Dynamical Self-regulation in Self-propelled Particle Flows

TL;DR

This paper presents a combined analytical and numerical study of a continuum model of self-propelled particles, revealing a phase diagram with distinct structures like solitary waves and asters driven by self-regulation and active convection.

Contribution

It introduces a comprehensive phase diagram for self-propelled particle flows, highlighting the roles of self-regulation, active convection, and structure formation, which were not fully understood before.

Findings

Identification of solitary waves and asters as robust structures

Phase diagram mapping different regimes of particle flow

Self-regulation controls phase separation and structure formation

Abstract

We study a continuum model of overdamped self-propelled particles with an aligning interaction in two dimensions. By combining analytical and numerical work, we map out the phase diagram for generic parameters. We find that the system self-organizes into two robust structures in different regions of parameter space: solitary waves of ordered swarms moving through a low density disordered background, and stationary asters. The self-regulating nature of the flow yields phase separation, ubiquitous in this class of systems, and controls the formation of solitary waves. Self-propulsion and the associated active convection play a crucial role in aster formation. A new result of our work is a phase diagram that displays these different regimes in a unified manner.