Active osmotic-like pressure on permeable inclusions

TL;DR

This study investigates how active fluids exert osmotic-like pressure on permeable inclusions with different particle motility inside and outside, revealing pressure differences based on motility and accumulation.

Contribution

It introduces a minimal active Brownian model to analyze pressure effects on permeable inclusions with varying motility, highlighting the influence of system parameters on active pressure.

Findings

Pressure is higher in regions with lower motility due to particle accumulation.

Active pressure depends on membrane hardness and particle density.

Steady-state pressure varies with motility strength and interaction parameters.

Abstract

We use a standard minimal active Brownian model to investigate the osmotic-like effective pressure generated by active fluids on fixed hollow inclusions. These inclusions are enclosed by a permeable (albeit nonflexible) membrane, and the interior and exterior regions of the inclusions have different particle motility strengths. We consider both rectangular and disklike inclusions and analyze the effects of various system parameters, such as excluded volume interaction between active particles, hardness of membrane and active particle density, on the effective pressure produced on the enclosing membrane. We focus on the range of intermediate to high motility strengths and analyze the effective pressure in the steady state. Our findings for the active pressure produced in the interior and exterior regions of the inclusion indicate that the pressure is higher in the region with lower motility due to the relatively stronger accumulation of active particles.