Rosen, Anna L.Krumholz, MarkOishi, J. S.Lee, A. T.Klein, Richard I.2021-05-270021-9991http://hdl.handle.net/1885/234538We present a highly-parallel multi-frequency hybrid radiation hydrodynamics algorithm that combines a spatially-adaptive long characteristics method for the radiation field from point sources with a moment method that handles the diffuse radiation field produced by a volume-filling fluid. Our Hybrid Adaptive Ray-Moment Method (HARM2) operates on patchbased adaptive grids, is compatible with asynchronous time stepping, and works with any moment method. In comparison to previous long characteristics methods, we have greatly improved the parallel performance of the adaptive long-characteristics method by developing a new completely asynchronous and non-blocking communication algorithm. As a result of this improvement, our implementation achieves near-perfect scaling up to O(103) processors on distributed memory machines. We present a series of tests to demonstrate the accuracy and performance of the method.ALR and MRK acknowledge support from the National Aeronautics and Space Administration (NASA) through Hubble Archival Research grant HST-AR-13265.02-A issued by the Space Telescope Science Institute, which is operated by the Association of Universities for Research in Astronomy, Inc., under NASA contract NAS 5-26555 and Chandra Theory Grant Award Number TM5-16007X issued by the Chandra X-ray Observatory Center, which is operated by the Smithsonian Astrophysical Observatory for and on behalf of NASA under contract NAS8-03060. ALR and ATL acknowledge support from the NSF Graduate Research Fellowship Program (number DGE-0809125). RIK acknowledges support from NASA through ATP grant NNX13AB84G, the NSF through grant AST-1211729 and the US Department of Energy at the Lawrence Livermore National Laboratory under contract DE-AC52-07NA27344. MRK and RIK acknowledge support from NASA TCAN grant NNX-14AB52G. MRK acknowledges support from Australian Research Council grant DP160100695.application/pdfen-AU© 2016 Elsevier Inc.https://creativecommons.org/licenses/by-nc-nd/4.0/Radiative transferHydrodynamicsParallelizationLong characteristicsAdaptive mesh refinement201710.1016/j.jcp.2016.10.0482020-11-23CC BY-NC-ND