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200 papers

Starting with a brief introduction into the basics of relativistic fluid dynamics, I discuss our current knowledge of a relativistic theory of fluid dynamics in the presence of (mostly shear) viscosity. Derivations based on the generalized…

High Energy Physics - Phenomenology · Physics 2010-03-02 Paul Romatschke

We use multi-frequency radiation hydrodynamics (rad-HD) to simulate radiative acceleration of a spherically symmetric stellar wind. We demonstrate the rad-HD capabilities of Athena++ for a series of test problems with multi-group radiation…

High Energy Astrophysical Phenomena · Physics 2019-11-22 Sergei Dyda , Christopher S. Reynolds , Yan-Fei Jiang

Context: Thermal conductivity provides important contributions to the energy evolution of the upper solar atmosphere, behaving as a non-linear concentration-dependent diffusion equation. Recently, different methods have been offered as…

Solar and Stellar Astrophysics · Physics 2024-12-11 George Cherry , Boris Gudiksen , Mikolaj Szydlarski

Radiative shocks are found in various astrophysical objects and particularly at different stages of stellar evolution. Studying radiative shocks, their topology, and thermodynamical properties is therefore a starting point to understanding…

Solar and Stellar Astrophysics · Physics 2009-11-13 Matthias González , Edouard Audit , Chantal Stehlé

An attempt is made to review the heat transfer and the related problems encountered in the simulation of single crystal growth. The peculiarities of conductive, convective and radiative heat transfer in the different melt, solution, and…

Fluid Dynamics · Physics 2014-10-08 Alexander I. Zhmakin

We conduct a numerical study of relativistic viscous fluid dynamics in the Density Frame for one-dimensional fluid flows. The Density Frame is a formulation of relativistic viscous hydrodynamics that is first-order in time, requires no…

We present a numerical implementation of radiative transfer based on an explicitly photon-conserving advection scheme, where radiative fluxes over the cell interfaces of a structured or unstructured mesh are calculated with a second-order…

Cosmology and Nongalactic Astrophysics · Physics 2015-05-20 Margarita Petkova , Volker Springel

The incorporation of radiative transfer effects into cosmological hydrodynamical simulations is essential for understanding how the intergalactic medium (IGM) makes the transition from a neutral medium to one that is almost fully ionized.…

Astrophysics · Physics 2009-11-06 Aaron Sokasian , Tom Abel , Lars E. Hernquist

In this paper we present a characteristic method for solving the transfer equation in differentially moving media in a curved spacetime. The method is completely general, but its capabilities are exploited at best in presence of symmetries,…

Astrophysics · Physics 2009-10-28 Silvia Zane , Roberto Turolla , Luciano Nobili , Myris Erna

Radiation interacts with matter via exchange of energy and momentum. When matter is moving with a relativistic velocity or when the background spacetime is strongly curved, rigorous relativistic treatment of hydrodynamics and radiative…

Astrophysics · Physics 2009-11-11 Myeong-Gu Park

A new method for the formal solution of the 2D radiative transfer equation in axial symmetry in the presence of arbitrary velocity fields is presented. The combination of long and short characteristics methods is used to solve the radiative…

Astrophysics · Physics 2016-08-16 D. Korčáková , J. Kubát

We present a ray-tracing technique for radiative transfer modeling of complex three-dimensional (3D) structures which include dense regions of high optical depth like in dense molecular clouds, circumstellar disks, envelopes of evolved…

Astrophysics · Physics 2009-11-11 J. Steinacker , A. Bacmann , Th. Henning

We have developed a time-dependent, multi-energy-group, and multi-angle (S$_n$) Boltzmann transport scheme for radiation hydrodynamics simulations, in one and two spatial dimensions. The implicit transport is coupled to both 1D…

Astrophysics · Physics 2009-11-10 Eli Livne , Adam Burrows , Rolf Walder , Itamar Lichtenstadt , Todd A. Thompson

We present a new approach to numerically model continuum radiative transfer based on the Optically Thin Variable Eddington Tensor (OTVET) approximation. Our method insures the exact conservation of the photon number and flux (in the…

Astrophysics · Physics 2009-11-06 Nickolay Y. Gnedin , Tom Abel

We present examples of validating components of an astrophysical simulation code. Problems of stellar astrophysics are multi-dimensional and involve physics acting on large ranges of length and time scales that are impossible to include in…

Solar and Stellar Astrophysics · Physics 2018-09-10 A. C. Calder , D. M. Townsley

This study investigates the heat transfer in a simple pure fluid whose temperature is slightly above its critical temperature. We propose a efficient numerical method to predict the heat transfer in such fluids when the gravity can be…

Fluid Dynamics · Physics 2016-01-26 Vadim Nikolayev , A Dejoan , Y. Garrabos , D Beysens

We present a new method for the numerical solution of the radiative-transfer equation (RTE) in multidimensional scenarios commonly encountered in computational astrophysics. The method is based on the direct solution of the Boltzmann…

Computational Physics · Physics 2020-10-06 L. R. Weih , A. Gabbana , D. Simeoni , L. Rezzolla , S. Succi , R. Tripiccione

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

We present results from self-consistent 3D numerical simulations of cosmic structure formation with a multi-frequency radiative transfer scheme and non-equilibrium molecular chemistry of 13 primordial species (e-, H, H+, H-, He, He+, He++,…

Cosmology and Nongalactic Astrophysics · Physics 2015-05-30 Margarita Petkova , Umberto Maio

We analyze the mixed frame equations of radiation hydrodynamics under the approximations of flux-limited diffusion and a thermal radiation field, and derive the minimal set of evolution equations that includes all terms that are of leading…

Astrophysics · Physics 2009-11-11 Mark R. Krumholz , Richard I. Klein , Christopher F. McKee , John Bolstad