Giant enhancement of hydrodynamically enforced entropic trapping in thin channels

TL;DR

This study combines a generalized Fick-Jacobs approach and Brownian dynamics simulations to reveal a significant suppression of particle diffusivity in thin, periodically structured channels under combined bias and flow conditions.

Contribution

It introduces a comprehensive analysis of particle transport in 3D channels, highlighting the dramatic diffusivity reduction in thin channels due to flow profile changes.

Findings

Effective diffusivity is suppressed by four orders of magnitude in thin channels.

Flow profile shape critically influences particle velocity and diffusion.

Transport behavior depends strongly on channel height and flow conditions.

Abstract

Using our generalized Fick-Jacobs approach [Martens et al., PRL 110, 010601 (2013); Martens et al., Eur. Phys. J. Spec. Topics 222, 2453-2463 (2013)] and extensive Brownian dynamics simulations, we study particle transport through three-dimensional periodic channels of different height. Directed motion is caused by the interplay of constant bias acting along the channel axis and a pressure-driven flow. The tremendous change of the flow profile shape in channel direction with the channel height is reflected in a crucial dependence of the mean particle velocity and the effective diffusion coefficient on the channel height. In particular, we observe a giant suppression of the effective diffusivity in thin channels; four orders of magnitude compared to the bulk value.