[논문 리뷰] Thermodynamics of active matter: Tracking dissipation across scales

Robin Bebon, Joshua F. Robinson외 1명|arXiv (Cornell University)|2024. 01. 04.

Advanced Thermodynamics and Statistical Mechanics인용 수 6

한 줄 요약

The paper builds a bottom-up, thermodynamically consistent framework linking explicit solute-driven propulsion to coarse-grained active particle models, deriving exact dissipation expressions across scales.

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.

연구 동기 및 목표

• Motivate a thermodynamically consistent description of active matter across scales from microscopic to macroscopic.
• Connect explicit solute-driven propulsion to effective active Brownian particle models.
• Derive exact expressions for local and global dissipation in coarse-grained hydrodynamic fields.
• Investigate consequences of dissipation for phenomena like wall aggregation and motility-induced phase separation.
• Demonstrate limitations of naive Onsager current formulations in capturing dissipation.

제안 방법

• Introduce a single spherical colloidal particle model with substrate and product solutes and catalytic surface regions.
• Derive force and solute flux expressions from explicit solute densities in a thin interaction layer and a chemostat setup.
• Formulate an effective two-state chemical reaction model with tight coupling to propulsion and derive self-propulsion speed v0 and diffusion Dc^c (Eqs. 9–12).
• Extend to N interacting particles with a detailed stochastic thermodynamics framework for dissipation, including heat rates Qdot^p and Qdot^c (Eqs. 18–21).
• Coarse-grain the model by eliminating the net number of chemical events to obtain a mesoscale ABP description with thermodynamically consistent dissipation (Eq. 28).
• Discuss the linear response regime and applications to confinement and MIPS.

실험 결과

연구 질문

• RQ1 How can one derive thermodynamically consistent dissipation across scales for active matter starting from explicit fuel-solute dynamics?
• RQ2 What are the exact contributions to dissipation from particle motion versus chemical work in active systems?
• RQ3 How does coarse-graining from microscopic solute interactions to active Brownian particles affect the predicted dissipation?
• RQ4 What implications do these dissipation expressions have for phenomena like wall aggregation and motility-induced phase separation?
• RQ5 Where do naive Onsager-type currents fail in capturing local dissipation in active matter?

주요 결과

• A microscopic model with explicit solute molecules yields directed motion with a calculable force and solute flux (Eqs. 2–3).
• An effective chemical-event description yields a self-propulsion speed v0 and a diffusion coefficient Dc^c, with tight coupling between chemical work and displacement (Eqs. 9–12).
• For many interacting particles, a thermodynamically consistent dissipation rate is obtained, partitioned into work from external forces and chemical work (Eq. 18–21).
• Coarse-graining to hydrodynamic fields provides an exact expression for the dissipated heat in terms of density and polarization fields (central result).
• Linear response form can be connected to linear irreversible thermodynamics, and the framework clarifies the thermodynamic footprint of confinement and MIPS.
• Naive Onsager-current approaches can yield incorrect local dissipation, underscoring the need for consistent coarse-graining when tracking dissipation.