Radiation diffusion for multi-fluid Eulerian hydrodynamics with adaptive mesh refinement

Block-structured meshes provide the ability to concentrate grid points and computational effort in interesting regions of a flow field, without sacrificing the efficiency and low memory requirements of a regular grid. We describe an algorithm for simulating radiation diffusion on such a mesh, coupled to multi-fluid gasdynamics. Conservation laws are enforced by using locally conservative difference schemes along with explicit synchronization operations between different levels of refinement. In unsteady calculations each refinement level is advanced at its own optimal timestep. Particular attention is given to the appropriate coupling between the fluid energy and the radiation field, the behavior of the discretization at sharp interfaces, and the form of synchronization between levels required for energy conservation in the diffusion process. Two- and three-dimensional examples are presented, including parallel calculations performed on an IBM SP-2.