Event Detail

Event Type: 
Applied Mathematics and Computation Seminar
Date/Time: 
Friday, April 6, 2018 - 12:00 to 13:00
Location: 
STAG 210

Speaker Info

Institution: 
Sandia National Laboratories
Abstract: 

Z-machine is the most powerful laboratory radiation source in the world. The high energy densities on Z are used to create intense radiation environments, measure the state of matter at high temperatures and pressures, and as a platform for fusion research. Recent experimental results on Z indicate that target physics are fundamentally impacted by hot, low density blow off plasmas in the near feed region. Unfortunately, most target models assume high density – thus a major thrust is to extend these models into low density regimes. We discuss a conceptual modification to traditional Arbitrary Lagrangian-Eulerian (ALE) discretizations of resistive MHD, which we call Full Maxwell Hydrodynamics (FMHD). In this single fluid plasma model we do not neglect the time derivative of the electric displacement field. The potential advantages of considering FMHD include eliminating the fast magnetosonic time step limitation, removal of arbitrary, user-controlled, low density knobs in the numerical scheme, and the ability to include Coulomb forces which are typically neglected in MHD. We will describe an indirect ALE discretization of the FMHD system consisting of a Lagrangian step, remeshing, and remapping data to the new mesh. In this talk we present an Asymptotic Preserving (AP), Implicit-Explicit (IMEX) discretization of the Lagrangian step and a novel remap algorithm. This remap algorithm is a generalization of Constrained Transport which transfers information using advection in pseudo time. What makes the approach novel is that we advect with the dual of the Lie derivative, guaranteeing that remap commutes with the codifferential. This mimetic approach discretely enforces weak charge conservation. In addition to theoretical development we will present numerical results on prototypical problems.

This work was principally supported by the NNSA Science Campaigns at Sandia National Laboratories and partially supported by the Army Research Laboratory under contract number 092030326 and 014081218. Sandia National Laboratories is a multimission laboratory managed and operated by National Technology and Engineering Solutions of Sandia LLC, a wholly owned subsidiary of Honeywell International Inc., for the U.S. Department of Energy’s National Nuclear Security Administration under contract DE‐NA0003525.