Numerical modelling of strongly anisotropic dissipative effects in MHD

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Abstract

Introduction Anisotropic diffusion is a common physical phenomenon describing processes where the diffusion of some scalar quantity is directionally dependent. Anisotropic diffusive processes include Darcy’s flow for porous media, large scale turbulence where turbulence scales are anisotropic in size and heat conduction and momentum dissipation in fusion plasmas. Given the high level of anisotropy in tokamak plasmas, a numerical approximation may introduce large perpendicular errors if the magnetic field direction is strongly misaligned with the grid. Here, misaligned means that the directions of diffusion are not aligned with the grid points. Problems that may arise with highly anisotropic diffusion problems on non-aligned meshes are in general; significant numerical diffusion perpendicular to the magnetic field lines due to grid misalignment (see e.g. Umansky et al[1]), non-positivity near high gradients (see e.g. Sharma et al[2]), mesh locking, stagnation of convergence dependent on anisotropy (see e.g. Babuška and Suri[3]), convergence loss in case of variable diffusion tensor (see e.g. Günter et al[4]). To confidently perform simulations of phenomena that rely heavily on the resolution of the perpendicular temperature gradient we must apply a scheme that is robust in terms of accuracy in the case of varying anisotropy and misalignment.
Original languageEnglish
Title of host publicationProceedings of the 39th European Physical Society Conference and 16th International Congress on Plasma Physics (Stockholm, Sweden, July 2-6, 2012)
PagesP5.024/1-4
Publication statusPublished - 2012
Event39th European Physical Society Conference on Plasma Physics (EPS 2012) / 16th International Congress on Plasma Physics (ICPP 2012) - Stockholm Waterfront Congress Centre, Stockholm, Sweden
Duration: 2 Jul 20126 Jul 2012
http://epsicpp2012.spp.ee.kth.se/

Publication series

NameEurophysics Conference Abstracts
Volume36F
ISSN (Print)0378-2271

Conference

Conference39th European Physical Society Conference on Plasma Physics (EPS 2012) / 16th International Congress on Plasma Physics (ICPP 2012)
Abbreviated titleEPS/ICPP 2012
Country/TerritorySweden
CityStockholm
Period2/07/126/07/12
Internet address

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