Conference Paper Validation Study On Upwinding Schemes For Core MHD/Turbulent Simulation

瀬戸, 春樹  ,  矢木, 雅敏

Description
The validity of upwinding schemes for core MHD/turbulent simulation is numerically investigated by the used of a fully linearized 3-field resistive ballooning mode (RBM) model with three different discretiza- tion schemes on a convective derivative, (1) 4th order central differential (C4), (2) 4th order linear upwinding scheme (U4), (3) 3rd order weighted essentially non-oscillatory (WENO) scheme (W3). The simulations reveal that, in the cases with U4 and W3, the temporally varying upwinding direction can be unphysical nonlinear energy channels among toroidal modes and drive unphysical mode transitions even if the equation system is fully linearized theoretically. On the other hand, growth rates and eigen functions of RBM are conserved over the simulation time in the case with C4. These result show that any upwinding scheme should not be employed in the core region where nonlinear wave couplings described by convective derivatives such as the ExB flow term and the magnetic fluttering term are the fundamental nature of plasma instability and turbulence.

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