Multigroup Radiation Hydrodynamics with a High-Order–Low-Order Method

Abstract

Recent efforts at Los Alamos National Laboratory to develop a moment-based, scale-bridging [or high-order (HO)–low-order (LO)] algorithm for solving large varieties of the transport (kinetic) systems have shown promising results. A part of our ongoing effort is incorporating this methodology into the framework of the Eulerian Applications Project to achieve algorithmic acceleration of radiation-hydrodynamics simulations in production software. By starting from the thermal radiative transfer equations with a simple material-motion correction, we derive a discretely consistent energy balance equation (LO equation). We demonstrate that the corresponding LO system for the Monte Carlo HO solver is closely related to the original LO system without material-motion corrections. We test the implementation on a radiative shock problem and show consistency between the energy densities and temperatures in the HO and LO solutions as well as agreement with the semianalytic solution. We also test the approach on a more challenging two-dimensional problem and demonstrate accuracy enhancements and algorithmic speedups. This paper extends a recent conference paper by including multigroup effects.

• Radiation hydrodynamics
• moment-based scale-bridging algorithm
• thermal radiative transfer

Acknowledgments

This information has been authored by employees of Los Alamos National Security, LLC, operator of Los Alamos National Laboratory under contract DE-AC52-06NA25396 with the U.S. Department of Energy.

Notes

^aThis procedure is identical for the IMC operator split with Eq. (10b)(10b) replaced by the IMC transport equation. We also note that in step Eq. (10c)(10c) , if there is insufficient energy in the census to account for the kinetic energy exchange, then we reduce both the census energy and the momentum deposition to account for this and maintain total energy conservation.