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The properties of a transformation previously considered for generating new perfect-fluid solutions from known ones are further investigated. It is assumed that the four-velocity of the fluid is parallel to the stationary Killing field, and…

General Relativity and Quantum Cosmology · Physics 2009-10-30 Istvan Racz , Jozsef Zsigrai

Short review of the Weyl geometry is given. To describe the phenomenological particle creation we suggest the modified perfect fluid model taking into account the back reaction on the geometry of both the already created particles and the…

General Relativity and Quantum Cosmology · Physics 2024-01-15 Victor Aleksandrovich Berezin , Vyacheslav Ivanovich Dokuchaev

We analyze the interpretation of the spherically symmetric perfect fluid solutions that admit a flat synchronization orthogonal to the fluid flow as a thermodynamic perfect fluid in local thermal equilibrium. The ideal gas sonic condition…

General Relativity and Quantum Cosmology · Physics 2022-06-09 Salvador Mengual , Joan Josep Ferrando

We review the canonical theory for perfect fluids, in Eulerian and Lagrangian formulations. The theory is related to a description of extended structures in higher dimensions. Internal symmetry and supersymmetry degrees of freedom are…

High Energy Physics - Phenomenology · Physics 2009-11-10 R. Jackiw , V. P. Nair , S. -Y. Pi , A. P. Polychronakos

The perfect fluid solutions admitting a group G$_3$ of isometries acting on orbits S$_2$ whose curvature has a gradient which is tangent to the fluid flow (T-models) are studied from a thermodynamic approach. All the admissible…

General Relativity and Quantum Cosmology · Physics 2021-07-23 Joan Josep Ferrando , Salvador Mengual

This paper introduces an accelerated power series solution for Tolman-Oppenheimer-Volkoff (TOV) equation, which represents the relativistic polytropic fluid spheres. We constructed a recurrence relation for the series coefficients in the…

Solar and Stellar Astrophysics · Physics 2014-06-06 Mohamed Nouh , Abdelnaby Saad

Via a straightforward integration of the Einstein equations with cosmological constant, all static circularly symmetric perfect fluid 2+1 solutions are derived. The structural functions of the metric depend on the energy density, which…

General Relativity and Quantum Cosmology · Physics 2009-11-07 Alberto A. Garcia , Cuauhtemoc Campuzano

Highlights are presented regarding recent developments of the kinetic theory of granular matter. These concern the discovery of an exact kinetic equation and a related exact H-theorem both holding for finite $N-$body systems formed by…

Statistical Mechanics · Physics 2016-12-15 Massimo Tessarotto , Claudio Cremaschini

The group-theoretic approach is used to construct exact solutions to perfect fluid equations invariant under the Schrodinger group, or the l-conformal Galilei group, or the Lifshitz group. In each respective case, the velocity vector field…

Mathematical Physics · Physics 2026-05-22 Anton Galajinsky

We discuss and illustrate through numerical examples the relations between generating functionals, thermodynamic consistency (in particular the virial-free energy one), and uniqueness of the solution, in the integral equation theory of…

Condensed Matter · Physics 2009-11-10 R. Fantoni , G. Pastore

New exact solutions of relativistic perfect fluid hydrodynamics are described, including the first family of exact rotating solutions. The method used to search for them is an investigation of the relativistic hydrodynamical equations and…

Nuclear Theory · Physics 2011-05-13 M. I. Nagy

We present a method for generating exact diagonal $G_2$-cosmological solutions in dilaton gravity coupled to a radiation perfect fluid and with a cosmological potential of a special type. The method is based on the symmetry group of the…

General Relativity and Quantum Cosmology · Physics 2009-11-10 Stoytcho S. Yazadjiev

In this paper, we introduce a novel analytical solution to Tolman-Oppenheimer-Volkoff (TOV) equation, which is ultimately a hydrostatic equilibrium equation derived from the general relativity in the framework of relativistic isothermal…

General Relativity and Quantum Cosmology · Physics 2017-05-01 A. S. Saad , M. I. Nouh , A. A. Shaker , T. M. Kamel

We consider a self-gravitating system consisting of perfect fluid with spherical symmetry. Using the general expression of entropy density, we extremize the total entropy $S$ under the constraint that the total number of particles is fixed.…

General Relativity and Quantum Cosmology · Physics 2015-05-30 Sijie Gao

An algorithm based on the choice of a single monotone function (subject to boundary conditions) is presented which generates all regular static spherically symmetric perfect fluid solutions of Einstein's equations. For physically relevant…

General Relativity and Quantum Cosmology · Physics 2009-11-07 Kayll Lake

A brief summary of results on homotheties in General Relativity is given, including general information about space-times admitting an r-parameter group of homothetic transformations for r>2, as well as some specific results on perfect…

General Relativity and Quantum Cosmology · Physics 2009-10-28 J. Carot , A. M. Sintes

The present status of the shear-free perfect fluid conjecture in general relativity is discussed: I give a review of recent work and present a new formalism which may provide a better understanding of the problems encountered.

General Relativity and Quantum Cosmology · Physics 2025-09-17 Norbert Van den Bergh

In a recent manuscript published in the Arxives (arXiv:1610.03049v1), it is claimed that it should be more appropriate to refer to the equation of hydrostatic equilibrium in a static spherically symmetric spacetime, supported by an…

History and Philosophy of Physics · Physics 2016-11-22 L. Herrera

Using a new metric for generating rotating solutions, we derive in a general fashion the solution of an imperfect fluid and that of its conformal homolog. We discuss the conditions that the stress-energy tensors and invariant scalars be…

General Relativity and Quantum Cosmology · Physics 2014-01-29 Mustapha Azreg-Aïnou

The fluid models mentioned in the title are classified. All characteristics of the fluid are expressed through a master potential, satisfying an ordinary second order differential equation. Different constraints are imposed on this core of…

General Relativity and Quantum Cosmology · Physics 2015-05-27 B. V. Ivanov