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Radiative transfer and radiation hydrodynamics use the relativistic Boltzmann equation to describe the kinetics of photons. It is difficult to solve the six-dimensional time-dependent transfer equation unless the problem is highly symmetric…

Instrumentation and Methods for Astrophysics · Physics 2011-02-09 Chi-kwan Chan

We consider multi-dimensional junction problems for first- and second-order pde with Kirchoff-type Neumann boundary conditions and we show that their generalized viscosity solutions are unique. It follows that any viscosity-type…

Analysis of PDEs · Mathematics 2019-11-13 Pierre-Louis Lions , Panagiotis Souganidis

We consider the two dimensional unsteady Prandtl system. For a special class of outer Euler flows and solutions of the Prandtl system, the trace of the tangential derivative of the tangential velocity along the transversal axis solves a…

Analysis of PDEs · Mathematics 2022-04-08 Charles Collot , Tej-Eddine Ghoul , Slim Ibrahim , Nader Masmoudi

We analyze the cosmic-ray magnetohydrodynamic (CR MHD) equations to improve the numerical simulations. We propose to solve them in the fully conservation form, which is equivalent to the conventional CR MHD equations. In the fully…

High Energy Astrophysical Phenomena · Physics 2016-10-07 Yuki Kudoh , Tomoyuki Hanawa

We describe the details of 3+1 dimensional relativistic hydrodynamic code for the simulations of quark-gluon/hadron matter expansion in ultra-relativistic heavy ion collisions. The code solves the equations of relativistic viscous…

Nuclear Theory · Physics 2014-09-08 Iu. Karpenko , P. Huovinen , M. Bleicher

A collection of arbitrarily-shaped solid objects, each moving at a constant speed, can be used to mix or stir ideal fluid, and can give rise to interesting flow patterns. Assuming these systems of fluid stirrers are two-dimensional, the…

Complex Variables · Mathematics 2017-01-03 Mohamed M. S. Nasser , Christopher C. Green

We generalize the previously obtained Kru\v{z}kov-type uniqueness result for the initial-boundary value problem for the chemical flood conservation law system to the case of an almost arbitrary flow function, not restricted by the S-shaped…

Analysis of PDEs · Mathematics 2025-12-09 Yulia Petrova , Nikita Rastegaev

We describe the special relativistic extension of the CRONOS code, which has been used for studies of gamma-ray binaries in recent years. The code was designed to be easily adaptable, allowing the user to easily change existing…

High Energy Astrophysical Phenomena · Physics 2021-09-29 David Huber , Ralf Kissmann

We provide the set of equations for non-relativistic fluid dynamics on arbitrary, possibly time-dependent spaces, in general coordinates. These equations are fully covariant under either local Galilean or local Carrollian transformations,…

High Energy Physics - Theory · Physics 2018-07-18 Luca Ciambelli , Charles Marteau , Anastasios C. Petkou , P. Marios Petropoulos , Konstantinos Siampos

We use a connection between relativistic hydrodynamics and scalar field theory to generate exact analytic solutions describing non-stationary inhomogeneous flows of the perfect fluid with one-parametric equation of state (EOS) $p =…

Mathematical Physics · Physics 2008-12-19 Maxim S. Borshch , Valery I. Zhdanov

Porosity-based models are a viable alternative to classical two-dimensional (2-d) Shallow water Equations (SWE) when the interaction of shallow flows with obstacles is modelled. The exact solution of the Single Porosity (SP) Riemann…

Fluid Dynamics · Physics 2023-07-18 Giada Varra , Renata Della Morte , Luigi Cimorelli , Luca Cozzolino

We develop a combined hydro-kinetic approach which incorporates a hydrodynamical expansion of the systems formed in \textit{A}+\textit{A} collisions and their dynamical decoupling described by escape probabilities. The method corresponds to…

Nuclear Theory · Physics 2008-11-26 S. V. Akkelin , Y. Hama , Iu. A. Karpenko , Yu. M. Sinyukov

The relativistic full Euler equations for a Chaplygin gas are studied. The Riemann problem is solved constructively. There are two kinds of Riemann solutions, in which one consists of three contact discontinuities and the other involves a…

Analysis of PDEs · Mathematics 2017-09-26 Zhiqiang Shao

The study of fluids has been a topic of intense research for several hundred years. Over the years, this has further increased due to improved computational facility, which makes it easy to numerically simulate the fluid dynamics, which was…

Fluid Dynamics · Physics 2021-03-05 Soumen Roy

In this paper, the Riemann problem for the pressureless Euler equations with a discontinuous source term is considered. The delta shock wave solution is obtained by combining the generalized Rankine-Hugoniot conditions together with the…

Analysis of PDEs · Mathematics 2017-12-13 Qingling Zhang

In this paper, we have solved 1D special relativistic hydrodynamical equations using different numerical method in computational gas dynamics. The numerical solutions of these equations for smooth wave cases give better solution when we use…

General Relativity and Quantum Cosmology · Physics 2007-05-23 Orhan Donmez

A well-known unsolved problem (in the classical theory of fluid mechanics) is to identify a set of initial velocities, which may depend on the viscosity, the body forces and possibly the boundary of the fluid that will allow global in time…

Mathematical Physics · Physics 2007-05-23 Tepper L Gill , Woodford W. Zachary

An exact solution to the lock-exchange problem, which is a two-layer analogue of the classical dam-break problem, is obtained in the shallow-water (SW) approximation for two immiscible fluids with slightly different densities. The problem…

Fluid Dynamics · Physics 2022-09-30 Gerasimos Politis , Jānis Priede

For the first time the exact vortex solution of the Cauchy problem in unbounded space is obtained for the three-dimensional Euler-Helmholtz (EH) equation in the case of a nonzero-divergence velocity field for an ideal compressible medium.…

General Physics · Physics 2019-12-10 Sergey G. Chefranov , Artem S. Chefranov

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