INFLUENCE OF HYDRODYNAMIC INTERACTIONS ON SELF-DIFFUSION AND STRESS-RELAXATION IN A SEMIDILUTE SUSPENSION OF HARD-SPHERES

We study the influence of hydrodynamic interactions on the Brownian motion of a semidilute suspension of hard spheres. In particular we consider the time-dependence of the mean square displacement of a selected particle, and the stress relaxation function. In the absence of hydrodynamic interactions and at low density these quantities may be calculated exactly on the basis of the pair Smoluchowski equation. Assuming that in the presence of hydrodynamic interactions the quantities are well approximated by expressions of the same functional form, we evaluate the modification of parameters due to the interactions.