Japan Geoscience Union Meeting 2016

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Symbol P (Space and Planetary Sciences) » P-EM Solar-Terrestrial Sciences, Space Electromagnetism & Space Environment

[P-EM17] Space Plasma Physics: Theory and Simulation

Tue. May 24, 2016 1:45 PM - 3:15 PM 302 (3F)

Convener:*Takayuki Umeda(Institute for Space-Earth Environmental Research, Nagoya University), Takanobu Amano(Department of Earth and Planetary Science, University of Tokyo), Yasuhiro Nariyuki(Faculty of Human Development, University of Toyama), Tadas Nakamura(Fukui Prefectural University), Tooru Sugiyama(Japan Agency for Marine-Earth Science and Technology Center for Earth Information Science and Technology), Chair:Takayuki Umeda(Institute for Space-Earth Environmental Research, Nagoya University), Tadas Nakamura(Fukui Prefectural University)

2:30 PM - 2:45 PM

[PEM17-04] MHD Relaxation with Flow in a unit Sphere

*Kohei Yamamoto1, Akira Kageyama1 (1.Kobe University)

Keywords:magnetohydrodynamics, self-organization, plasma relaxation, Yin-Yang-Zhong grid

We investigate a relaxation process in a unit sphere of an electrically conducting fluid by computer simulation. We solve the magnetohydrodynamics(MHD) equations in a full sphere, including the origin at the radius r = 0, with a newly developed spherical grid system, Yin-Yang-Zhong grid (Hayashi and Kageyama, J.Comput.Phys., 2016). In the classical theory of the MHD relaxation by Woltjer and Taylor, flow in a relaxed state is supposed to be absent. On the other hand, we study relaxed states with flow. The boundary is a perfectly conducting, stress-free, and thermally insulating spherical wall. Under these conditions, the angular momentum is conserved as well as the total energy. Starting from a simple and symmetric state in which a ring-shaped magnetic flux without flow, a dynamical relaxation process of the magnetic energy is numerically integrated. The relaxed state has a characteristic structure of the flow field with four vortices. The Reynolds number Re and the magnetic Reynolds number Rm is the same: Re = Rm = 8600.