Magnetohydrodynamics on an unstructured moving grid
Abstract
Magnetic fields play an important role in astrophysics on a wide variety of scales, ranging from the Sun and compact objects to galaxies and galaxy clusters. Here we discuss a novel implementation of ideal magnetohydrodynamics (MHD) in the movingmesh code AREPO which combines many of the advantages of Eulerian and Lagrangian methods in a single computational technique. The employed grid is defined as the Voronoi tessellation of a set of meshgenerating points which can move along with the flow, yielding an automatic adaptivity of the mesh and a substantial reduction of advection errors. Our scheme solves the MHD Riemann problem in the rest frame of the Voronoi interfaces using the HLLD Riemann solver. To satisfy the divergence constraint of the magnetic field in multiple dimensions, the Dedner divergence cleaning method is applied. In a set of standard test problems, we show that the new code produces accurate results and that the divergence of the magnetic field is kept sufficiently small to closely preserve the correct physical solution. We also apply the code to two first application problems, namely supersonic MHD turbulence and the spherical collapse of a magnetized cloud. We verify that the code is able to handle both problems well, demonstrating the applicability of this MHD version of AREPO to a wide range of problems in astrophysics.
 Publication:

Monthly Notices of the Royal Astronomical Society
 Pub Date:
 December 2011
 DOI:
 10.1111/j.13652966.2011.19591.x
 arXiv:
 arXiv:1108.1792
 Bibcode:
 2011MNRAS.418.1392P
 Keywords:

 MHD;
 turbulence;
 methods: numerical;
 stars: formation;
 Astrophysics  Instrumentation and Methods for Astrophysics
 EPrint:
 11 pages, 9 figures, accepted by MNRAS