The International Conference for High Performance Computing, Networking, Storage and Analysis
Vlasiator: Hybrid-Vlasov Simulation Code for the Earth's Magnetosphere.
Authors: Sebastian von Alfthan (Finnish Meteorological Institute), Dimitry Pokhotelov (Department of Physics, University of Helsinki), Yann Kempf (Finnish Meteorological Institute, University of Helsinki), Ilja Honkonen (Finnish Meteorological Institute, University of Helsinki), Sanni Hoilijoki (Finnish Meteorological Institute, University of Helsinki), Arto Sandroos (Finnish Meteorological Institute), Minna Palmroth (Finnish Meteorological Institute)
Abstract: Here we present Vlasiator, the first global magnetospheric simulation code based on a hybrid-Vlasov description of plasma. Ions are represented by a six-dimensional distribution function, while electrons are modeled as a charge neutralizing fluid. To propagate the distribution function we use a finite volume method, coupled to an upwind constrained transport method for propagating electromagnetic fields. We have parallelized the code with a two-level MPI and OpenMP scheme, and it scales well to tens of thousands of cores. The hybrid-Vlasov approach is enabled through a novel sparse representation of the distribution function that reduces the problem size by more than two orders of magnitude. The capabilities of the code are demonstrated by reproducing key features of the collisionless bowshock in a global five-dimensional magnetospheric simulation. Vlasiator produces the first uniformly discretized ion velocity distribution functions with quality comparable to spacecraft measurements, opening up new opportunities for studying the Earth’s magnetosphere.