Range of applicability of modified Fick-Jacobs equation in two dimensions

Abstract

Axial diffusion in a two-dimensional channel of smoothly varying geometry can be approximately described as one-dimensional diffusion in the entropy potential with position-dependent effective diffusivity by means of the modified Fick-Jacobs equation. In this paper, Brownian dynamics simulations are used to study the range of applicability of such a description, as well as the accuracy of the expressions for the effective diffusivity proposed by different researchers.