Aims. The importance of radiation to the physical structure of protoplanetary
disks cannot be understated. However, protoplanetary disks evolve with time,
and so to understand disk evolution and by association, disk structure, one
should solve the combined and time-dependent equations of radiation
hydrodynamics.
Methods. We implement a new implicit radiation solver in the AZEuS adaptive
mesh refinement magnetohydrodynamics fluid code. Based on a hybrid approach
that combines frequency-dependent ray-tracing for stellar irradiation with
non-equilibrium flux limited diffusion, we solve the equations of radiation
hydrodynamics while preserving the directionality of the stellar irradiation.
The implementation permits simulations in Cartesian, cylindrical, and spherical
coordinates, on both uniform and adaptive grids.
Results. We present several hydrostatic and hydrodynamic radiation tests
which validate our implementation on uniform and adaptive grids as appropriate,
including benchmarks specifically designed for protoplanetary disks. Our
results demonstrate that the combination of a hybrid radiation algorithm with
AZEuS is an effective tool for radiation hydrodynamics studies, and produces
results which are competitive with other astrophysical radiation hydrodynamics
codes.Comment: 15 pages, 10 figures, accepted for publication in A&
