Abstract:

We study the effects of hydrodynamic interactions on the diffusion of hard spheres in concentrated suspensions. Using a multiple-light-scattering technique that measures the early-time behavior, we find Deff/D0=1-(1.86±0.07)φ, where φ is the volume fraction of spheres, Deff is the effective diffusion coefficient, and D0 is the free-particle diffusion coefficient. This agrees with the linear φ term calculated theoretically for short-time self-diffusion. The short-time diffusion coefficient is also found to be continuous across the freezing transition.

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