Block-Adaptive Parallel Implicit Methods for Semirelativistic Multifluid Hall-MHD

PI: Tamas Gombosi

CoIs: Darren De Zeeuw, Ken Powell, Igor Sokolov, Quentin Stout, Gabor Toth

Abstract

Space missions have transformed our understanding of space and astrophysical environments global picture. This wealth of data, however, will be of value only if we derive from these observations, and the subsequent interpretations, a clear understanding of the underlying and governing physical processes. It is here that a unifying multiscale, 3D model plays an essential role. The model must be sufficiently versatile to capture the complexity of the actual physical system. Then, by creating models that are consistent with the observations, the underlying and governing physical processes are revealed, and new phenomena, which are not currently available to observation, are suggested. This proposal requests support for the development of the next generation of such models.

We propose a five year project to develop, implement and test a solution-adaptive, parallel code for multi-fluid semirelativistic Hall MHD. The method used will be valid for magnetic fields ranging from very weak to strong enough that the Alfven speeds become relativistic. The analytical work will extwork out earlier work in ideal MHD, semi-relativistic MHD, and high-moment models for rarefied flows. The code development will build on the implicit, parallel, block-adaptive framework developed here with previous support from the AISRP program. The increased physical sophistication of the multifluid Hall model will allow us to calculate with improved fidelity space-weather events, Earth-ionosphere response, and outer-planet magnetosphere structure, as well as other applications in which resistivity and/or multiple species play a crucial role. Dealing with the additional complexity due to multiple species and the added Hall physics, as well as that due to the collisional processes, will require new development of numerical methods. In particular, work will need to be done on understanding the underlying Riemann problem of the extended equations, and on the effects that the collisional terms have on the evolution of the conservation-law system. However, this development can build on the existing framework for solution-adaptive, parallel ideal and semi-relativistic MHD, leading to a sophisticated physical model in a powerful, efficient computational framework.

This proposal meets all three goals of this solicitation. It will help to reduce mission development time, risk, and cost through advanced simulation and design capabilities. These capabilities will be relevant for missions in solar and heliospheric physics, magnetospheric physics, planetary exploration and astrophysics. Finally, it increases interdisciplinary collaboration between space scientists (Gombosi), computational scientists (De Zeeuw, Powell, Sokolov, Toth) and computer scientists (Stout). This collaboration started over a decade ago and it resulted in a tightly integrated interdisciplinary team with a series of successful projects.