DISCO: A 3D Moving-Mesh Magnetohydrodynamics Code Designed for the Study of Astrophysical Disks

TL;DR

DISCO is a new moving-mesh magnetohydrodynamics code optimized for simulating astrophysical disks, offering improved accuracy and efficiency in modeling orbital fluid dynamics and magnetic phenomena.

Contribution

It introduces a novel constrained transport scheme compatible with a dynamic cylindrical mesh for accurate MHD simulations in astrophysical disks.

Findings

DISCO accurately models the magneto-rotational instability.

The code demonstrates high stability and scalability.

It reduces diffusive advection errors in high Mach number flows.

Abstract

This work presents the publicly available moving-mesh magnetohydrodynamics code DISCO. DISCO is efficient and accurate at evolving orbital fluid motion in two and three dimensions, especially at high Mach number. DISCO employs a moving-mesh approach utilizing a dynamic cylindrical mesh that can shear azimuthally to follow the orbital motion of the gas. The moving mesh removes diffusive advection errors and allows for longer timesteps than a static grid. Magnetohydrodynamics is implemented in DISCO using an HLLD Riemann solver and a novel constrained transport scheme which is compatible with the mesh motion. DISCO is tested against a wide variety of problems, which are designed to test its stability, accuracy and scalability. In addition, several magnetohydrodynamics tests are performed which demonstrate the accuracy and stability of the new constrained transport approach, including two tests of the magneto-rotational instability (MRI); one testing the linear growth rate and the other following the instability into the fully turbulent regime.