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This work presents the Riemann solution for three-phase flow in porous media under the condition that oil viscosity exceeds that of water and gas. We classify all Riemann solution problems for scenarios where the left states $L$ lie along…

Analysis of PDEs · Mathematics 2025-06-12 Luis Fernando Lozano , Furtado Frederico , De Souza Aparecido , Marchesin Dan

Two new approaches to solving first-order quasilinear elliptic systems of PDEs in many dimensions are proposed. The first method is based on an analysis of multimode solutions expressible in terms of Riemann invariants, based on links…

Mathematical Physics · Physics 2014-10-01 A. M. Grundland , V. Lamothe

Observations of neutron stars (NSs) by the LIGO-Virgo and NICER collaborations have provided reasonably precise measurements of their various macroscopic properties. In this paper, we employ a Bayesian framework to combine them and place…

High Energy Astrophysical Phenomena · Physics 2021-05-26 Bhaskar Biswas , Prasanta Char , Rana Nandi , Sukanta Bose

The departure from ideal gas behavior is described by several known equations of state (EoS), developed from a combination of theoretical considerations and experimental correlations. In this work a different approach is proposed, in which…

Statistical Mechanics · Physics 2011-03-31 D. Giusti , V. Molinari , D. Mostacci

We derive a new class of exact solutions characterized by the Szekeres-Szafron metrics (of class I), admitting in general no isometries. The source is a fluid with viscosity but zero heat flux (adiabatic but irreversible evolution) whose…

General Relativity and Quantum Cosmology · Physics 2009-10-31 Roberto A. Sussman , Josep Triginer

Incompressible Euler flows in narrow domains, in which the horizontal length scale is much larger than other scales, play an important role in applications, and their leading-order behavior can be described by the hydrostatic Euler…

Analysis of PDEs · Mathematics 2023-01-26 Wang Shing Leung , Tak Kwong Wong , Chunjing Xie

Modern generative models hold great promise for accelerating diverse tasks involving the simulation of physical systems, but they must be adapted to the specific constraints of each domain. Significant progress has been made for…

Machine Learning · Statistics 2025-12-19 Louis Grenioux , Leonardo Galliano , Ludovic Berthier , Giulio Biroli , Marylou Gabrié

The ultra-relativistic Euler equations for an ideal gas are described in terms of the pressure $p$, the spatial part $\underline{u} \in \R^3$ of the dimensionless four-velocity and the particle density $n$. Radially symmetric solutions of…

Numerical Analysis · Mathematics 2020-02-05 Matthias Kunik , Hailiang Liu , Gerald Warnecke

This article presents a novel resolution to the problem of spline interpolation versus least-squares fitting on smooth Riemannian manifolds utilizing the method of gradient flows of networks. This approach represents a contribution to both…

Optimization and Control · Mathematics 2024-05-30 Chun-Chi Lin , The Dung Tran

The Generalized Riemann Problems (GRP) for nonlinear hyperbolic systems of balance laws in one space dimension are now well-known and can be formulated as follows: Given initial-data which are smooth on two sides of a discontinuity,…

Numerical Analysis · Mathematics 2013-03-13 Jianzhen Qian , Jiequan Li , Shuanghu Wang

Gravitational collapse of a spherically symmetric homogeneous perfect barotropic fluid with linear as well as polytropic type Equation of State (EoS) has been investigated in the framework of a linear model of $f(R,T)$ gravity. This…

General Relativity and Quantum Cosmology · Physics 2020-05-06 Karim Mosani , Gauranga C. Samanta

Within OpenFOAM, we develop a pressure-based solver for the Euler equations written in conservative form using density, momentum, and total energy as variables. Under simplifying assumptions, these equations are used to describe…

Fluid Dynamics · Physics 2023-02-10 Michele Girfoglio , Annalisa Quaini , Gianluigi Rozza

Cosmological solutions of Einstein's equation for fluids with heat flow in a generalized Robertson-Walker metric are obtained, generalizing the results of Bergmann.

General Relativity and Quantum Cosmology · Physics 2019-11-19 Abhik Kumar Sanyal , Dipankar Ray

The Harten-Lax-van Leer with contact (HLLC) scheme is known to be plagued by various forms of numerical shock instabilities. In this paper, we propose a new framework for developing shock stable, contact and shear preserving approximate…

Computational Physics · Physics 2018-03-14 Simon Sangeeth , J. C Mandal

The staid subject of exact static spherically symmetric perfect fluid solutions of Einstein's equations has been reinvigorated in the last decade. We now have several solution generating techniques which give rise to new exact solutions.…

General Relativity and Quantum Cosmology · Physics 2008-11-26 Kayll Lake

The temperature of the interstellar medium (ISM) is governed by several physical process, among which radiative cooling, external UV/cosmic ray heating, and the mechanical work by compression and expansion. In regimes where the dynamical…

Astrophysics of Galaxies · Physics 2024-01-19 Yueh-Ning Lee

The paper investigates the use of low-diffusion (contact-discontinuity-resolving [Liou M.S.: {\em J. Comp. Phys.} {\bf 160} (2000) 623--648]) approximate Riemann solvers for the convective part of the Reynolds-averaged Navier-Stokes…

Computational Physics · Physics 2016-07-01 N. Ben Nasr , G. A. Gerolymos , I. Vallet

In this paper, we present an approach to solving the Riemann problem in one-dimensional relativistic hydrodynamics, where the most computationally expensive steps of the exact solver are replaced by compact, highly specialized neural…

General Relativity and Quantum Cosmology · Physics 2025-05-27 Carlo Musolino

Following a solution generating technique introduced recently by one of us, we transform the Einstein static Universe into a two - fold infinity class of physically acceptable exact perfect fluid solutions of Einstein's equations. Whereas…

General Relativity and Quantum Cosmology · Physics 2008-11-26 Cédric Grenon , Pascal J. Elahi , Kayll Lake

We study the global existence of a unique strong solution and its large-time behavior of a two-phase fluid system consisting of the compressible isothermal Euler equations coupled with compressible isentropic Navier-Stokes equations through…

Analysis of PDEs · Mathematics 2016-07-04 Young-Pil Choi