Diffusion in pores and its dependence on boundary conditions

TL;DR

This paper investigates how boundary conditions at the solid-liquid interface affect diffusion in confined fluids, using hydrodynamic modeling and analytical expressions to reveal the impact of partial slip on diffusion coefficients.

Contribution

It provides analytical expressions and numerical estimates showing the significant influence of boundary conditions on particle diffusion near walls.

Findings

Partial slip greatly affects diffusion near walls

Analytical formulas match numerical simulations

Diffusion can probe boundary conditions

Abstract

We study the influence of the boundary conditions at the solid liquid interface on diffusion in a confined fluid. Using an hydrodynamic approach, we compute numerical estimates for the diffusion of a particle confined between two planes. Partial slip is shown to significantly influence the diffusion coefficient near a wall. Analytical expressions are derived in the low and high confinement limits, and are in good agreement with numerical results. These calculations indicate that diffusion of tagged particles could be used as a sensitive probe of the solid-liquid boundary conditions.