Thermodynamics of active matter: Tracking dissipation across scales

TL;DR

This paper investigates how local dissipation in active matter systems manifests on large scales, providing a detailed thermodynamic analysis from microscopic models to hydrodynamic equations, and highlighting the importance of accurate dissipation calculations.

Contribution

It offers a rigorous derivation of entropy production in active matter, connecting microscopic models to hydrodynamic descriptions and correcting common misconceptions about dissipation.

Findings

Derived explicit expressions for entropy production in active particles.

Showed how active Brownian particle models emerge from microscopic dynamics.

Identified inaccuracies in naive Onsager current applications for dissipation.

Abstract

The concept of entropy has been pivotal in the formulation of thermodynamics. For systems driven away from thermal equilibrium, a comparable role is played by entropy production and dissipation. Here we provide a comprehensive picture how local dissipation due to effective chemical events manifests on large scales in active matter. We start from a microscopic model for a single catalytic particle involving explicit solute molecules and show that it undergoes directed motion. Leveraging stochastic thermodynamics, we calculate the average entropy production rate for interacting particles. We then show how the model of active Brownian particles emerges in a certain limit and we determine the entropy production rate on the level of the hydrodynamic equations. Our results augment the model of active Brownian particles with rigorous expressions for the dissipation that cannot be inferred from their equations of motion, and we illustrate consequences for wall aggregation and motility-induced phase separation. Notably, our bottom-up approach reveals that a naive application of the Onsager currents yields an incorrect expression for the local dissipation.