Planet-disc interactions with Discontinuous Galerkin Methods using GPUs

TL;DR

This paper introduces a high-order discontinuous Galerkin method implementation on GPUs for simulating planet-disc interactions, achieving very low numerical viscosity and promising accuracy in complex astrophysical flow scenarios.

Contribution

It develops a GPU-accelerated discontinuous Galerkin code for planet-disc simulations, demonstrating low numerical viscosity and potential advantages over existing methods in complex flows.

Findings

Numerical viscosity as low as 10^{-8}r^2Ω with fifth order schemes.

FARGO3D is faster for simple problems, but DG methods excel in complex flows.

DG methods show promise for accurate, low-viscosity simulations in intricate astrophysical environments.

Abstract

We present a two-dimensional Cartesian code based on high order discontinuous Galerkin methods, implemented to run in parallel over multiple GPUs. A simple planet-disc setup is used to compare the behaviour of our code against the behaviour found using the FARGO3D code with a polar mesh. We make use of the time dependence of the torque exerted by the disc on the planet as a mean to quantify the numerical viscosity of the code. We find that the numerical viscosity of the Keplerian flow can be as low as a few $10^{-8}r^2\Omega$, $r$ and $\Omega$ being respectively the local orbital radius and frequency, for fifth order schemes and resolution of $\sim 10^{-2}r$. Although for a single disc problem a solution of low numerical viscosity can be obtained at lower computational cost with FARGO3D (which is nearly an order of magnitude faster than a fifth order method), discontinuous Galerkin methods appear promising to obtain solutions of low numerical viscosity in more complex situations where the flow cannot be captured on a polar or spherical mesh concentric with the disc.