Entropy production rate in thermodynamically consistent flocks

Fuente: arXiv
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Auteurs principaux: Agranov, Tal, Jack, Robert L., Cates, Michael E., Fodor, Étienne
Format: Preprint
Publié: 2025
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author Agranov, Tal
Jack, Robert L.
Cates, Michael E.
Fodor, Étienne
author_facet Agranov, Tal
Jack, Robert L.
Cates, Michael E.
Fodor, Étienne
contents We study the entropy production rate (EPR) of aligning self-propelled particles which undergo a flocking transition towards a polarized collective motion. In our thermodynamically consistent lattice model, individual self-propulsion is the exclusive source of irreversibility. We derive the fluctuating hydrodynamics for large system sizes using a controlled coarse-graining: our procedure entails an exact correspondence between the EPR evaluated at the hydrodynamic and particle-based levels. We reveal that EPR is maximal when the system adopts a homogeneous configuration, either apolar or polar, and reduced in the non-homogeneous state where a polar band travels in a apolar background due to strong spatial EPR modulations. By analyzing the latter we also show that asymmetric energetic exchanges occur at the trailing and leading edges, which we map into a thermodynamic cycle in density-polarization space. Finally, we demonstrate that the regime of weak self-propulsion features a singular scaling of EPR, and a non-analyticity of the travelling band profiles.
format Preprint
id arxiv_https___arxiv_org_abs_2505_13117
institution arXiv
publishDate 2025
record_format arxiv
spellingShingle Entropy production rate in thermodynamically consistent flocks
Agranov, Tal
Jack, Robert L.
Cates, Michael E.
Fodor, Étienne
Statistical Mechanics
Soft Condensed Matter
We study the entropy production rate (EPR) of aligning self-propelled particles which undergo a flocking transition towards a polarized collective motion. In our thermodynamically consistent lattice model, individual self-propulsion is the exclusive source of irreversibility. We derive the fluctuating hydrodynamics for large system sizes using a controlled coarse-graining: our procedure entails an exact correspondence between the EPR evaluated at the hydrodynamic and particle-based levels. We reveal that EPR is maximal when the system adopts a homogeneous configuration, either apolar or polar, and reduced in the non-homogeneous state where a polar band travels in a apolar background due to strong spatial EPR modulations. By analyzing the latter we also show that asymmetric energetic exchanges occur at the trailing and leading edges, which we map into a thermodynamic cycle in density-polarization space. Finally, we demonstrate that the regime of weak self-propulsion features a singular scaling of EPR, and a non-analyticity of the travelling band profiles.
title Entropy production rate in thermodynamically consistent flocks
topic Statistical Mechanics
Soft Condensed Matter
url https://arxiv.org/abs/2505.13117