Simulation of hindered settling in bidisperse suspensions of rigid spheres

We use a recently developed algorithm to simulate and study the physics of bidisperse suspensions of rigid spheres. We compute the settling velocity a s a function of the ratio lambda equivalent to a(L)/a(S) greater than or eq ual to 1 of the radius of the large a(L) and small a(S) particles at a soli d volume fraction of phi = 0.14 and compare our results to predictions of t he theory by Batchelor and a semi-analytical formula by Davis and Gecol. No ne of these predictions agree well with our findings, but the Davis and Gec ol form seems to capture some aspects of the physics in the semi-dilute reg ime more accurately. (C) 1999 Elsevier Science B.V. All rights reserved.