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Related papers: Full Causal Bulk Viscous Cosmologies with time-var…

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A kinetic-fluid model describing the evolutions of disperse two-phase flows is considered. The model consists of the Vlasov-Fokker-Planck equation for the particles (disperse phase) coupled with the compressible Navier-Stokes equations for…

Analysis of PDEs · Mathematics 2017-04-06 Fucai Li , Yanmin Mu , Dehua Wang

Within the context of a cosmic space whose energy source is modeled with a perfect fluid, a uniform model of Universe based on a standard FRW cosmology containing decoupled mixed matter sources namely stiff matter and cosmic dust together…

General Relativity and Quantum Cosmology · Physics 2016-09-07 Denisa-Andreea Mihu

Bulk viscosity, which characterizes the irreversible dissipative resistance of a fluid to volume changes, has been proposed as a potential mechanism for explaining both early- and late-time accelerated expansion of the Universe. In this…

Cosmology and Nongalactic Astrophysics · Physics 2025-12-18 P. P. Avelino , A. R. Gomes , D. A. Tamayo

We consider Friedmann-Lema\^{\i}tre-Robertson-Walker flat cosmological models in the framework of general Jordan frame scalar-tensor theories of gravity with arbitrary coupling function and potential. For the era when the cosmological…

General Relativity and Quantum Cosmology · Physics 2011-01-06 Laur Järv , Piret Kuusk , Margus Saal

We consider the influence of the perturbative bulk viscosity on the evolution of the Hubble parameter in the QCD era of the early Universe. For the geometry of the Universe we assume the homogeneous and isotropic…

General Relativity and Quantum Cosmology · Physics 2010-11-24 A. Tawfik , M. Wahba , H. Mansour , T. Harko

In this work we present the cosmological dynamics of interacting dark energy models in the framework of particle creation mechanism. The particle creation mechanism presented here describes the true non equilibrium thermodynamics of the…

General Relativity and Quantum Cosmology · Physics 2017-06-07 Sujay Kr. Biswas , Wompherdeiki Khyllep , Jibitesh Dutta , Subenoy Chakraborty

We consider a universe with a bulk viscous cosmic fluid, in a flat Friedmann-Lemaitre-Robertson-Walker geometry. We derive the conditions for the existence of inflation, and those which at the same time prevent the occurrence of…

General Relativity and Quantum Cosmology · Physics 2017-04-05 I. Brevik , E. Elizalde , V. V. Obukhov , A. V. Timoshkin

Multidimensional cosmological model describing the evolution of a fluid with shear and bulk viscosity in $n$ Ricci-flat spaces is investigated. The barotropic equation of state for the density and the pressure in each space is assumed. The…

General Relativity and Quantum Cosmology · Physics 2010-04-30 V. R. Gavrilov , V. N. Melnikov , Roland Triay

We point out that the standard formulation of the cosmological constant problem itself is problematic since it is trying to apply the very large scale homogeneous cosmological model to very small (Planck) scale phenomenon. At small scales,…

General Relativity and Quantum Cosmology · Physics 2020-08-05 Qingdi Wang , William G. Unruh

We introduce a time-delay function in bulk viscosity cosmology. Even for bulk viscosity functions where closed-form solutions are known, because of the time-delay term the exact solutions are lost. Therefore in order to study the…

General Relativity and Quantum Cosmology · Physics 2022-11-23 Andronikos Paliathanasis

We study noncommutative classical Friedmann-Robertson-Walker cosmological models. The constant curvature of the spatial sections can be positive ($k=1$), negative ($k=-1$) or zero ($k=0$). The matter is represented by a perfect fluid with…

General Relativity and Quantum Cosmology · Physics 2017-01-06 G. Oliveira-Neto , A. R. Vaz

We consider the dynamics of a viscous cosmological fluid in the generalized Randall-Sundrum model for an anisotropic, Bianchi type I brane. To describe the dissipative effects we use the Israel-Hiscock-Stewart full causal thermodynamic…

General Relativity and Quantum Cosmology · Physics 2008-11-26 T. Harko , M. K. Mak

We discuss cosmology based on a Cuscuta-Galileon gravity theory, which preserves just two degrees of freedom. Although there exists no additional degrees of freedom, introduction of a potential of a scalar field changes the dynamics. The…

General Relativity and Quantum Cosmology · Physics 2022-05-17 Kei-ichi Maeda , Sirachak Panpanich

An LRS Bianchi type-V cosmological models representing a viscous fluid distribution with a time dependent cosmological term $\Lambda$ is investigated. To get a determinate solution, the viscosity coefficient of bulk viscous fluid is assumed…

General Relativity and Quantum Cosmology · Physics 2007-08-06 Anirudh Pradhan , J. P. Shahi , C. V. Singh

In this work we compile a few differential equations (ODEs) that arise from the relativistic equations in cosmological models that consider the ``constants'' as scalars functions dependent on time and they are described as perfect as well…

General Relativity and Quantum Cosmology · Physics 2009-11-10 José Antonio Belinchón , P. Dávila

Bulk viscous cosmological models is presented in the teleparallel ($F(T)$, where $T$ denotes torsion) gravity. In the teleparallel gravity, the Lagrangian of the gravitational action contains a general function $F(T)= T+ f(T)=(1+ \gamma)…

General Relativity and Quantum Cosmology · Physics 2025-07-22 Partha Sarathi Debnath , Chanchal Mondal , B. C. Paul

We present here a phenomenological cosmological model under perfect fluid distribution with a stiff equation of state $p=\rho$. The erstwhile cosmological constant is assumed to be a time dependent variable, i.e., $\Lambda = \Lambda(t)$ in…

Astrophysics · Physics 2008-11-26 Saibal Ray , Utpal Mukhopadhyay

A cosmological model with an inhomogeneous viscous dark fluid coupled with dark matter in a flat Friedman-Robertson-Walker universe is investigated. The influence of dark matter on the behavior of an inhomogeneous viscous fluid of this…

General Relativity and Quantum Cosmology · Physics 2015-06-22 E. Elizalde , V. V. Obukhov , A. V. Timoshkin

Gravitational and hydrodynamical perturbations are analysed in a relativistic plasma containing a mixture of interacting fluids characterized by a non-negligible bulk viscosity coefficient. The energy-momentum transfer between the…

General Relativity and Quantum Cosmology · Physics 2009-11-11 Massimo Giovannini

In this paper, we investigate Bianchi type-$VI$ cosmological model for the universe filled with dark energy and viscous fluid in the presence of cosmological constant. Also, we show accelerating expansion of the universe by drawing volume…

General Relativity and Quantum Cosmology · Physics 2013-08-29 J. Sadeghi , Ali R. Amani , N. Tahmasbi