A domain-decomposed multi-model plasma simulation of collisionless magnetic reconnection

Plasmas exhibit different properties depending on their degree of magnetization, charge separation, and collisionality. This implies a requirement for modeling different physics within different regimes. Work on simulation of collisionless magnetic reconnection in the past has shown that in some areas of the domain, a fluid model may provide sufficient physical accuracy while in others a kinetic model may be required, though at higher computational expense. This motivates an investigation of the collisionless magnetic reconnection phenomenon using a hybrid approach incorporating multiple models, including Hall-MHD, multi-fluid 5N-moment, and multi-species continuum kinetics on a domain-decomposed grid in physical space. The investigations are performed using the WARPXM code developed at the University of Washington, which uses a discontinuous Galerkin Runge-Kutta finite element algorithm on an unstructured mesh, implementing boundary conditions between models at subdomain interfaces to couple between each model's variables. The goal of this work is to determine the parameter regimes most appropriate for each model to maintain sufficient physical fidelity over the whole domain while minimizing computational expense.