Numerical Resistivity and Viscosity:
Abstract:
We propose a simple ansatz for estimating the value of the numerical resistivity and the nu- merical viscosity of any Eulerian magnetohydrodynamics (MHD) code. We test this ansatz with the help of simulations of the propagation of (magneto)sonic waves, Alfven waves, and the tearing mode instability using the MHD code Aenus. By comparing the simulation re- sults with (semi-)analytical solutions of the resistive-viscous MHD equations, we measure the numerical viscosity and resistivity of Aenus. We also determine the dependance of the nu- merical viscosity and resistivity on the Riemman solver, the time integration, and the spatial reconstruction scheme applied in the simulations.
|