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We present and explore a new shock-capturing particle hydrodynamics approach. Our starting point is a commonly used discretization of smoothed particle hydrodynamics. We enhance this discretization with Roe's approximate Riemann solver, we…

Fluid Dynamics · Physics 2025-12-24 S. Rosswog

A numerical procedure was developed for solving equations for compressible granular multiphase flows in which the particle volume fraction can range dynamically from very dilute to very dense. The procedure uses a low-dissipation and…

Computational Physics · Physics 2014-10-20 Ryan W. Houim , Elaine S. Oran

Corrugation instabilities occurring for solutions of the Riemann problem in relativistic hydrodynamics in which the fluid moves with a non-zero velocity tangent to the initial discontinuity are studied numerically. We perform simulations…

Mathematical Physics · Physics 2015-05-27 Patryk Mach

In this paper, we develop a new method for magnetohydrodynamics (MHD) using smoothed particle hydrodynamics (SPH). To describe MHD shocks accurately, the Godunov method is applied to SPH instead of artificial dissipation terms. In the…

Astrophysics of Galaxies · Physics 2015-05-28 Kazunari Iwasaki , Shu-ichiro Inutsuka

The paper presents a new approach of stability evaluation of the approximate Riemann solvers based on the direct Lyapunov method. The present methodology offers a detailed understanding of the origins of numerical shock instability in the…

Numerical Analysis · Mathematics 2024-03-27 Aishwarjya Gogoi , Jadav Chandra Mandal , Amitabh Saraf

We introduce an adaptive viscosity regularization approach for the numerical solution of systems of nonlinear conservation laws with shock waves. The approach seeks to solve a sequence of regularized problems consisting of the system of…

Fluid Dynamics · Physics 2023-09-19 Ngoc Cuong Nguyen , Jordi Vila-Perez , Jaime Peraire

The idea of this work is to compare a new positive and entropy stable approximate Riemann solver by Francois Bouchut with a state-of the-art algorithm for astrophysical fluid dynamics. We implemented the new Riemann solver into an…

Astrophysics · Physics 2009-11-13 Christian Klingenberg , Wolfram Schmidt , Knut Waagan

We propose a new method to solve the relativistic hydrodynamic equations based on implicit Runge-Kutta methods with a locally optimized fixed-point iterative solver. For numerical demonstration, we implement our idea for ideal hydrodynamics…

Nuclear Theory · Physics 2024-04-16 Nathan Touroux , Masakiyo Kitazawa , Koichi Murase , Marlene Nahrgang

We have built a code to obtain the exact solutions of Riemann problems in ideal magnetohydrodynamics (MHD) for an arbitrary initial condition. The code can handle not only regular waves but also switch-on/off rarefactions and all types of…

High Energy Astrophysical Phenomena · Physics 2019-02-20 Kazuya Takahashi , Shoichi Yamada

Our contribution concerns with the numerical solution of the 3D general relativistic hydrodynamical system of equations within the framework of the 3+1 formalism. We summarize the theoretical ingredients which are necessary in order to…

Astrophysics · Physics 2007-05-23 J. M. Ibanez , M. A. Aloy , J. A. Font , J. M. Marti , J. A. Miralles , J. A. Pons

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

We present results based on an implementation of the Godunov Smoothed Particle Hydrodynamics (GSPH), originally developed by Inutsuka (2002), in the GADGET-3 hydrodynamic code. We first review the derivation of the GSPH discretization of…

Instrumentation and Methods for Astrophysics · Physics 2015-05-28 Giuseppe Murante , Stefano Borgani , Riccardo Brunino , Suneg-Hoon Cha

Godunov-type methods, which obtain numerical fluxes through local Riemann problems at cell interfaces, are among the most fundamental and widely used numerical methods in computational fluid dynamics. Exact Riemann solvers faithfully solve…

Computational Physics · Physics 2026-04-01 Yucheng Zhang , Chayanon Wichitrnithed , Shukai Cai , Sourav Dutta , Kyle Mandli , Clint Dawson

This is the first of two papers examining the critical collapse of spherically symmetric perfect fluids with the equation of state P = (Gamma -1)rho. Here we present the equations of motion and describe a computer code capable of simulating…

General Relativity and Quantum Cosmology · Physics 2014-11-17 David W. Neilsen , Matthew W. Choptuik

The characteristic formulation of the relativistic hydrodynamic equations (Donat et al 1998 J. Comput. Phys. 146 58), which has been implemented in many relativistic hydro-codes that make use of Godunov-type methods, has to be slightly…

Solar and Stellar Astrophysics · Physics 2012-11-27 J. M. Ibáñez , I. Cordero-Carrión , J. A. Miralles

We present an exact solution of the relativistic Boltzmann equation for a system undergoing boost-invariant longitudinal and azimuthally symmetric transverse flow ("Gubser flow"). The resulting exact non-equilibrium dynamics is compared to…

High Energy Physics - Phenomenology · Physics 2014-11-17 Gabriel S. Denicol , Ulrich W. Heinz , Mauricio Martinez , Jorge Noronha , Michael Strickland

We report on our numerical implementation of fully relativistic hydrodynamics coupled to Einstein's field equations in three spatial dimensions. We briefly review several steps in our code development, including our recasting of Einstein's…

General Relativity and Quantum Cosmology · Physics 2009-10-31 T. W. Baumgarte , S. A. Hughes , L. Rezzolla , S. L. Shapiro , M. Shibata

A Riemann problem with prescribed initial conditions will produce one of three possible wave patterns corresponding to the propagation of the different discontinuities that will be produced once the system is allowed to relax. In general,…

General Relativity and Quantum Cosmology · Physics 2017-05-17 L. Rezzolla , O. Zanotti

We review recent interest in the relativistic Riemann problem as a method for generating a non-equilibrium steady state. In the version of the problem under con- sideration, the initial conditions consist of a planar interface between two…

High Energy Physics - Theory · Physics 2016-11-23 Michael Spillane , Christopher P. Herzog

We discuss the procedure for the exact solution of the Riemann problem in special relativistic magnetohydrodynamics (MHD). We consider both initial states leading to a set of only three waves analogous to the ones in relativistic…

General Relativity and Quantum Cosmology · Physics 2009-11-11 B. Giacomazzo , L. Rezzolla