Avalanche Dynamics for Active Matter in Heterogeneous Media

TL;DR

This study uses simulations to explore how active matter disks navigate disordered media, revealing a transition from clogging to flow and intermittent avalanches with power-law size distribution at high activity, akin to jamming and yielding phenomena.

Contribution

It demonstrates that activity induces a nonequilibrium critical state in particulate systems, showing a transition to self-jamming and avalanche dynamics similar to amorphous solids.

Findings

Transition from clogged to flowing states with increasing activity and density

Power-law distributed avalanches with exponent 1.46 at high activity

Self-jamming due to activity-induced clustering

Abstract

Using numerical simulations, we examine the dynamics of active matter run-and-tumble disks moving in a disordered array of obstacles. As a function of increasing active disk density and activity, we find a transition from a completely clogged state to a continuous flowing phase, and in the large activity limit, we observe an intermittent state where the motion occurs in avalanches that are power law distributed in size with an exponent of $\beta = 1.46$. In contrast, in the thermal or low activity limit we find bursts of motion that are not broadly distributed in size. We argue that in the highly active regime, the system reaches a self-jamming state due to the activity-induced self-clustering, and that the intermittent dynamics is similar to that found in the yielding of amorphous solids. Our results show that activity is another route by which particulate systems can be tuned to a nonequilibrium critical state.