Ameliorating the Courant-Friedrichs-Lewy condition in spherical coordinates: A double FFT filter method for general relativistic MHD in dynamical spacetimes

• DOI: 10.1103/physrevd.108.104005
• Publication Date: 2023-11-03T14:13:31Z
• Authors: Liwei Ji; Vassilios Mewes; Yosef Zlochower; Lorenzo Ennoggi; Federico G. Lopez...; Manuela Campanelli; Federico Cipolletta; Zachariah B. Etienne
• Keywords: Robustness; Barycentric coordinate system

Numerical simulations of merging compact objects and their remnants form the theoretical foundation for gravitational wave multimessenger astronomy. While Cartesian-coordinate-based adaptive mesh refinement is commonly used simulations, spherical-like coordinates are more suitable nearly spherical azimuthal flows due to lower numerical dissipation in evolution fluid angular momentum, as well requiring fewer numbers computational cells. However, use numerically solve hyperbolic partial differential equations can result severe Courant-Friedrichs-Lewy (CFL) stability condition time step limitations, which make prohibitively expensive. This paper addresses this issue solution coupled spacetime general relativistic magnetohydrodynamics evolutions by introducing a double fast Fourier transform (FFT) filter implementing it within fully message passing interface (mpi)-parallelized sphericalnr framework einstein toolkit. We demonstrate effectiveness robustness filtering algorithm applying number challenging code tests, show that passes these tests effectively, demonstrating convergence while also increasing significantly compared unfiltered simulations.