Brownian dynamics simulations of self and collective diffusion of near hard sphere colloidal liquids: inclusion of many-body hydrodynamics

摘要

Ermak's 1975 Brownian dynamics free-draining algorithm is extended to include the coarse grained effects of many-body hydrodynamics, using a local density approximation for the friction coefficient. The model reproduces the long term self-diffusion coefficients of model near hard sphere colloidal liquids within the experimental uncertainty over the complete solid volume fraction range. The local structural relaxation, manifested in the force autocorrelation functions, is slowed down upon the introduction of mean-field hydrodynamics. This effect is also evident in the collective diffusion coefficients, which show an enhanced relative slowing down compared with the free-draining model at wavevectors k ～ 2π/σ.