Hydronamic Coupling of Two Brownian Spheres

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Reference

Eric R. Dufresne, Todd M. Squires, Michael P. Brenner, and David G. Grier, "Hydrodynamic Coupling of Two Brownian Spheres to a Planar Surface", Physical Review Letters 2000 85(15), 3317-3320

Introduction

This paper describes direct imaging measurements of the collective and relative diffusion of two colloidal spheres near a flat plate. The bounding surface modifies the spheres' dynamics and this behavior is captured by a stokeslet analysis of fluid flow driven by the spheres' and wall's no-slip boundary conditions. This reveals surprising asymmetry in the normal modes for pair diffusion near a flat surface.

Results

Discussion

Confining surface can influence colloidal dynamics even at large separations, and that this three-surface coupling is accurately described by a leading-order stokeslet approximation. This results suggest that the same formalism can be applied to more general configurations of spheres and bounding surfaces. Wall-induced hydrodynamic interactions may influenced nonequilibrium optical tweezer measurements of confined colloidal interactions and may have contributed to the observed attractions between like-charged spheres.