11:40 AM - 12:00 PM (20 min)

The joy of primitive variable recovery in relativistic magnetohydrodynamics

Wolfgang Kastaun (Max Planck Institute for Gravitational Physics)

Abstract: Modern evolution codes for general relativistic magnetohydrodynamic are all based on evolution equations in form of a conservation law. The evolved variables depend on the fundamental (primitive) variables such as density and velocity in a nonlinear fashion that has proven difficult to invert robustly. One problem is the need to cover wastly different regimes from magnetically dominated to non-magnetized, and from the Newtonian limit to highly relativistic cases. Another problem is the need to handle physically invalid combinations of the evolved variables caused by evolution errors. Failure of the primitive variable recovery has been a major and persistent source of problems for such simulations. I will describe the problem and summarize various approaches, with focus on a new public library I recently made public.

slides: slides.pdf
recording: watch

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