|A New Godunov Algorithm for Radiation MHD in Athena
|459, 6th International Conference of Numerical Modeling of Space Plasma Flows (ASTRONUM 2011)
|Jiang, Y.-F.; Stone, J. M.; Davis, S. W.
|Here we describe the implementation and tests of a new multi-dimension Godunov algorithm
for radiation magnetohydrodynamics (MHD) simulations based on Athena. There are several new features of this algorithm. First,
this is a Godunov method with stiff source terms from radiation field.
Second, we use a variable Eddington tensor to close the radiation
momentum equations. Thus we do not need to assume any diffusion like
approximation. This also makes the code be suitable for both optical thin
and optical thick regimes. Third, we only need to solve a set of linear equations
for the radiation subsystem, instead of a non-linear equation people
usually encounter with flux-limited diffusion approximation. We
have also developed a suite of tests, which cover a wide range of parameter
space in terms of optical depth and the ratio between radiation pressure and gas pressure,
to show that the algorithm is working accurately.