Towards a geometric variational discretization of compressible fluids: the rotating shallow water equations

TL;DR

This paper develops a geometric variational discretization scheme for compressible fluids, extending previous incompressible models to the compressible case, and evaluates its performance on rotating shallow water equations.

Contribution

It introduces a structure-preserving discretization framework for compressible fluids on irregular meshes, extending prior work on incompressible fluids.

Findings

Scheme conserves mass and energy

Accurately models nonlinear dynamics

Preserves stationary solutions

Abstract

This paper presents a geometric variational discretization of compressible fluid dynamics. The numerical scheme is obtained by discretizing, in a structure preserving way, the Lie group formulation of fluid dynamics on diffeomorphism groups and the associated variational principles. Our framework applies to irregular mesh discretizations in 2D and 3D. It systematically extends work previously made for incompressible fluids to the compressible case. We consider in detail the numerical scheme on 2D irregular simplicial meshes and evaluate the scheme numerically for the rotating shallow water equations. In particular, we investigate whether the scheme conserves stationary solutions, represents well the nonlinear dynamics, and approximates well the frequency relations of the continuous equations, while preserving conservation laws such as mass and total energy.