Abstract:

Suspensions such as corn starch in liquid or superparamagnetic beads used in biomedical assays involve particles several microns or larger in size for which thermal (Brownian) agitation is not significant as the suspensions are sheared. Viscous shear flows, such as pressure-driven flow in a channel, drive these into non-equilibrium states, with nonuniform concentrations and particle stress distributions. Confinement by rigid walls introduces significant local structure to the flow. Methods for the numerical simulation of such flows will be discussed. Results of recent numerical simulations of fully three-dimensional shear flows will be presented for suspensions of spherical particles for dense suspensions over the range of particle volume fractions 20% - 50%. Both the mean structure and the fluctuation levels will be discussed.