LAUSR

Abstract This paper is the first to evaluate numerically the hydrodynamic forces that apply in two case studies that involve a Newtonian fluid and three in-line spheres (case 1) and a sphere that moves in a circular cell (case 2). The hydrodynamic interactions between the spheres in case 1 or between the central sphere and the surrounding spherical wall in case 2 can be ignored at β (= d f 2 k , where df and k are the diameter and permeability of the sphere, respectively) 50 (solid sphere limit). At 0.5 2, in neither case 1 nor case 2 can a steadily moving system form; in the former case, sweep coagulation-like behavior occurs, and in the latter, zone settling-like behavior occurs.