DIFFUSION OF A SPHERE IN HOMOGENEOUS FLOW

We derive the diffusion equation for a sphere immersed in an incompres sible fluid in homogeneous flow, The effect of the finite size of the sphere is taken into account. The generalized Green-Kubo formula and t he Stokes-Einstein relation are derived. As special cases, we analyze the diffusion coefficient for the cases of the simple shear flow and t he pure rotational flow in detail. The relation between nonanalytic de pendence on the velocity gradient and on the frequency is discussed.