogenesis, atherogenesis, and hemolysis.
