Externally driven macroscopic systems: Dynamics versus Thermodynamics

TL;DR

This paper explores the relationship between macroscopic thermodynamics-like modeling and microscopic dynamics in externally driven systems, explaining their indirect connection through reduction from microscopic to mesoscopic descriptions.

Contribution

It clarifies how thermodynamics-like models emerge from microscopic dynamics without explicit potentials, resolving apparent contradictions in mesoscopic system modeling.

Findings

Thermodynamics-like modeling effectively describes driven systems despite lack of explicit potentials.

The relation between dynamic and thermodynamic analyses is indirect, mediated by microscopic reduction.

Understanding this relation improves modeling and prediction of mesoscopic driven systems.

Abstract

Experience collected in mesoscopic dynamic modeling of externally driven systems indicates absence of potentials that could play role of equilibrium or nonequilibrium thermodynamic potentials yet their thermo-dynamics-like modeling is often found to provide a good description, good understanding, and predictions that agree with results of experimental observations. This apparent contradiction is explained by noting that the dynamic and the thermodynamics-like investigations on a given mesoscopic level of description are not directly related. Their relation is indirect. They both represent two aspects of dynamic modeling on a more microscopic level of description. The thermodynamic analysis arises in the investigation of the way the more microscopic dynamics reduces to the mesoscopic dynamics (reducing dynamics) and the mesoscopic dynamic analysis in the investigation of the result of the reduction (reduced dynamics).