Molecular dynamics simulation of hindered diffusion in microcapillaries

Abstract

A general model for diffusion in membranes is employed to illustrate that the individual contributions of diffusion relative to the membrane and self-diffusion in the pore fluid are simply related to the autocorrelation function for the instantaneous centre of mass velocity of the pore fluid and the usual autocorrelation function for the particle velocities. These results are used to analyse molecular dynamics simulation data for hindered diffusion of rigid sphere fluids in cylindrical pores over a wide range of pore fluid densities and pore sizes. Two reflection conditions, specular and diffuse scattering from the pore wall, are also investigated. The results obtained for diffuse scattering are in qualitative agreement with experimental data reported in the literature. These results also suggest that dense fluids and liquids may undergo a small, nonzero degree of slip during flow past a rigid boundary.