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arXiv · 2005.01821

Robust Recovery of Primitive Variables in Relativistic Ideal Magnetohydrodynamics

Wolfgang Kastaun·Jay Vijay Kalinani·Riccardo Ciolfi
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Abstract

Modern simulation codes for general relativistic ideal magnetohydrodynamics are all facing a long standing technical problem given by the need to recover fundamental variables from those variables that are evolved in time. In the relativistic case, this requires the numerical solution of a system of nonlinear equations. Although several approaches are available, none has proven completely reliable. A recent study comparing different methods showed that all can fail, in particular for the important case of strong magnetization and moderate Lorentz factors. Here, we propose a new robust, efficient, and accurate solution scheme, along with a proof for the existence and uniqueness of a solution, and analytic bounds for the accuracy. Further, the scheme allows us to reliably detect evolution errors leading to unphysical states and automatically applies corrections for typical harmless cases. A reference implementation of the method is made publicly available as a software library. The aim of this library is to improve the reliability of binary neutron star merger simulations, in particular in the investigation of jet formation and magnetically driven winds.

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Wolfgang Kastaun, Jay Vijay Kalinani, Riccardo Ciolfi. 2020-05-04. Robust Recovery of Primitive Variables in Relativistic Ideal Magnetohydrodynamics. https://doi.org/10.1103/physrevd.103.023018

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