Self-propulsion and self-navigation: Activity is a precursor to jamming

TL;DR

This paper demonstrates that activity and target accumulation in self-propelled particles can lead to jamming, with motility-induced phase separation acting as a precursor, and provides insights into delaying or preventing jams.

Contribution

It reveals how target-driven activity causes jamming through phase separation, offering a quantitative prediction of jamming onset and strategies to mitigate it.

Findings

Jams emerge from motility-induced phase separation.

Target accumulation triggers an additional instability leading to jams.

Transport efficiency peaks near the jamming transition.

Abstract

Traffic jams are an everyday hindrance to transport, and typically arise when many vehicles have the same or a similar destination. We show, however, that even when uniformly distributed in space and uncorrelated, targets have a crucial effect on transport. At modest densities an instability arises leading to jams with emergent correlations between the targets. By considering limiting cases of the dynamics which map onto active Brownian particles, we argue that motility induced phase separation is the precursor to jams. That is, jams are MIPS seeds that undergo an extra instability due to target accumulation. This provides a quantitative prediction of the onset density for jamming, and suggests how jamming might be delayed or prevented. We study the transition between jammed and flowing phase, and find that transport is most efficient on the cusp of jamming.