Hydrodynamic Coupling of Two Brownian Spheres to a Planar Surface
  We describe direct imaging measurements of the collective and relative diffusion of two colloidal spheres near a flat plate. The bounding surface modifies the spheres' dynamics, even at separations of tens of radii. This behavior is captured by a stokeslet analysis of fluid flow driven by the spheres' and wall's no-slip boundary conditions. In particular, this analysis reveals surprising asymmetry in the normal modes for pair diffusion near a flat surface. 
Eric R. Dufresne (1), Todd M. Squires (2), Michael P. Brenner (3),   David G. Grier(1) ((1) University of Chicago, (2) Harva...