Hydrodynamic interaction between two spheres

We evaluate the hydrodynamic interaction tensors for two spheres of unequal size and for general mixed slip-stick boundary conditions. A method of reflections leads to a series expansion for the diffusion tensors in powers of the inverse distance l−1 between sphere centers and explicit results are derived through terms of order l−7. It turns out that the series expansion for the diffusion tensors converges much more rapidly than that for the friction tensors.