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We derive a consistent set of moments equations for CR-magnetohydrodynamics, assuming a gyrotropic distribution function (DF). Unlike previous efforts we derive a closure, akin to the M1 closure in radiation hydrodynamics (RHD), that is…

High Energy Astrophysical Phenomena · Physics 2022-03-18 Philip F. Hopkins , Jonathan Squire , Iryna S. Butsky

In this work, a steady discrete unified gas kinetic scheme (SDUGKS) is proposed to solve the steady radiative transfer equation (RTE), which is an improvement of the original SDUGKS [X. F. Zhou et al., J. Comput. Phys. 423, 109767 (2020)].…

Computational Physics · Physics 2022-11-22 Xinliang Song , Yue Zhang , Xiafeng Zhou , Chuang Zhang , Zhaoli Guo

The ideal MHD equations are a central model in astrophysics, and their solution relies upon stable numerical schemes. We present an implementation of a new method, which possesses excellent stability properties. Numerical tests demonstrate…

Instrumentation and Methods for Astrophysics · Physics 2011-04-28 Knut Waagan , Christoph Federrath , Christian Klingenberg

Ultrafast electronic dynamics in solids lies at the core of modern condensed matter and materials physics. To build up a practical ab initio method for studying solids under photoexcitation, we develop a momentum-resolved real-time time…

Materials Science · Physics 2018-10-17 Chao Lian , Shi-Qi Hu , Meng-Xue Guan , Sheng Meng

We introduce new adaptive artificial anti-diffusion (AAAD) methods for one- and two-dimensional hyperbolic systems of conservation laws. The key idea is to reduce the amount of numerical dissipation present in a given numerical method by…

Numerical Analysis · Mathematics 2026-05-18 Shaoshuai Chu , Igor Kliakhandler , Alexander Kurganov

"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 present a fast adaptive method for the evaluation of heat potentials, which plays a key role in the integral equation approach for the solution of the heat equation, especially in a non-stationary domain. The algorithm utilizes a…

Numerical Analysis · Mathematics 2024-12-06 Chengyue Song , Jun Wang

Recent three-dimensional radiative hydrodynamics simulations of protoplanetary disks report disparate disk behaviors, and these differences involve the importance of convection to disk cooling, the dependence of disk cooling on metallicity,…

Astrophysics · Physics 2009-06-23 Aaron C. Boley , Richard H. Durisen , Aake Nordlund , Jesse Lord

This work deals with the numerical solution of the monodomain and bidomain models of electrical activity of myocardial tissue. The bidomain model is a system consisting of a possibly degenerate parabolic PDE coupled with an elliptic PDE for…

Numerical Analysis · Mathematics 2008-07-03 Mostafa Bendahmane , Raimund Bürger , Ricardo Ruiz Baier

Astrophysical plasmas are subject to a tight connection between magnetic fields and the diffusion of particles, which leads to an anisotropic transport of energy. Under the fluid assumption, this effect can be reduced to an…

Astrophysics of Galaxies · Physics 2016-01-13 Yohan Dubois , Benoît Commerçon

We have written and tested a new general relativistic magnetohydrodynamics (GRMHD) code, capable of evolving MHD fluids in dynamical spacetimes with adaptive-mesh refinement (AMR). Our code solves the Einstein-Maxwell-MHD system of coupled…

High Energy Astrophysical Phenomena · Physics 2010-10-27 Zachariah B. Etienne , Yuk Tung Liu , Stuart L. Shapiro

We adopt a two-moment formalism, together with a reference-metric approach, to express the equations of relativistic radiation hydrodynamics in a form that is well-suited for numerical implementations in curvilinear coordinates. We…

General Relativity and Quantum Cosmology · Physics 2020-11-11 Thomas W. Baumgarte , Stuart L. Shapiro

We present a new numerical method for the isometric embedding of 2-geometries specified by their 2-metrics in three dimensional Euclidean space. Our approach is to directly solve the fundamental embedding equation supplemented by six…

General Relativity and Quantum Cosmology · Physics 2015-06-23 Wolfgang Tichy , Jonathan R. McDonald , Warner A. Miller

Generalized Hydrodynamics (GHD) has recently been devised as a method to solve the dynamics of integrable quantum many-body systems beyond the mean-field approximation. In its original form, a major limitation is the inability to predict…

We describe the remapped particle-mesh method, a new mass-conserving method for solving the density equation which is suitable for combining with semi-Lagrangian methods for compressible flow applied to numerical weather prediction. In…

Atmospheric and Oceanic Physics · Physics 2009-11-13 Colin J. Cotter , Jason Frank , Sebastian Reich

In this paper the projection hybrid FV/FE method presented in Busto et al. 2014 is extended to account for species transport equations. Furthermore, turbulent regimes are also considered thanks to the $k-\varepsilon$ model. Regarding the…

Numerical Analysis · Mathematics 2023-01-23 Saray Busto , Jose Luis Ferrin , Eleuterio F. Toro , Maria Elena Vazquez-Cendon

The smoothed particle hydrodynamics (SPH) method has been increasingly used to study fluid problems in recent years; but its computational cost can be high if high resolution is required. In this study, an adaptive resolution method based…

Computational Physics · Physics 2019-01-23 Xiufeng Yang , Song-Charng Kong

This is the second paper in a series in which we develop machine learning (ML) moment closure models for the radiative transfer equation (RTE). In our previous work \cite{huang2021gradient}, we proposed an approach to directly learn the…

Numerical Analysis · Mathematics 2021-06-01 Juntao Huang , Yingda Cheng , Andrew J. Christlieb , Luke F. Roberts , Wen-An Yong

A new computationally efficient method has been introduced to treat self-gravity in mesh based hydrodynamical simulations. It is applied simply by slightly modifying the Poisson equation into an inhomogeneous wave equation. This roughly…

Instrumentation and Methods for Astrophysics · Physics 2016-04-20 Ryosuke Hirai , Hiroki Nagakura , Hirotada Okawa , Kotaro Fujisawa

We present the implementation of an implicit-explicit (IMEX) Runge-Kutta numerical scheme for general relativistic hydrodynamics coupled to an optically thick radiation field in two existing GR-hydrodynamics codes. We argue that the…

High Energy Astrophysical Phenomena · Physics 2015-06-05 Constanze Roedig , Olindo Zanotti , Daniela Alic
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