Mathematical modeling and AMR simulations on massively parallel architecture of astrophysical plasmas: application to partially ionized plasma under sun chromosphere conditions

Seminar:

Mathematical modeling and AMR simulations on massively parallel architecture of astrophysical plasmas: application to partially ionized plasma under sun chromosphere conditions
Thursday, August 29, 2019
3:30PM – 5PM
POB 6.304

Quentin Wargnier

This contribution deals with the fluid modeling of multicomponent magnetized plasmas in thermo-chemical non-equilibrium from the partially- to fully-ionized collisional regimes, aiming at simulating magnetic reconnection in Sun chromosphere conditions. Such fluid models are required for large-scale simulations by relying on high performance computing. The fluid model is derived from a kinetic theory approach, yielding a rigorous description of the dissipative and non-equilibrium effects and a well-identified mathematical structure. We start from a general system of equations that is obtained by means of a multiscale Chapman-Enskog method, based on a non-dimensional analysis accounting for the mass disparity between the electrons and heavy particles, including the influence of the electromagnetic field and transport properties. The latter are computed by using a spectral Galerkin method based on a converged Laguerre-Sonine polynomial approximation. Then, in the limit of small Debye length with respect to the characteristic scale in the solar chromosphere, we derive a two-temperature single-momentum multicomponent diffusion model coupled to Maxwell's equations, which is able to describe fully- and partially-ionized plasmas, valid for the whole range of solar chromosphere conditions.

The second contribution is the development and verification of an accurate and robust numerical strategy based on a massively parallel code with adaptive mesh refinement capability. We rely on the canop code, based on two libraries: P4EST for the adaptive mesh refinement (AMR) capability and MUTATION++ for computing the transport properties with a high level of accuracy, in order to ensure that the full spectrum of scales and the dynamics of the magnetic reconnection process are captured. Finally, we present a 2D and 3D magnetic reconnection configuration in solar chromospheric conditions and assess the potential of the numerical strategy for simulating astrophysical plasmas.

Work in collaboration with Marc Massot, Thierry Magin, Benjamin Graille and Nagi Mansour, as well as NASA SuperComputing Division of NASA Ames Research Center, and von Karman Institute, Belgium

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