Hybridized SLAU2-HLLI Riemann Solver for Magnetohydrodynamics Simulations

摘要

SLAU2 (Kitamura and Shima JCP 2013), one of AUSM-type solvers, has been extended to magnetohydrodynamics (MHD). At higher Mach numbers, however, SLAU2 was found not to function well for some MHD Riemann problems. The HLLI Riemann solver (Dumbser and Balsara JCP 2016) has a dissipation which makes it unsuitable for low Mach number flows. However, it has very favorable performance for higher Mach number MHD flows. Since the two families of Riemann solvers both perform very well over a range of intermediate Mach numbers, the best way to benefit from the mutually complementary strengths of both these Riemann solvers is to hybridize between them. The result is an all-speed Riemann solver for MHD. We, therefore, document a hybridized SLAU2-HLLI Riemann solver. The hybrid Riemann solver suppresses the oscillations that appeared in single solver solutions, and it also preserves contact discontinuities, as well as Alfven waves, very well.