Trapping of finite-sized Brownian particles in porous media

It is shown that the trapping of finite-sized spherical Brownian particles of radius βR in a system of interpenetrable spherical traps of radius R is isomorphic to the trapping of "point" Brownian particles (β=0) in a particular system of interpenetrable spherical traps of radius (1+β)R. This isomorphism in conjunction with previous trapping-rate data for β=0 is employed to compute the trapping rate for the case β=1/4 in a system of hard spherical traps as a function of trap volume fraction. The effect of increasing the size of the Brownian particles is to increase the trapping rate relative to the instance of point Brownian particles.