JpGU-AGU Joint Meeting 2020

Presentation information

[E] Oral

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

[P-EM15] Plasma Theory and Simulation

convener:Seiji Zenitani(Kobe University), Fan Guo(Los Alamos National Laboratory), 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 Education, University of Toyama)

[PEM15-05] Outstanding issues in plasma Riemann problem

*Tohru Hada1 (1.Interdisciplinary Graduate School of Engineering Sciences, Kyushu University)

Keywords:Riemann problem, discontinuities

The Riemann problem is an initial value problem for a given physical system (such as the hydrodyanmcis (HD), magnetohydrodynamics (MHD), or plasma in general) in which the initial conditions consist of two constant states forming a discontinuity. Obviously, it has numerous applications in space plasma, e.g., the formation of planetary bow shocks, magnetopause, interplanetary shocks, heliopause, and termination shocks. Despite the importance of the problem, there remain several issues remain unsolved. In particular, the solution of the MHD Riemann problem is not always uniquely determined due to the presence of intermediate shocks (Wu, 1987; Takahashi and Yamada, 2014). In this presentation, first we will briefly review our current understanding of the MHD Riemann problem and then will propose a method to determine the solution. For practical applications to space plasma, we will also comment on how plasma kinetic effects may modify the solution qualitatively.