Castro: A new compressible astrophysical solver. III. Multigroup radiation hydrodynamics

W. Zhang, L. Howell, A. Almgren, Adam S. Burrows, J. Dolence, J. Bell

Research output: Contribution to journalArticlepeer-review

47 Scopus citations


We present a formulation for multigroup radiation hydrodynamics that is correct to order O(v/c) using the comoving-frame approach and the flux-limited diffusion approximation. We describe a numerical algorithm for solving the system, implemented in the compressible astrophysics code, CASTRO. CASTRO uses a Eulerian grid with block-structured adaptive mesh refinement based on a nested hierarchy of logically rectangular variable-sized grids with simultaneous refinement in both space and time. In our multigroup radiation solver, the system is split into three parts: one part that couples the radiation and fluid in a hyperbolic subsystem, another part that advects the radiation in frequency space, and a parabolic part that evolves radiation diffusion and source-sink terms. The hyperbolic subsystem and the frequency space advection are solved explicitly with high-order Godunov schemes, whereas the parabolic part is solved implicitly with a first-order backward Euler method. Our multigroup radiation solver works for both neutrino and photon radiation.

Original languageEnglish (US)
Article number7
JournalAstrophysical Journal, Supplement Series
Issue number1
StatePublished - Jan 2013

All Science Journal Classification (ASJC) codes

  • Astronomy and Astrophysics
  • Space and Planetary Science


  • diffusion
  • hydrodynamics
  • methods: numerical
  • radiative transfer


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