Diffusion of a Deformable Body in a random Flow

Abstract

We consider a deformable body immersed in an incompressible liquid that is randomly stirred. Sticking to physical situations in which the body departs only slightly from its spherical shape, we calculate the diffusion constant of the body. We give explicitly the dependence of the diffusion constant on the velocity correlations in the liquid and on the size of the body. We emphasize the particular case in which the random velocity field follows from thermal agitation.