A Unified Hyperbolic Model for Coupled Fluid Dynamics and Electromagnetics in Aerospace Applications Joel Thompson ∗ , Andrew Wilson † , and Trevor Moeller ‡ University of Tennessee Space Institute, Tullahoma, TN, 37388, USA Charles L. Merkle § Purdue University, West LaFayette, IN, 46907, USA This paper details the development a unified hyperbolic model for fluid dynamics coupled to electromagnetics. The advantage to the model presented is that it includes the accurate physical behavior for several plasmas of aerospace interest; it can effectively capture both magnetohydrodynamic and electrohydrodynamic limits of the plasma, in addition to low-conductivity effects that expose the wave nature of the electromagnetic field. The approach is useful because of its potential for simplifying existing implementations towards multiphysics simu- lations of aerospace plasmas, eliminating the need for multiple implementations for different plasma models. In previous work, a Riemann solver approach and a flux-splitting approach have been introduced for this model. Here, we review their individual merits, present some assessment simulation results using both approaches, and compare them. I. Introduction T he application of electrodynamic fields to shape, control or propel a working fluid has a long and rich history, and yet continues to offer promise in our efforts to further improve efficiencies of flight and propulsion technologies under active development, as well as providing completely new alternatives to coping with the same problems. The specific applications of high-specific-impulse space plasma thrusters, 1 plasma actuators, 2 magnetohydrodynamic by- pass arrangements in scramjets, 3 and the application of magnetic fields to push strong bow shocks away from the nose of vehicles 4 are all examples under active study for the utilization of electromagnetically controlled plasma for the purposes of flight and propulsion. Constructing an accurate physical model for the coupled fluid dynamics and electromagnetics of a plasma is chal- lenging because the different forms of coupling can lead to widely different physical behavior. This often implies that completely separate physical models must be constructed for each form of plasma that is of interest to the aerospace community, and in turn requires that several different implementations are needed for robust modeling of these differ- ent models, which is antithetical to the spirit of developing multi-physics simulation models that can incorporate these disparately different physics. This paper summarizes recent efforts to develop a unified hyperbolic model for coupling between the fluid dynam- ics and electromagnetics that includes a wider variety of these limiting cases in a single finite volume implementation. Of course, these different physical phenomena are characterized by highly disparate frequencies, and so capturing all of these physics in an accurate and yet computationally modest manner proves challenging, but recent investigations have realized successful methods of circumventing these difficulties such that reasonably efficient methods may be implemented to solve the resulting unified model. 5, 6 Much of the success of this method is owed to the computational approach suggested by Li, et al., 7 and demonstrated by Thompson, et al. 5, 6, 8 This involves casting the equations into a strong conservative form, which eliminates the explicit appearance of source terms, while retaining an exact coupling between the Navier-Stokes and full Maxwell equations, including charge non-neutrality effects, displacement current ∗ Postdoctoral Research Associate, Dept. of Mechanical, Aerospace & Biomedical Engineering, 411 B. H. Goethert Pkwy, AIAA Young Profes- sional Member. † Postdoctoral Research Associate, Dept. of Mechanical, Aerospace & Biomedical Engineering, 411 B. H. Goethert Pkwy, AIAA Young Profes- sional Member. ‡ Assistant Professor, Dept. of Mechanical, Aerospace & Biomedical Engineering, 411 B. H. Goethert Pkwy MS24, AIAA Associate Fellow. § Emeritus Reilly Professor of Engineering, Dept. of Aeronautics and Astronautics, 585 Purdue Mall, AIAA Member. 1 of 9 American Institute of Aeronautics and Astronautics