How entropy and hydrodynamics cooperate in rectifying particle transport

TL;DR

This paper investigates how entropy and hydrodynamics work together to control particle transport in asymmetric channels, revealing mechanisms for efficient rectification with reduced diffusion.

Contribution

It combines analytical Fick-Jacobs approximation and simulations to uncover how symmetry breaking and flow induce entropic rectification and trapping.

Findings

Directed particle motion due to bias and flow

Efficient rectification with reduced diffusivity

Mechanisms of entropic trapping in asymmetric channels

Abstract

Using the analytical Fick-Jacobs approximation formalism and extensive Brownian dynamics simulations we study particle transport through two-dimensional periodic channels with triangularly shaped walls. Directed motion is caused by the interplay of constant bias acting along the channel axis and a pressure-driven flow. In particular, we analyze the particle mobility and the effective diffusion coefficient. The mechanisms of entropic rectification is revealed in channels with a broken spatial reflection symmetry in presence of hydrodynamically enforced entropic trapping. Due to the combined action of the forcing and the pressure-driven flow field, efficient rectification with a drastically reduced diffusivity is achieved.