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We investigate the dependency of the inflow-wind structure of the hot accretion flow on the kinematic viscosity coefficient. In this regard, we propose a model for the kinematic viscosity coefficient to mimic the behavior of the…

High Energy Astrophysical Phenomena · Physics 2021-09-15 Fatemeh Zahra Zeraatgari , Liquan Mei , Amin Mosallanezhad

In this article, we investigate the geometry of static perfect fluid space-time on compact manifolds with boundary. We use the generalized Reilly's formula to establish a geometric inequality for a static perfect fluid space-time involving…

Differential Geometry · Mathematics 2023-09-08 Johnatan Costa , Rafael Diógenes , Neilha Pinheiro , Ernani Ribeiro

In the first part of this thesis, Kerr-Schild metrics and extended Kerr-Schild metrics are analyzed in the context of higher dimensional general relativity. Employing the higher dimensional generalizations of the Newman-Penrose formalism…

General Relativity and Quantum Cosmology · Physics 2012-04-03 Tomáš Málek

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 show that f(R)-gravity can, in general, give rise to cosmological viable models compatible with a matter-dominated epoch evolving into a late accelerated phase. We discuss the various representations of f(R)-gravity as an ideal fluid or…

Astrophysics · Physics 2008-11-26 S. Capozziello , S. Nojiri , S. D. Odintsov , A. Troisi

We investigate two-fluid BGK kinetic methods for binary fluids. The developed theory works for asymmetric as well as symmetric systems. For symmetric systems it recovers Sirovich's theory and is summarized in models A and B. For asymmetric…

Soft Condensed Matter · Physics 2009-11-10 Aiguo Xu

Using the 3+1 formalism of general relativity we obtain the equations governing the dynamics of spherically symmetric spacetimes with arbitrary sources. We then specialize for the case of perfect fluids accompanied by a flow of interacting…

General Relativity and Quantum Cosmology · Physics 2010-05-12 Marcelo Salgado

It is shown that the kinematic system describing planar non-steady motions of ideal fibre-reinforced fluids may be reduced to a single two-dimensional third-order partial differential equation in which time enters parametrically. A…

Exactly Solvable and Integrable Systems · Physics 2021-11-18 Dmitry K. Demskoi , Wolfgang K. Schief

A cosmological model with perfect fluid and self-interacting quintessence field is considered in the framework of the spatially flat Friedmann-Robertson-Walker (FRW) geometry. By assuming that all physical quantities depend on the volume…

General Relativity and Quantum Cosmology · Physics 2009-11-07 M. K. Mak , T. Harko

The kinematics of particles refer to events and tangent vectors, while that of waves refer to dual gradient planes. Special relativity [1-3] applies to both objects alike. Here we show that spacetime exchange symmetry [7] implicit in the…

General Physics · Physics 2010-05-31 Jens Madsen Houlrik , Germain Rousseaux

The system consisting of a self gravitating perfect fluid and scalar field is considered in detail. The scalar fields considered are the quintessence and ``tachyonic'' forms which have important application in cosmology. Mathematical…

General Relativity and Quantum Cosmology · Physics 2009-11-10 A. DeBenedictis , A. Das , S. Kloster

The differential equations satisfied by the wavefunction coefficients of conformally coupled scalars in a power-law cosmology can be recast into an iterative differential system of basis functions. These functions can be encoded within…

High Energy Physics - Theory · Physics 2026-05-19 Ji-Yuan Ke , Ping He

A covariant hamiltonian formalism for the dynamics of compact spinning bodies in curved space-time in the test-particle limit is described. The construction allows a large class of hamiltonians accounting for specific properties and…

General Relativity and Quantum Cosmology · Physics 2016-12-21 J. W. van Holten

In this work, we study the magnetic effects of gravity in the framework of special relativity. Imposing covariance of the gravitational force with respect to the Lorentz transformations, we show from a thought experiment that a…

General Physics · Physics 2018-05-01 R. S. Vieira , H. B. Brentan

A cylindrically symmetric perfect fluid spacetime with no curvature singularity is shown. The equation of state for the perfect fluid is that of a stiff fluid. The metric is diagonal and non-separable in comoving coordinates for the fluid.…

General Relativity and Quantum Cosmology · Physics 2009-11-10 L. Fernandez-Jambrina

A new kinetic model is proposed where the equilibrium distribution with bounded support has a range of velocities about two average velocities in 1D. In 2D, the equilibrium distribution function has a range of velocities about four average…

Fluid Dynamics · Physics 2023-08-15 Shashi Shekhar Roy , S. V. Raghurama Rao

We present two classes of inhomogeneous, spherically symmetric solutions of the Einstein-Maxwell-Perfect Fluid field equations with cosmological constant generalizing the Vaidya-Shah solution. Some special limits of our solution reduce to…

General Relativity and Quantum Cosmology · Physics 2019-10-09 Metin Gurses , Yaghoub Heydarzade

The configuration space of general relativity is superspace - the space of all Riemannian 3-metrics modulo diffeomorphisms. However, it has been argued that the configuration space for gravity should be conformal superspace - the space of…

General Relativity and Quantum Cosmology · Physics 2007-05-23 Bryan Kelleher

Einstein's field equations for timelike self-similar spherically symmetric perfect-fluid models are investigated. The field equations are rewritten as a first-order system of autonomous differential equations. Dimensionless variables are…

General Relativity and Quantum Cosmology · Physics 2010-05-12 Martin Goliath , Ulf S Nilsson , Claes Uggla

5-dimensional special relativity can be considered as the 5-dimensional extension of Carmeli's cosmological special relativity, as well as the flat specialization of 5-d brane world theory. To this framework we add a 5-dimensional perfect…

General Relativity and Quantum Cosmology · Physics 2007-05-23 Gianluca Gemelli
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