Issue 10, 2023

Boundary design regulates the diffusion of active matter in heterogeneous environments

Abstract

Physical boundaries play a key role in governing the overall transport properties of nearby self-propelled particles. In this work, we develop dispersion theories and conduct Brownian dynamics simulations to predict the coupling between surface accumulation and effective diffusivity of active particles in boundary-rich media. We focus on three models that are well-understood for passive systems: particle transport in (i) an array of fixed volume-excluding obstacles; (ii) a pore with spatially heterogeneous width; and (iii) a tortuous path with kinks and corners. While the impact of these entropic barriers on passive particle transport is well established, we find that these classical models of porous media flows break down due to the unique interplay between activity and the microstructure of the internal geometry. We study the activity-induced slowdown of effective diffusivity by formulating a Smoluchowski description of long-time self diffusivity which contains contributions from the density and fluctuation fields of the active particles. Particle-based and finite element simulations corroborate this perspective and reveal important nonequilibrium considerations of active transport.

Graphical abstract: Boundary design regulates the diffusion of active matter in heterogeneous environments

Supplementary files

Article information

Article type
Paper
Submitted
28 Oct 2022
Accepted
08 Feb 2023
First published
09 Feb 2023

Soft Matter, 2023,19, 1890-1899

Author version available

Boundary design regulates the diffusion of active matter in heterogeneous environments

K. J. Modica, A. K. Omar and S. C. Takatori, Soft Matter, 2023, 19, 1890 DOI: 10.1039/D2SM01421A

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