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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

When fully conservative methods are used to simulate transcritical flow, spurious pressure oscillations and numerical instability are generated. The strength and speed of propagation of shock waves cannot be represented correctly using a…

Fluid Dynamics · Physics 2022-06-24 Bonan Xu , Hanhui Jin , Yu Guo , Jianren Fan

We report on recent upgrades to our general relativistic radiation-magnetohydrodynamics code, Cosmos++, which expands the two-moment, $\bf{M}_1$, radiation treatment from grey to multi-frequency transport, including Doppler and…

Instrumentation and Methods for Astrophysics · Physics 2020-09-09 Peter Anninos , P. Chris Fragile

We consider an incompressible magnetohydrodynamics (MHD) model in which the classical first-order time derivatives in the momentum and magnetic induction equations are replaced by variable-order Caputo time-fractional derivatives. This…

Numerical Analysis · Mathematics 2026-05-06 Abdumauvlen Berdyshev , Dossan Baigereyev , Aibek Bakishev , Nurlana Alimbekova , Talgat Farkhadov

"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

We describe a conservative, shock-capturing scheme for evolving the equations of general relativistic magnetohydrodynamics. The fluxes are calculated using the Harten, Lax, and van Leer scheme. A variant of constrained transport, proposed…

Astrophysics · Physics 2009-11-07 Charles F. Gammie , Jonathan C. McKinney , Gábor Tóth

We present the derivation of hydrodynamical equations for a perfect fluid in General Relativity, within the 3+1 decomposition of spacetime framework, using only primitive variables. Primitive variables are opposed to conserved variables, as…

General Relativity and Quantum Cosmology · Physics 2023-04-17 Gaël Servignat , Jerome Novak , Isabel Cordero-Carrión

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

In this paper, we consider numerical approximations for solving the inductionless magnetohydrodynamic (MHD) equations. By utilizing the scalar auxiliary variable (SAV) approach for dealing with the convective and coupling terms, we propose…

Numerical Analysis · Mathematics 2023-03-21 Xiaodi Zhang , Xianghai Zhou

Astrophysical plasmas in relativistic spacetimes, such as black hole accretion flows, are often weakly collisional and require kinetic modeling to capture non-local transport and particle acceleration. However, the extreme scale separation…

High Energy Astrophysical Phenomena · Physics 2025-07-17 Tyler Trent , Dimitrios Psaltis , Feryal Özel

Parameterization (closure) schemes in numerical weather and climate prediction models account for the effects of physical processes that cannot be resolved explicitly by these models. Methods for finding physical parameterization schemes…

Mathematical Physics · Physics 2015-06-11 Alexander Bihlo , George Bluman

This paper presents entropy symmetrization and high-order accurate entropy stable schemes for the relativistic magnetohydrodynamic (RMHD) equations. It is shown that the conservative RMHD equations are not symmetrizable and do not admit a…

Numerical Analysis · Mathematics 2021-07-13 Kailiang Wu , Chi-Wang Shu

We describe a novel splitting approach to numerical relativistic magnetohydrodynamics (RMHD) designed to expand its applicability to the domain of ultra-high magnetisation (high-$\sigma$). In this approach, the electromagnetic field is…

High Energy Astrophysical Phenomena · Physics 2024-11-18 Serguei Komissarov , David Phillips

We describe a numerical code to solve the equations for ideal magnetohydrodynamics (MHD). It is based on an explicit finite difference scheme on an Eulerian grid, called the Total Variation Diminishing (TVD) scheme, which is a…

Astrophysics · Physics 2009-10-22 Dongsu Ryu , T. W. Jones

The current status of numerical solutions for the equations of ideal general relativistic hydrodynamics is reviewed. With respect to an earlier version of the article the present update provides additional information on numerical schemes…

General Relativity and Quantum Cosmology · Physics 2016-10-19 Jose A. Font

A fully geometrical treatment of general relativistic magnetohydrodynamics (GRMHD) is developed under the hypotheses of perfect conductivity, stationarity and axisymmetry. The spacetime is not assumed to be circular, which allows for…

General Relativity and Quantum Cosmology · Physics 2011-05-12 Eric Gourgoulhon , Charalampos Markakis , Koji Uryu , Yoshiharu Eriguchi

This work summarizes a program intended to unify three burgeoning branches of the high-energy astrophysics of relativistic jets: general relativistic magnetohydrodynamic (GRMHD) simulations of ever-increasing dynamical range, the…

Astrophysics of Galaxies · Physics 2018-05-15 Richard Anantua , Roger Blandford , Alexander Tchekhovskoy

We describe a new Godunov algorithm for relativistic magnetohydrodynamics (RMHD) that combines a simple, unsplit second order accurate integrator with the constrained transport (CT) method for enforcing the solenoidal constraint on the…

High Energy Astrophysical Phenomena · Physics 2015-05-27 Kris Beckwith , James M. Stone

Motivated by a geometric method employed for the derivation of the Nambu bracket for ideal two-dimensional incompressible hydrodynamics, we reconstruct the reduced magnetohydrodynamic (RMHD) model by a priori imposition of its conservation…

Plasma Physics · Physics 2019-02-25 D. A. Kaltsas , G. N. Throumoulopoulos

A numerical scheme is developed for systems of conservation laws on manifolds which arise in high speed aerodynamics and magneto-aerodynamics. The systems are presented in an arbitrary coordinate system on the manifold and involve source…

Analysis of PDEs · Mathematics 2019-10-22 Ian Holloway , Sivaguru S. Sritharan