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In this paper, we consider a moving rigid solid immersed in a potential fluid. The fluid-solid system fills the whole two dimensional space and the fluid is assumed to be at rest at infinity. Our aim is to study the inverse problem,…

Analysis of PDEs · Mathematics 2015-05-19 Carlos Conca , Muslim Malik , Alexandre Munnier

Geometrical aspects of a perfect fluid spacetime are described in terms of different curvature tensors and $\eta$-Ricci and $\eta$-Einstein solitons in a perfect fluid spacetime are determined. Conditions for the Ricci soliton to be steady,…

Differential Geometry · Mathematics 2025-08-04 Adara M. Blaga

We prove the Benjamin and Lighthill conjecture for all two-dimensional steady water waves with an arbitrary vorticity distribution. We show that the flow force constant of an arbitrary smooth wave is bounded by the corresponding flow force…

Analysis of PDEs · Mathematics 2020-12-01 Evgeniy Lokharu

Einstein's equations of General Relativity form a highly nonlinear system, so most exact solutions rely on symmetry assumptions. Spherically symmetric spacetimes have been particularly important, providing a tractable yet physically rich…

General Relativity and Quantum Cosmology · Physics 2026-01-08 Salvador Mengual

Analyzing the spacetime for a static spherically distributed perfect fluid we show that the smooth matching of the interior and exterior metrics for a realistic source is possible only for the distances from the origin that exceeds the…

General Physics · Physics 2019-08-13 Merab Gogberashvili , Beka Modrekiladze

Exact solutions of a classical problem of a plane unsteady potential flow of an ideal incompressible fluid with a free boundary are presented. The fluid occupies a semi-infinite strip bounded by the free surface (from above) and (from the…

Fluid Dynamics · Physics 2021-08-13 Evgenii A. Karabut , Elena N. Zhuravleva , Nikolay M. Zubarev , Olga V. Zubareva

A criterion is presented and discussed to detect when a divergence-free perfect fluid energy tensor in the space-time describes an evolution in local thermal equilibrium. This criterion is applied to the class II Szafron-Szekeres perfect…

General Relativity and Quantum Cosmology · Physics 2007-05-23 Bartolomé Coll , Joan Josep Ferrando

The present paper is to deliberate the geometric composition of a perfect fluid spacetime with torse-forming vector field {\xi} in connection with conformal Ricci-Yamabe metric and conformal {\eta}-Ricci-Yamabe metric. Here we have…

Differential Geometry · Mathematics 2021-05-25 Soumendu Roy , Santu Dey , Arindam Bhattacharyya

Static spherically symmetric perfect fluid solutions are studied in metric $f(R)$ theories of gravity. We show that pressure and density do not uniquely determine $f(R)$ ie. given a matter distribution and an equation state, one cannot…

Astrophysics · Physics 2008-11-26 T. Multamaki , I. Vilja

We open the paper with introductory considerations describing the motivations of our long-term research plan targeting gravitomagnetism, illustrating the fluid-dynamics numerical test case selected for that purpose, that is, a perfect-gas…

In the present paper we analyze and discuss some mathematical aspects of the fluid-static configurations of a self-gravitating perfect gas enclosed in a spherical solid shell. The mathematical model we consider is based on the well-known…

We present a new formulation of non-dissipative relativistic spin hydrodynamics that incorporates spin degrees of freedom into the divergence-type theory framework. Due to the divergence-type structure, it is straightforward to enforce…

Nuclear Theory · Physics 2025-11-26 Nick Abboud , Lorenzo Gavassino , Rajeev Singh , Enrico Speranza

By a choice of new variables the pressure isotropy condition for spherically symmetric static perfect fluid spacetimes can be made a quadratic algebraic equation in one of the two functions appearing in it. Using the other variable as a…

General Relativity and Quantum Cosmology · Physics 2007-05-23 Gyula Fodor

The gravitational collapse of cylindrically distributed perfect fluid is studied. We assume the collapsing speed of fluid is very large and investigate such a situation by recently proposed high-speed approximation scheme. We show that if…

General Relativity and Quantum Cosmology · Physics 2009-11-10 Ken-ichi Nakao , Yoshiyuki Morisawa

In this paper, we study in detail a perfect fluid cosmological model with time-varying "constants" using dimensional analysis and the symmetry method. We examine the case of variable "constants" in detail without considering the perfect…

General Relativity and Quantum Cosmology · Physics 2009-12-30 José Antonio Belinchón , Indrajit Chakrabarty

We investigate the interior Einstein's equations in the case of a static, axially symmetric, perfect fluid source. We present a particular line element that is specially suitable for the investigation of this type of interior gravitational…

General Relativity and Quantum Cosmology · Physics 2022-03-29 Medeu Abishev , Farida Belissarova , Kuantay Boshkayev , Hernando Quevedo , Saken Toktarbay , Aizhan Mansurova , Aray Muratkhan

The equations governing the flow of a viscous incompressible fluid around a rigid body that performs a prescribed time-periodic motion with constant axes of translation and rotation are investigated. Under the assumption that the period and…

Analysis of PDEs · Mathematics 2019-12-12 Thomas Eiter , Mads Kyed

In this paper we assume that a perfect fluid is the source of the gravitational field while analyzing the solutions to the Einstein field equations.

General Relativity and Quantum Cosmology · Physics 2024-02-26 Krishnendu De , Uday Chand De , Ljubica Velimirovic

The present status of the shear-free fluid conjecture in general relativity is discussed: a review is given of recent partial proofs, a new and complete proof is given for the case of a linear equation of state, including a non-zero…

General Relativity and Quantum Cosmology · Physics 2016-09-27 Norbert Van den Bergh , Radu Slobodeanu

A relativistic fluid ball with an inhomogeneous static stratified matter configuration is considered. A model of an astrophysical object with this structure of matter is constructed.

General Relativity and Quantum Cosmology · Physics 2011-12-30 Alexandre M. Baranov , Alexander Yu. Osipov