Momentum conservation in dissipationless reduced-fluid dynamics

TL;DR

This paper derives a momentum conservation law for dissipationless reduced-fluid models, incorporating polarization, magnetization, and internal torque effects, with an application to gyrofluid toroidal angular momentum in magnetized plasmas.

Contribution

It introduces a variational principle-based derivation of momentum conservation in reduced-fluid models, highlighting polarization, magnetization, and internal torque effects.

Findings

Derived explicit gyrofluid toroidal angular-momentum conservation law.

Identified polarization and magnetization effects in reduced-fluid momentum.

Established a variational framework for dissipationless fluid models.

Abstract

The momentum conservation law for general dissipationless reduced-fluid (e.g., gyrofluid) models is derived by Noether method from a variational principle. The reduced-fluid momentum density and the reduced-fluid canonical momentum-stress tensor both exhibit polarization and magnetization effects as well as an internal torque associated with dynamical reduction. As an application, we derive an explicit gyrofluid toroidal angular-momentum conservation law for axisymmetric toroidal magnetized plasmas.