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We describe the implementation of sophisticated numerical techniques for general-relativistic magnetohydrodynamics simulations in the Athena++ code framework. Improvements over many existing codes include the use of advanced Riemann solvers…

High Energy Astrophysical Phenomena · Physics 2019-06-25 Christopher J. White

In this paper, we propose and analyze a temporally second-order accurate, fully discrete finite element method for the magnetohydrodynamic (MHD) equations. A modified Crank--Nicolson method is used to discretize the model and appropriate…

Numerical Analysis · Mathematics 2021-08-13 Cheng Wang , Jilu Wang , Zeyu Xia , Liwei Xu

We present an adaptive-order positivity-preserving conservative finite-difference scheme that allows a high-order solution away from shocks and discontinuities while guaranteeing positivity and robustness at discontinuities. This is…

This paper describes a multidimensional hydrodynamic code which can be used for studies of relativistic astrophysical flows. The code solves the special relativistic hydrodynamic equations as a hyperbolic system of conservation laws based…

Astrophysics · Physics 2009-11-13 Eunwoo Choi , Dongsu Ryu

Invariant finite-difference schemes for the one-dimensional shallow water equations in the presence of a magnetic field for various bottom topographies are constructed. Based on the results of the group classification recently carried out…

Numerical Analysis · Mathematics 2024-02-28 E. I. Kaptsov , V. A. Dorodnitsyn

This paper offers the exact analytical solutions for the magnetohydrodynamic (MHD) flow of an incompressible generalized Burgers fluid corresponding to the second problem of Stokes in the presence of the transverse magnetic field. Modified…

Fluid Dynamics · Physics 2013-06-03 Masood Khan , Rabia Malik , Asia Anjum

We derived one-fluid equations based on a relativistic two-fluid approximation of e$^\pm$ pair plasma and electron-ion plasma to reveal the specific relativistic nature of their behavior. Assuming simple condition on the relativistic…

High Energy Astrophysical Phenomena · Physics 2009-08-11 Shinji Koide

The three-dimensional compressible magnetohydrodynamic (MHD) isentropic flow with zero magnetic diffusivity is studied. The vanishing magnetic diffusivity causes significant difficulties due to the loss of dissipation of the magnetic field.…

Analysis of PDEs · Mathematics 2011-08-30 Xiaoli Li , Ning Su , Dehua Wang

In the present paper, some elementary test cases in laminar flow with magnetic forcing terms are analyzed (Hartmann flow, Couette flow, Rayleigh flow); equations of the coupled problem are exposed and analytical solutions are derived in…

Classical Physics · Physics 2010-02-18 David Cebron , Jean-François Sigrist , Vincent Soyer , P. Ferrant

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

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

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

The relativistic hydrodynamics (RHD) equations can give rise to solutions which have shocks, contact discontinuities, and other sharp structures, which interact and evolve over time. Capturing these sharp waves effectively requires a mesh…

Numerical Analysis · Mathematics 2026-04-23 Sujoy Basak , Arpit Babbar , Harish Kumar , Praveen Chandrashekar

Ferromagnetic magnetohydrodynamics concerns the study of conducting fluids with intrinsic magnetisation under the influence of a magnetic field. It is a generalisation of the magnetohydrodynamical equations and takes into account the…

Analysis of PDEs · Mathematics 2024-12-09 Noah Vinod , Thanh Tran

The paradigm in which magnetic fields play a crucial role in launching/collimating outflows in many astrophysical objects continues to gain support. However, semi-analytical models including the effect of magnetic fields on the dynamics and…

High Energy Astrophysical Phenomena · Physics 2017-12-13 Chiara Ceccobello , Yuri Cavecchi , Martin H. M. Heemskerk , Sera Markoff , Peter Polko , David L. Meier

Imposing the Petrov-like boundary condition on the hypersurface at finite cutoff, we derive the hydrodynamic equation on the hypersurface from the bulk Einstein equation with electromagnetic field in the near horizon limit. We first get the…

High Energy Physics - Theory · Physics 2012-11-02 Cheng-Yong Zhang , Yi Ling , Chao Niu , Yu Tian , Xiao-Ning Wu

We present a method for general relativistic smoothed particle hydrodynamics (GRSPH), based on an entropy-conservative form of the general relativistic hydrodynamic equations for a perfect fluid. We aim to replace approximate treatments of…

Instrumentation and Methods for Astrophysics · Physics 2019-01-25 David Liptai , Daniel J. Price

A description is given of the algorithms implemented in the AstroBEAR adaptive mesh refinement code for ideal magnetohydrodynamics. The code provides several high resolution, shock capturing schemes which are constructed to maintain…

Astrophysics · Physics 2009-06-23 Andrew J. Cunningham , Adam Frank , Peggy Varniere , Sorin Mitran , Thomas W. Jones

We prove that smooth solutions of non-ideal (viscous and resistive) incompressible magnetohydrodynamic equations satisfy a stochastic law of flux conservation. This property involves an ensemble of surfaces obtained from a given, fixed…

Plasma Physics · Physics 2015-05-13 Gregory L. Eyink

Relativistic jets in active galactic nuclei, galactic microquasars, and gamma-ray bursts are widely considered to be magnetohydrodynamically driven by black hole accretion systems, although conversion mechanism from Poynting into particle…

High Energy Astrophysical Phenomena · Physics 2016-06-21 Kenji Toma , Fumio Takahara