Computational Physics and Methods Group (CCS-2)

Los Alamos National Laboratory

Los Alamos National Laboratory

• Proved that the primary Discontinuous Galerkin-based discretization of the S_N transport equations used in the Capsaicin production thermal radiative transfer code will not preserve the asymptotic diffusion limit on adaptively refined meshes; used the theory to propose modifications that do preserve this limit
• Developing high-order low-order schemes with implicit-explicit time integration to significantly reduce the number of high-dimensional transport sweeps required in thermal radiative transfer simulations; investigating the feasibility of high-order, holistic time integration for tightly coupled radiation-hydrodynamics problems
• Advising the implementation of the Second Moment Methods (SMMs) I developed in my dissertation into LANL's Capsaicin code and LLNL's next-generation, production thermal radiative transfer code, RADAR
• Mentoring a student at UCB/LLNL who is using a SMM to design a hybrid deterministic-stochastic method that has cost independent of the mean free path

University of California, Berkeley

• Developed Variable Eddington Factor (VEF) and Second Moment methods to efficiently solve the radiation transport equation on curved meshes with arbitrary-order accuracy
• Demonstrated these methods can be effectively preconditioned to solve independent of the mesh size and polynomial order on challenging proxy problems from thermal radiative transfer
• These methods have received programmatic funding at both LLNL and LANL to implement them in their production radiation-hydroynamics codes

Lawrence Livermore National Laboratory

• Performed parallel scaling analysis of the Discontinuous Galerkin-based VEF method
• Investigated extension of VEF discretizations to RZ geometry

Lawrence Livermore National Laboratory

• Explored iterative solvers for the solution of the VEF equations discretized with the mixed finite element method

Los Alamos National Laboratory

• Developed a "fully local" quasidiffusion method and implemented it in Capsaicin, a production thermal radiative transfer code at LANL

Lawrence Livermore National Laboratory

• Developed a high-order mixed finite element discretization for the VEF equations in 2/3D
• Implemented VEF in an LLNL thermal radiative transfer research code

Lawrence Livermore National Laboratory

• Designed and implemented a generalized nuclear reaction network in Cosmos++, an LLNL astrophysics code
• Created a massively parallel nucleosynthesis post-processor
• Used the generalized network and post-processor to investigate tidal disruption in white dwarfs, resulted in a publication

Center for Exascale Radiation Transport (TAMU)

• Developed a 1D mixed finite element discretization of the VEF equations

Lawrence Livermore National Laboratory

• Implemented a 19 isotope nuclear reaction network in Cosmos++

Fuel Cycle and Materials Laboratory (TAMU)

• Designed an electrorefiner to purify depleted uranium metal with non-aqueous electrolysis