A Co-Scaling Grid for Athena++ II: Magnetohydrodynamics

TL;DR

This paper extends a co-scaling formalism to magnetohydrodynamics in Athena++, improving simulation accuracy and efficiency for astrophysical problems involving flow symmetries.

Contribution

It introduces a magnetohydrodynamics extension of the co-scaling formalism in Athena++, compatible with existing methods and validated through standard tests.

Findings

Enhanced simulation accuracy in MHD test cases

Higher computational efficiency compared to fixed-grid methods

Formalism maintains 2nd order spatial accuracy

Abstract

We extend the co-scaling formalism of Habegger & Heitsch (2021) implemented in Athena++ to magneto-hydrodynamics. The formalism relies on flow symmetries in astrophysical problems involving expansion, contraction, and center-of-mass motion. The formalism is fully consistent with the upwind constrained transport method implemented in Athena++ and is accurate to 2nd order in space. Applying our implementation to standard magneto-hydrodynamic test cases leads to improved results and higher efficiency, compared to the fixed-grid solutions.