A Domain-Hybridized Plasma Model Using Discontinuous Galerkin Finite Elements

Abstract

Plasmas are found all over the Universe and exhibit varying properties depending on temperature, density, field strength, and collisionality. Thus, various physics models can be used to describe plasma dynamics. This work uses the WARPXM discontinuous Galerkin finite element framework developed at the University of Washington to develop a domain-hybridized model incorporating MHD, multi-fluid, and continuum kinetic models to perform simulations in which different models are applied in different subdomains on an unstructured mesh, dictated by the underlying physics. As part of this work, the MHD and continuum kinetic models are developed, the latter in up to 2D2V using a duoprism phase space element constructed from tensor products of triangular elements in an unstructured physical space and lines in velocity space. The hybrid model is formulated using two methods. The first is a direct variable translation method which converts variables at model interfaces to be consistent with the lower fidelity model. The second is a conservative method which ensures the flux at model boundaries are equal and opposite for the adjacent models. The coupling between the continuum kinetic model and the multi-fluid model is specifically studied in this work using a variety of simulations to test these coupling methods.