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The detection of gravitational waves has opened a new era for astronomy, allowing for the combined use of gravitational wave and electromagnetic emissions to directly probe the physics of compact objects, still poorly understood. So far,…

General Relativity and Quantum Cosmology · Physics 2023-01-05 Alessandro Lupi

A generalization of implicit conservative numerics to multiple dimensions requires advanced concepts of tensor analysis and differential geometry and hence a more thorough dedication to mathematical fundamentals than maybe expected at first…

Instrumentation and Methods for Astrophysics · Physics 2012-10-19 Harald Höller

We present a new numerical algorithm to solve the recently derived equations of two-moment cosmic ray hydrodynamics (CRHD). The algorithm is implemented as a module in the moving mesh Arepo code. Therein, the anisotropic transport of cosmic…

High Energy Astrophysical Phenomena · Physics 2021-02-24 Timon Thomas , Christoph Pfrommer , Rüdiger Pakmor

A third order shock-capturing numerical scheme for three-dimensional special relativistic magnetohydrodynamics (3-D RMHD) is presented and validated against several numerical tests. The simple and efficient central scheme described in Paper…

Astrophysics · Physics 2009-11-07 L. Del Zanna , N. Bucciantini , P. Londrillo

We present a new computational method for smoothly matching general relativistic ideal magnetohydrodynamics (MHD) to its force-free limit. The method is based on a flux-conservative formalism for MHD and its force-free limit, and a vector…

High Energy Astrophysical Phenomena · Physics 2015-06-17 Vasileios Paschalidis , Stuart L. Shapiro

The magnetohydrodynamics (MHD) equations are continuum models used in the study of a wide range of plasma physics systems, including the evolution of complex plasma dynamics in tokamak disruptions. However, efficient numerical solution…

Computational Physics · Physics 2022-02-09 Qi Tang , Luis Chacon , Tzanio V. Kolev , John N. Shadid , Xian-Zhu Tang

In certain astrophysical systems the commonly employed ideal magnetohydrodynamics (MHD) approximation breaks down. Here, we introduce novel explicit and implicit numerical schemes of ohmic resistivity terms in the moving-mesh code AREPO. We…

Instrumentation and Methods for Astrophysics · Physics 2018-03-09 Federico Marinacci , Mark Vogelsberger , Rahul Kannan , Philip Mocz , Rüdiger Pakmor , Volker Springel

We have developed a new computer code, RAM, to solve the conservative equations of special relativistic hydrodynamics (SRHD) using adaptive mesh refinement (AMR) on parallel computers. We have implemented a characteristic-wise, finite…

Astrophysics · Physics 2009-11-11 Weiqun Zhang , Andrew I. MacFadyen

We consider the relativistic hydrodynamics of non-perfect fluids with the goal of determining a formulation that is suited for numerical integration in special-relativistic and general-relativistic scenarios. To this end, we review the…

General Relativity and Quantum Cosmology · Physics 2023-02-27 Michail Chabanov , Luciano Rezzolla , Dirk H. Rischke

We present a novel spectral solver for general relativistic magnetohydrodynamics on dynamical spacetimes. By combining a high order discontinuous spectral method on mapped Chebyshev Fourier grids, our scheme attains exponential convergence.…

High Energy Astrophysical Phenomena · Physics 2025-08-26 Beibei Li

Magnetohydrodynamics (MHD) couples the Navier--Stokes and Maxwell equations into a nonlinear system of partial differential equations governing stellar interiors, astrophysical jets, fusion plasmas, and space weather. Numerical advances,…

High Energy Astrophysical Phenomena · Physics 2026-05-20 E. A. Huerta

We present a new approach for stably evolving general relativistic magnetohydrodynamic (GRMHD) simulations in regions where the magnetization $\sigma=b^2/\rho c^2$ becomes large. GRMHD codes typically struggle to evolve plasma above…

High Energy Astrophysical Phenomena · Physics 2024-07-16 Andrew Chael

We present a new special relativistic hydrodynamics (SRHD) code capable of handling coexisting ultra-relativistically hot and non-relativistically cold gases. We achieve this by designing a new algorithm for conversion between primitive and…

High Energy Astrophysical Phenomena · Physics 2021-04-21 Po-Hsun Tseng , Hsi-Yu Schive , Tzihong Chiueh

The magnetohydrodynamics (MHD) equations are generally known to be difficult to solve numerically, due to their highly nonlinear structure and the strong coupling between the electromagnetic and hydrodynamic variables, especially for high…

Numerical Analysis · Mathematics 2022-11-11 Fabian Laakmann , Patrick E. Farrell , Lawrence Mitchell

Relativistic macroscopic plasma dynamics can be described by general-relativistic magnetohydrodynamics. In many high-energy astrophysical settings, such as the interior dynamics of magnetized stars, the ideal GRMHD approximation, in which…

High Energy Astrophysical Phenomena · Physics 2025-10-23 Sara Azizi , Swapnil Shankar , Philipp Mösta , Roland Haas , Erik Schnetter

We have extended Cosmos++, a multi-dimensional unstructured adaptive mesh code for solving the covariant Newtonian and general relativistic radiation magnetohydrodynamic (MHD) equations, to accommodate both discrete finite volume and…

Instrumentation and Methods for Astrophysics · Physics 2017-08-23 Peter Anninos , Colton Bryant , P. Chris Fragile , A. Miguel Holgado , Cheuk Lau , Daniel Nemergut

We present a new implementation of radiation hydrodynamics (RHD) in the adaptive mesh refinement (AMR) code RAMSES. The multi-group radiative transfer (RT) is performed on the AMR grid with a first-order Godunov method using the M1 closure…

Cosmology and Nongalactic Astrophysics · Physics 2015-06-15 Joakim Rosdahl , Jeremy Blaizot , Dominique Aubert , Timothy Stranex , Romain Teyssier

We extend recently-developed mesh-free Lagrangian methods for numerical magnetohydrodynamics (MHD) to arbitrary anisotropic diffusion equations, including: passive scalar diffusion, Spitzer-Braginskii conduction and viscosity, cosmic ray…

Instrumentation and Methods for Astrophysics · Physics 2017-07-11 Philip F. Hopkins

We propose and analyze a new method for the unsteady incompressible magnetohydrodynamics equations on convex domains with hybrid approximations of both vector-valued and scalar-valued fields. The proposed method is convection-semirobust,…

Numerical Analysis · Mathematics 2026-02-11 Daniele A. Di Pietro , Jerome Droniou , Vito Patierno

"Generalized Hydrodynamics" (GHD) stands for a model that describes one-dimensional \textit{integrable} systems in quantum physics, such as ultra-cold atoms or spin chains. Mathematically, GHD corresponds to nonlinear equations of kinetic…

Computational Physics · Physics 2023-11-21 Frederik Møller , Nicolas Besse , Igor E. Mazets , Hans-Peter Stimming , Norbert J. Mauser