Event

A VEF HOLO Radiation-Hydrodynamics Method with Independent Discretizations for the Sn and Low-order Moment Equations

Dr Jim Morel

Abstract: We present a High-Order/Low-Order radiation-hydrodynamics method that is   second-order accurate in both space and time and uses the Variable Eddington Factor (VEF) method to couple a high-order set of 1-D slab-geometry grey Sn radiation transport equations with a low-order set of radiation moment and hydrodynamics equations.  The Sn equations are spatially discretized with a lumped linear-discontinuous Galerkin scheme, while the low-order radiation-hydrodynamics equations are spatially discretized with a constant-linear mixed finite-element scheme. Both the high-order and low-order equations are discretized in time using a trapezoidal BDF-2 method.  A manufactured solution is used to demonstrate that the scheme is second-order accurate for smooth solutions, and calculations are performed for radiative shock problems and compared with semi-analytic solutions. The pure radiative transfer scheme is shown to be asymptotic preserving in the equilibrium-diffusion limit, well behaved with unresolved spatial boundary layers, and to yield accurate Marshak wave speeds even with strongly temperature-dependent opacities and relatively coarse meshes.  These same properties carry over to our radiation-hydrodynamics scheme.

Speaker’s Bio:  Professor Jim E. Morel received a B.S. in mathematics from Louisiana State University in 1972, an M.S. in nuclear engineering from Louisiana State University in 1974, and a Ph.D. in nuclear engineering from the University of New Mexico in 1979. He began his career in 1974 as a nuclear research officer at the Air Force Weapons Laboratory. In 1976 he became a staff scientist at Sandia National Laboratories. In 1984 he became a staff member at Los Alamos National Laboratory, eventually serving as a group leader and scientific advisor. In 2005 he accepted a professorship in the Department of Nuclear Engineering at Texas A&M University (http://nuclear.tamu.edu/). In 2007 he became Director of the Center for Large Scale Scientific Simulations at TAMU (http://class.tamu.edu). He has published 114 journal articles, 81 refereed full conference papers, and 27 refereed conference summaries relating to numerical methods for neutral particle transport, charged-particle transport, thermal radiation transport, and radiation-hydrodynamics.