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We describe a numerical algorithm to integrate the equations of radiation magnetohydrodynamics in multidimensions using Godunov methods. This algorithm solves the radiation moment equations in the mixed frame, without invoking any…

High Energy Astrophysical Phenomena · Physics 2012-03-05 Yan-Fei Jiang , James M. Stone , Shane W. Davis

Numerical simulation of multi-component flow systems characterized by the simultaneous presence of pressure-velocity coupling and pressure-density coupling dominated regions remains a significant challenge in computational fluid dynamics.…

Fluid Dynamics · Physics 2025-10-17 Xi Deng , Bin Xie , Omar K. Matar , Pierre Boivin

We review numerical methods for simulations of cosmic ray (CR) propagation on galactic and larger scales. We present the development of algorithms designed for phenomenological and self-consistent models of CR propagation in kinetic…

High Energy Astrophysical Phenomena · Physics 2021-06-17 M. Hanasz , A. Strong , P. Girichidis

In this article, we present a state-of-the-art algorithm for solving the relativistic viscous hydrodynamics equation with the QCD equation of state. The numerical method is based on the second-order Godunov method and has less numerical…

Nuclear Theory · Physics 2015-06-12 Yukinao Akamatsu , Shu-ichiro Inutsuka , Chiho Nonaka , Makoto Takamoto

The theory of diffusive particle acceleration explains the spectral properties of the cosmic rays below energies of approx. 10^6 GeV as produced at strong shocks in supernova remnants (SNR's). To supply the observed flux of cosmic rays, a…

Astrophysics · Physics 2007-05-23 U. D. J. Gieseler , T. W. Jones , Hyesung Kang

Diffusive shock acceleration is a prominent mechanism for producing energetic particles in space and in astrophysical systems. Such energetic particles have long been predicted to affect the hydrodynamic structure of the shock, in turn…

High Energy Astrophysical Phenomena · Physics 2020-12-16 Damiano Caprioli , Colby C. Haggerty , Pasquale Blasi

We study the change in cosmic-ray pressure, the change in cosmic-ray density, and the level of cosmic-ray induced heating via Alfven-wave damping when cosmic rays move from a hot ionized plasma to a cool cloud embedded in that plasma. The…

Astrophysics of Galaxies · Physics 2015-05-28 John E. Everett , Ellen G. Zweibel

Spectrum and chemical composition of cosmic rays accelerated in supernova remnants are studied on a basis of kinetic approach. The cosmic ray transport equation with the Bohm diffusion coefficient has been numerically solved…

Astrophysics · Physics 2008-02-03 E. G. Berezhko , G. F. Krymsky , V. K. Yelshin , L. T. Ksenofontov

Cosmic rays (CRs) are thought to play a dynamically important role in several key aspects of galaxy evolution, including the structure of the interstellar medium, the formation of galactic winds, and the non-thermal pressure support of…

Astrophysics of Galaxies · Physics 2019-11-19 Yohan Dubois , Benoît Commerçon , Alexandre Marcowith , Loann Brahimi

Using an improved version of the previously introduced CRASH (Cosmic Ray Acceleration SHock) code, we have calculated the time evolution of cosmic-ray (CR) modified quasi-parallel plane shocks for Bohm-like diffusion, including…

Astrophysics · Physics 2009-06-23 Hyesung Kang , T. W. Jones

Cosmic rays (CRs) have critical impacts in the multiphase interstellar medium (ISM), driving dynamical motions in low-density plasma and modifying the ionization state, temperature, and chemical composition of higher-density atomic and…

Astrophysics of Galaxies · Physics 2022-02-23 Christopher J. Bambic , Xue-Ning Bai , Eve C. Ostriker

A higher order Godunov method for the radiation subsystem of radiation hydrodynamics is presented. A key ingredient of the method is the direct coupling of stiff source term effects to the hyperbolic structure of the system of conservation…

Numerical Analysis · Mathematics 2009-10-09 Michael Sekora , James Stone

Cosmic rays (CRs) play an important role in many astrophysical systems. Acting on plasma scales to galactic environments, CRs are usually modeled as a fluid, using the CR energy density as the evolving quantity. This method comes with the…

High Energy Astrophysical Phenomena · Physics 2023-01-04 Matthias Weber , Timon Thomas , Christoph Pfrommer

Cosmological field-level inference requires differentiable forward models that solve the challenging dynamics of gas and dark matter under hydrodynamics and gravity. We propose a hybrid approach where gravitational forces are computed using…

Cosmology and Nongalactic Astrophysics · Physics 2025-10-31 Arne Thomsen , Tilman Tröster , François Lanusse

One of the fundamental differences of compressible fluid flows from incompressible fluid flows is the involvement of thermodynamics. This difference should be manifested in the design of numerical methods and seems often be neglected in…

Numerical Analysis · Mathematics 2017-05-24 Jiequan Li , Yue Wang

We present a numerical method to solve the equations of general relativistic hydrodynamics in a given external gravitational field. The method is based on a generalization of Roe's approximate Riemann solver for the non relativistic Euler…

Astrophysics · Physics 2007-05-23 Frits Eulderink , Garrelt Mellema

In the finite volume framework, a Lax-Wendrof type second-order flux solver for the compressible Navier-Stokes equations is proposed by utilizing a hyperbolic relaxation model. The flux solver is developed by applying the generalized…

Numerical Analysis · Mathematics 2025-03-03 Tuowei Chen , Zhifang Du

Cosmic ray (CR) hydrodynamics is a (re-)emerging field of high interest due to the importance of CRs for the dynamical evolution of the interstellar, the circumgalactic, and the intracluster medium. In these environments, CRs with GeV…

High Energy Astrophysical Phenomena · Physics 2021-11-03 Timon Thomas , Christoph Pfrommer

We have calculated the evolution of cosmic ray (CR) modified astrophysical shocks for a wide range of shock Mach numbers and shock speeds through numerical simulations of diffusive shock acceleration (DSA) in 1D quasi- parallel plane…

Astrophysics · Physics 2009-11-10 H. Kang , T. W. Jones

We describe a novel Godunov-type numerical method for solving the equations of resistive relativistic magnetohydrodynamics. In the proposed approach, the spatial components of both magnetic and electric fields are located at zone interfaces…

Computational Physics · Physics 2019-05-01 A. Mignone , G. Mattia , G. Bodo , L. Del Zanna