Erlangen 2018 – wissenschaftliches Programm
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P: Fachverband Plasmaphysik
P 11: Helmholtz Graduate School - Poster
P 11.33: Poster
Dienstag, 6. März 2018, 16:15–18:15, Redoutensaal
Relaxation of fluid theories by metriplectic dynamics: a method based on a generalization of the Landau collision operator — •Camilla Bressan1,2, Michael Kraus1,2, Philip James Morrison3, and Omar Maj1,2 — 1Max-Planck-Institute for Plasma Physics, Garching, Germany — 2Technische Universität München, Zentrum Mathematik, Garching, Germany — 3The University of Texas at Austin, Physics Department and Institute for Fusion Studies, USA
The computation of general 3D MHD equilibria plays a fundamental role in Stellarator as well as in Tokamak simulations in which 3D effects (namely islands, ripples and resonant magnetic perturbations) are increasingly important.
A novel relaxation method based on the paradigm of metriplectic dynamics [P.J.Morrison, Physica D, 18, 410-419 (1986)] is proposed. This specific relaxation mechanism has the same structure as the Landau collision operator, so that its equilibrium points can be understood in terms of local extrema of an entropy functional. No restrictive assumption on the topology of the magnetic field is made. In fact it allows for the formation of magnetic islands and stochastic regions, while maintaining a control on relaxed equilibrium profiles.
The new approach has been numerically tested on both the Euler ideal fluid equations in two dimensions and Grad-Shafranov MHD equilibria. First steps toward a proof of concept for 3D MHD are discussed.