Internal variables and dynamic degrees of freedom

TL;DR

This paper presents a unified framework for dynamic degrees of freedom and internal variables using dual internal variables, deriving evolution equations based on Onsager-Casimir reciprocity.

Contribution

It introduces a dual internal variable concept to unify the treatment of internal variables and dynamic degrees of freedom, with evolution equations depending on reciprocity relations.

Findings

Unified approach to internal variables and dynamic degrees of freedom

Derivation of evolution equations based on reciprocity conditions

Framework applicable to various thermodynamic systems

Abstract

Dynamic degrees of freedom and internal variables are treated in a uniform way. The unification is achieved by means of the introduction of a dual internal variable. This duality provides the corresponding evolution equations depending on whether the Onsager-Casimir reciprocity relations are satisfied or not.