Greifswald 2024 – scientific programme
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P: Fachverband Plasmaphysik
P 25: Poster III
P 25.5: Poster
Thursday, February 29, 2024, 16:30–18:30, ELP 6: Foyer
Numerical methods for stellarator simulations in BOUT++ — •David Bold1, Brendan Shanahan1, Jessica Bold2, and Ben Dudson3 — 1Max Plank Institute for Plasma Physics, Greifswald, Germany — 2University of Greifswald, Greifswald, Germany — 3Lawrence Livermore National Laboratory, Livermore, California, USA
There is a significant need for reliable modelling of the scrape-off layer of fusion devices, which is challenging for stellarators due to the complex geometry involved. As field aligned approaches are challenging, the Flux Coorinate Independent (FCI) method is often employed.
In the FCI grid generator, Zoidberg, the fidelity to the experimental geometry has been improved, and several improvements have been made to ensure the grid is feasible even with such challenging conditions. At the same time options have been added to reduce the fidelity and improve runtime.
For the BOUT++ framework, a new finite volume operator has been implemented that does not fail in the case of non differentiable contours. The parallel FCI operators have also been rewritten to allow MPI parallelisation of the perpendicular slices, in addition to OpenMP. Scaling will be presented, showing the improved scaling using the new PETSc-based operators. The parallel boundary conditions generally rely on points within the domain to extrapolate into the boundary. However, this breaks down in the case of short connection lengths, where a field line is outside of the domain in the previous and next plane. In this case a lower order scheme is used automatically.
Keywords: BOUT++; FCI; W7-X; Scrape off layer (SOL)