Plasma VIP Seminar

Dr. Hideaki Miura, National Institute for Fusion Studies

"Two-fluid Large eddy simulations of ballooning mode in a Heliotron device"

4:00pm, RLM 11.204

Abstract: A Large Eddy Simulation (LES) approach is introduced to enable study of the nonlinear growth of ballooning modes in a Heliotron type device over a wide range of parameter space, keeping computational costs as low as possible. A model to substitute influences of the scales smaller than the grid size, Sub-Grid-Scale (SGS), on the scales larger than it, Grid Scale (GS), is developed for LES. LESes of two-fluid MHD equations with the SGS models successfully reproduce growth of the ballooning modes in the GS and nonlinear saturation. The numerical results show an importance of SGS effects on the GS components in the course of nonlinear saturation process. It is shown through the parameter survey over many SGS model coefficients that turbulent small-scale components in experiments can contribute to keep plasma core pressure away from a total collapse.