HYDRODYNAMIC FRICTION AND THE CAPACITANCE OF ARBITRARILY-SHAPED OBJECTS

The translational friction coefficient and the capacitance of a variet y of objects are calculated with a probabilistic method involving hitt ing the ''probed'' objects with random walks launched from an enclosin g spherical surface. This method is applied to exactly solvable exampl es to test the program accuracy and to physically important and analyt ically intractable examples (cube, chain of spheres at the vertices of self-avoiding and random walks, etc.). Large fluctuations in the fric tion of polymer chains with a random coil structure are found to give large deviations from the mean-field Kirkwood-Riseman theory and ''hyd rodynamic fluctuation'' effects are found to diminish with the chain s welling accompanying excluded volume interaction. Capacity application s are reviewed and our probabilistic estimates of polymer friction are compared with previous calculations using alternative methods. Transi ents to the capacity and related properties are expressed in terms of fluctuations in the ''Wiener sausage'' volume (volume swept out by a B rownian particle where a repeated visit to a spatial region does not c ontribute to the volume increase in time).