New relaxation solvers for Hydro- and Magnetohydrodynamics applied to astrophysical turbulence simulations

C. Klingenberg, University of Würzburg, Germany

Wednesday, November 18
at 16.15, HG E 1.1

We present a relaxation system for hydro and magnetohydrodynamics from which one can derive approximate Riemann solvers. The solvers satisfy discrete entropy inequalities, and preserve positivity of density and internal energy. Next we consider their practical implementation, and derive explicit wave speed estimates satisfying the stability conditions.

We put this into an astrophysical application by comparing our new positive and entropy stable approximate Riemann solver with state-of the-art algorithms for astrophysical fluid dynamics, the Prometheus code. The new Riemann solver increases the computational speed without loss of accuracy.

These 3-dimensional turbulence simulations are part of a plan to develop, implement, and apply a new numerical scheme for modeling turbulent, multiphase astrophysical flows. The method combines the capabilities of adaptive mesh refinement and large eddy simulations; we refer to it as Fluid mEchanics with Adaptively Refined Large Eddy SimulationS or FEARLESS. We shall present advances in this ongoing project.