Influence of hydrodynamics on many-particle diffusion in 2D colloidal suspensions

摘要

We study many-particle diffusion in 2D colloidal suspensions with full hydrodynamic interactions through a novel mesoscopic simulation technique. We focus on the behaviour of the effective scaled tracer and collective-diffusion coefficients D_T(ρ)/D_0 and D_C(ρ)/D_0 , respectively, where D_0 is the single-particle diffusion coefficient, as a function of the density of the colloids ρ . At low Schmidt numbers S_c ～ 1 , we find that hydrodynamics has essentially no effect on the behaviour of D_T(ρ)/D_0 . At larger S_c, D_T(ρ)/D_0 seems to be enhanced at all densities, although the differences compared to the case without hydrodynamics are rather minor. The collective-diffusion coefficient, on the other hand, is much more strongly coupled to hydrodynamical conservation laws and is distinctly different from the purely dissipative case without hydrodynamic interactions.