Exact hydrodynamics and onset of phase separation for an active exclusion process

TL;DR

This paper derives an exact hydrodynamic model for an active matter lattice system with exclusion, analyzing phase separation onset through stability analysis and simulations, revealing motility-induced phase separation without attractions.

Contribution

It provides the first exact hydrodynamic derivation for an active exclusion process and analyzes phase separation onset.

Findings

Hydrodynamic limit leads to an integro-differential equation for particle density.

Volume exclusion causes nonlinear, density-dependent mobility.

Active matter can undergo phase separation without attractive forces.

Abstract

We consider a lattice model of active matter with exclusion and derive its hydrodynamic description exactly. The hydrodynamic limit leads to an integro-differential equation for the density of particles with a given orientation. Volume exclusion results in nonlinear mobility dependent on spatial density. Such models of active matter can support motility-induced phase separation, which occurs despite the absence of attractive interactions. We study the onset of phase separation with linear stability analysis and numerical simulations.