The wavelength dependence of the high-frequency shear viscosity in a colloidal suspension of hard spheres

Abstract

Using a lattice-Boltzmann method to simulate the dyanmics of a colloidal suspension of hard spheres, we have calculated the wave-length-dependent viscosity. By extrapolating to small wave vectors we have calculated values for the high-frequency shear viscosity, ν, up to volume fractions of 59%. Where comparison is possible, our values are in good agreement with existing numerical, theoretical and experimental values. Examining the wave-vector-dependent viscosity, ν(k), we find very similar behavior to that found in a much simpler system — the hard sphere fluid. At small k we find that (ν(k) — ν) scales proportionally to k ^3/2 and only for values of the wavevector an order of magnitude smaller than the reciprocal particle radius can the viscosity be considered essentially independent of wave vector.