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Many recent numerical studies have argued that cosmic rays (CRs) from supernovae (SNe) or active galactic nuclei (AGN) could play a crucial role in galaxy formation, in particular by establishing a CR-pressure dominated circum-galactic…

Astrophysics of Galaxies · Physics 2023-08-29 Philip F. Hopkins , Iryna S. Butsky , Suoqing Ji , Dusan Keres

In this paper we present a new family of approximate Riemann solvers for the numerical approximation of solutions of hyperbolic conservation laws. They are approximate, also referred to as incomplete, in the sense that the solvers avoid…

Numerical Analysis · Mathematics 2017-10-10 Birte Schmidtmann , Mariia Astrakhantceva , Manuel Torrilhon

A new multidimensional simulation code for relativistic two-fluid electrodynamics (RTFED) is described. The basic equations consist of the full set of Maxwell's equations coupled with relativistic hydrodynamic equations for separate two…

High Energy Astrophysical Phenomena · Physics 2016-11-09 Takanobu Amano

Resistive relativistic magnetohydrodynamic (RRMHD) simulations are applied to investigate the system evolution of relativistic magnetic reconnection. A time-split Harten--Lan--van Leer method is employed. Under a localized resistivity, the…

High Energy Astrophysical Phenomena · Physics 2010-06-07 Seiji Zenitani , Michael Hesse , Alex Klimas

We design a conservative finite difference scheme for ideal magnetohydrodynamic simulations that attains high-order accuracy, shock-capturing, and divergence-free condition of the magnetic field. The scheme interpolates pointwise physical…

Instrumentation and Methods for Astrophysics · Physics 2019-06-05 Takashi Minoshima , Takahiro Miyoshi , Yosuke Matsumoto

We have built a code to numerically solve the Riemann problem in ideal magnetohydrodynamics (MHD) for an arbitrary initial condition to investigate a variety of solutions more thoroughly. The code can handle not only regular solutions, in…

High Energy Astrophysical Phenomena · Physics 2015-06-11 Kazuya Takahashi , Shoichi Yamada

Many systems of current interest in relativistic astrophysics require a knowledge of radiative transfer in a magnetized gas flowing in a strongly-curved, dynamical spacetime. Such systems include coalescing compact binaries containing…

Astrophysics · Physics 2008-11-26 Brian D. Farris , Tsz Ka Li , Yuk Tung Liu , Stuart L. Shapiro

Within the context of a viscoresistive magnetohydrodynamic (MHD) model with anisotropic heat transport and cross-field mass diffusion, we introduce novel three-term representations for the magnetic field (background vacuum field, field line…

Plasma Physics · Physics 2019-10-15 Nikita Nikulsin , Matthias Hoelzl , Alessandro Zocco , Karl Lackner , Sibylle Günter

In this paper, we prove the energy conservation for the weak solutions to the three-dimensional equations of compressible magnetohydrodynamic flows (MHD) under certain conditions only about density and velocity. This work is inspired by the…

Analysis of PDEs · Mathematics 2019-06-26 Tingsheng Wang , Xinhua Zhao , Yingshan Chen , Mei Zhang

In Lagrangian coordinates, the local well-posedness of low regularity solutions is established for an ideal incompressible magnetohydrodynamic (MHD) system subject to a homogeneous background magnetic field. First, the MHD system is…

Analysis of PDEs · Mathematics 2026-02-05 Huali Zhang

The shallow water equations are numerically solved to simulate free surface flows. The convective flux terms in the shallow water equations need to be discretized using a Riemann solver to capture shocks and discontinuity for certain flow…

Fluid Dynamics · Physics 2024-10-10 D. Satyaprasad , Soumendra Nath Kuiry , S. Sundar

A new code and methodology are introduced for solving the general relativistic magnetohydrodynamic (GRMHD) equations in fixed background spacetimes using time-explicit, finite-volume discretization. The code has options for solving the…

Astrophysics · Physics 2009-11-13 Peter Anninos , P. Chris Fragile , Jay D. Salmonson

We present a new numerical code, X-ECHO, for general relativistic magnetohydrodynamics (GRMHD) in dynamical spacetimes. This is aimed at studying astrophysical situations where strong gravity and magnetic fields are both supposed to play an…

Instrumentation and Methods for Astrophysics · Physics 2015-05-20 N. Bucciantini , L. Del Zanna

We have generalised the exact solution of the Riemann problem in special relativistic hydrodynamics for arbitrary tangential flow velocities. The solution is obtained by solving the jump conditions across shocks plus an ordinary…

Astrophysics · Physics 2007-05-23 J. Pons , J. Ma. Marti , E. Muller

In this era of precision cosmology, a detailed physical understanding on the evolution of cosmic baryons is required. Cosmic magnetic fields, though still poorly understood, may represent an important component in the global cosmic energy…

Astrophysics · Physics 2015-06-24 Shengtai Li , Hui Li , Renyue Cen

The characteristic decomposition for GRMHD is not known in a form useful for current numerical simulations. This prevents us from using the most accurate known computational methods, such as full-wave Riemann solvers. In this paper, we…

General Relativity and Quantum Cosmology · Physics 2025-11-19 Saul A. Teukolsky

We introduce CRK-HACC, an extension of the Hardware/Hybrid Accelerated Cosmology Code (HACC), to resolve gas hydrodynamics in large-scale structure formation simulations of the universe. The new framework couples the HACC gravitational…

Cosmology and Nongalactic Astrophysics · Physics 2023-02-01 Nicholas Frontiere , J. D. Emberson , Michael Buehlmann , Joseph Adamo , Salman Habib , Katrin Heitmann , Claude-André Faucher-Giguère

In shock precursors populated by accelerated cosmic rays (CR), the CR return current instability is believed to significantly enhance the pre-shock perturbations of magnetic field. We have obtained fully-nonlinear exact ideal MHD solutions…

Astrophysics of Galaxies · Physics 2016-10-11 M. A. Malkov , R. Z. Sagdeev , P. H. Diamond

We present a second-order upwind numerical scheme for equations of relativistic hydrodynamics with a source term. A new non-linear Riemann solver is constructed. Solution of a Riemann problem on a cells boundary is based on exact relations…

Astrophysics · Physics 2008-03-20 Pavlo V. Tytarenko , Iurii A. Karpenko , Yury M. Sinyukov

Relativistic magnetic reconnection is thought to power various multi-wavelength emission signatures from neutron stars and black holes. Relativistic resistive magnetohydrodynamics (RRMHD) offers the simplest model of reconnection. However,…

High Energy Astrophysical Phenomena · Physics 2026-01-07 B. Ripperda , M. P. Grehan , A. Moran , S. Selvi , L. Sironi , A. Philippov , A. Bransgrove , O. Porth