A Moving Mesh Hydrodynamic Solver for ChaNGa

TL;DR

This paper introduces a moving-mesh hydrodynamics solver integrated into the ChaNGa code, utilizing Voronoi tessellation and advanced gradient estimation to improve accuracy and efficiency in large-scale astrophysical simulations.

Contribution

The paper presents a novel implementation of a moving-mesh hydrodynamics solver in ChaNGa, differing from AREPO, with improved tessellation and gradient methods for better accuracy.

Findings

Validated with standard hydrodynamic tests

Demonstrated in star merger simulations

Showed small differences compared to SPH methods

Abstract

We describe the structure and implementation of a moving-mesh hydrodynamics solver in the large-scale parallel code, Charm N-body GrAvity solver (ChaNGa). While largely based on the algorithm described by Springel (2010) that is implemented in AREPO, our algorithm differs a few aspects. We describe our use of the Voronoi tessellation library, VORO++, to compute the Voronoi tessellation directly. We also incorporate some recent advances in gradient estimation and reconstruction that gives better accuracy in hydrodynamic solutions at minimal computational cost. We validate this module with a small battery of test problems against the smooth particle hydrodynamics solver included in ChaNGa. Finally, we study one example of a scientific problem involving the mergers of two main sequence stars and highlight the small quantitative differences between smooth particle and moving-mesh hydrodynamics. We close with a discussion of anticipated future improvements and advancements.