Intrinsic pressure as a convenient mechanical framework for dry active matter

TL;DR

This paper proposes that intrinsic pressure, defined similarly to passive systems, serves as an effective local pressure measure in dry active matter, providing a universal framework for analyzing their mechanics.

Contribution

It introduces a universal mechanical framework based on intrinsic pressure for dry active matter, bridging passive and active system mechanics.

Findings

Intrinsic pressure aligns with local pressure in active systems.

The framework recovers classical mechanical equilibrium in passive systems.

Self-propelling forces act as environmental external forces.

Abstract

The identification of local pressure in active matter systems remains a subject of considerable debate. Through theoretical calculations and extensive simulations of various active systems, we demonstrate that intrinsic pressure (defined in the same way as in passive systems) is an ideal candidate for local pressure of dry active matter, while the self-propelling forces on the active particles are considered as effective external forces originating from the environment. Such a framework is universal and especially convenient for analyzing mechanics of dry active systems, and it recovers the conventional scenario of mechanical equilibrium well-known in passive systems. Thus, our work is of fundamental importance to further explore mechanics and thermodynamics of complex active systems.