SM54A-07
Magnetospheric Simulations With the Three-Dimensional Magnetohydrodynamics With Embedded Particle-in-Cell Model

Friday, 18 December 2015: 17:30
2016 (Moscone West)
Gabor Toth1, Xianzhe Jia2, Yuxi Chen2, Stefano Markidis3, Bo Peng3, Lars K. S. Daldorff4, Valeriy Tenishev1, Dmitry Borovikov2, John David Haiducek2, Tamas I Gombosi5, Alex Glocer4, John Dorelli4 and Giovanni Lapenta6, (1)University of Michigan, Ann Arbor, MI, United States, (2)University of Michigan Ann Arbor, Ann Arbor, MI, United States, (3)KTH Royal Institute of Technology, Stockholm, Sweden, (4)NASA Goddard Space Flight Center, Greenbelt, MD, United States, (5)Univ of Michigan, Ann Arbor, MI, United States, (6)Katholieke Universiteit Leuven, Leuven, Belgium
Abstract:
We have recently developed a new modeling capability to embed the implicit Particle-in-Cell (PIC) model iPIC3D into the BATS-R-US magnetohydrodynamic model. The PIC domain can cover the regions where kinetic effects are most important, such as reconnection sites. The BATS-R-US code, on the other hand, can efficiently handle the rest of the computational domain where the MHD or Hall MHD description is sufficient with its block-adaptive grid. The current implementation of the MHD-EPIC model allows two-way coupled simulations in two and three dimensions with multiple embedded PIC regions. The MHD and PIC grids can have different grid resolutions. The MHD variables and the moments of the PIC distribution functions are interpolated and message passed in an efficient manner through the Space Weather Modeling Framework (SWMF). Both BATS-R-US and iPIC3D are massively parallel codes fully integrated into, run by and coupled through the SWMF.

We have successfully applied the MHD-EPIC code to model Ganymede's magnetosphere. Using four PIC regions we have in effect performed a fully kinetic simulation of the moon's mini-magnetosphere with a grid resolution that is about 5 times finer than the ion inertial length. The Hall MHD model provides proper boundary conditions for the four PIC regions and connects them with each other and with the inner and outer outer boundary conditions of the much larger MHD domain. We compare our results with Galileo magnetic observations and find good overall agreement with both Hall MHD and MHD-EPIC simulations. The power spectrum for the small scale fluctuations, however, agrees with the data much better for the MHD-EPIC simulation than for Hall MHD. In the MHD-EPIC simulation, unlike in the pure Hall MHD results, we also find signatures of flux transfer events (FTEs) that agree very well with the observed FTE signatures both in terms of shape and amplitudes. We will also highlight our ongoing efforts to model the magnetospheres of Mercury and Earth with the MHD-EPIC model.

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