Radiation hydrodynamics including irradiation and adaptive mesh refinement with AZEuS. I. Methods

TL;DR

This paper introduces a new implicit radiation solver integrated into the AZEuS adaptive mesh refinement code, enabling accurate, multi-dimensional radiation hydrodynamics simulations of protoplanetary disks with complex geometries.

Contribution

The paper presents a novel hybrid radiation algorithm implementation in AZEuS that combines ray-tracing and flux-limited diffusion, allowing for detailed, time-dependent radiation hydrodynamics simulations.

Findings

Validated the implementation with hydrostatic and hydrodynamic tests.

Demonstrated effectiveness for protoplanetary disk simulations.

Achieved results competitive with existing astrophysical radiation codes.

Abstract

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.