Abstract Details
Abstracts
Author: Sean T Miller
Requested Type: Poster
Submitted: 2017-03-15 09:35:08
Co-authors: E.C.Cyr, J.N.Shadid, E.G.Phillips
Contact Info:
Sandia National Lab
1515 Eubank SE
Albuquerque, New Mexico 87123
USA
Abstract Text:
Multi-fluid plasma models, where an electron fluid is modeled alongside multiple ion and neutral species as well as the full set of Maxwell’s equations, can represent physics beyond the scope of classic MHD. The drawback being that these models resolve electron dynamics and electromagnetics characterized by the plasma and cyclotron frequencies as well as the speed of light, which drastically increase runtimes for explicit time integrators. Implicit time integration schemes help alleviate this issue by stepping over these stiff time scales at the cost of accuracy. To do so, implicit schemes must solve a large system of stiff equations which can require complex preconditioning schemes to achieve convergence. For most applications, a fully implicit scheme is overkill since ion and neutral dynamics are much slower than electron and electromagnetic time scales. Mixed implicit-explicit (IMEX) integration provides a mechanism to choose which dynamics to resolve using either a complex and slow implicit solve or a simple and fast explicit solve. Removing slow dynamics from the implicit solve reduces the condition of the solution method thereby reducing runtimes. The use of compatible spatial discretizations, meaning coupling a nodal (H-Grad) basis for fluid dynamics with a sets of vector (H-Div and H-Curl) bases for Maxwell’s equations, allows us to safely evolve electromagnetics without violating Gauss’ laws for the electric and magnetic fields. The goal of this research is to develop robust methods for capturing multi-species plasma physics associated electrons and electromagnetics with runtimes more commonly associated with MHD solvers.
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