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We consider a Bianchi type-I Polytropic bulk viscous fluid cosmological model with variable G and {\Lambda}. To get a deterministic model, we assume some conditions of A, B, C, and polytropic relation to find the results. physical…

General Physics · Physics 2014-03-11 Rishi Kumar Tiwari , Mukesh Sharma , Sonia Sharma

In this paper, we have analyzed the significance of bulk viscosity in an axially symmetric Bianchi type-I model to study the accelerated expansion of the universe. We have considered four bulk viscosity parameterizations for the…

General Relativity and Quantum Cosmology · Physics 2022-12-21 Archana Dixit , Anirudh Pradhan , Vinod Kumar Bhardwaj , A. Beesham

In this paper, we investigate Bianchi type$-V$ cosmological models with bulk viscous fluid and time varying cosmological $\Lambda$ and Newtonian $G$ parameters. The Einstein's field equations have been transformed into a coupling…

The present study deals with spatially homogeneous and totally anisotropic Bianchi type V cosmological model in presence of bulk viscous fluid source with time dependent gravitational constant G and cosmological term Lambda. The coefficient…

General Relativity and Quantum Cosmology · Physics 2022-04-22 Nawsad Ali

In this paper we study the evolution of spatially homogeneous and anisotropic Bianchi type-I Universe models with the cosmological constant, \Lambda, and filled with nonlinear viscous fluid. The dynamical equations for these models are…

Cosmology and Nongalactic Astrophysics · Physics 2015-06-16 Nouraddin Mostafapoor , Oyvind Gron

Bianchi type V viscous fluid cosmological model for barotropic fluid distribution with varying cosmological term $\Lambda$ is investigated. We have examined a cosmological scenario proposing a variation law for Hubble parameter $H$ in the…

General Relativity and Quantum Cosmology · Physics 2015-06-04 Raj Bali , Pratibha Singh , J. P. Singh

An analysis is presented of the Bianchi type I cosmological models with a bulk viscosity when the universe is filled with the stiff fluid $p = \epsilon$ while the viscosity is a power function of the energy density, such as $\eta = \alpha…

General Relativity and Quantum Cosmology · Physics 2009-11-10 Wung-Hong Huang

We investigated a bulk viscous fluid universe with cosmological constant {\Lambda} by assuming that the bulk viscosity to be proportional to the Hubble parameter. We found that for an expanding universe, the (relative) matter density will…

General Relativity and Quantum Cosmology · Physics 2024-01-25 Jinwen Hu , Huan Hu

In this paper, we investigate the evolution of cosmological perturbations within the context of Bianchi Type$-I$ spacetimes. We consider models containing viscous fluids with evolving cosmological (\LL) and Newtonian gravitational (G)…

General Relativity and Quantum Cosmology · Physics 2023-11-08 Alnadhief H. A. Alfedeel , Maye Elmardi , Amare abebe

Bianchi type I cosmological models are studied that contain a stiff fluid with a shear viscosity that is a power function of the energy density, such as $\zeta = \alpha \epsilon^n$. These models are analyzed by describing the cosmological…

General Relativity and Quantum Cosmology · Physics 2016-08-31 Wung-Hong Huang

A new class of exact solutions of Einstein's field equations with bulk viscous fluid for an LRS Bianchi type-I spacetime is obtained by using deceleration parameter as variable. The value of Hubble's constant $H_{0}$ is found to be less…

General Relativity and Quantum Cosmology · Physics 2008-11-26 Anirudh Pradhan , Vandana Rai , R. S. Singh

Anisotropic Bianchi-III cosmological model is investigated with variable gravitational and cosmological constants in the framework of Einstein's general relativity. The shear scalar is considered to be proportional to the expansion scalar.…

General Relativity and Quantum Cosmology · Physics 2015-06-23 S. K. Tripathy , D. Behera , T. R. Routray

A Bianchi type I string cosmological model in the presence of a magnetic flux is investigated. A few plausible assumptions regarding the parametrization of the cosmic string and magneto-fluid are introduced and some exact analytical…

General Relativity and Quantum Cosmology · Physics 2015-05-01 Bijan Saha , Mihai Visinescu

Cylindrically symmetric inhomogeneous cosmological model for bulk viscous fluid distribution with electromagnetic field is obtained. The source of the magnetic field is due to an electric current produced along the z-axis. $F_{12}$ is the…

General Relativity and Quantum Cosmology · Physics 2008-11-26 Anirudh Pradhan , Vandana Rai , Kanti Jotania

The behavior of magnetic field in plane symmetric inhomogeneous cosmological models for bulk viscous distribution is investigated. The coefficient of bulk viscosity is assumed to be a power function of mass density $(\xi =\xi_{0}\rho^{n})$.…

General Relativity and Quantum Cosmology · Physics 2009-11-11 Anirudh Pradhan , Purnima Pandey

The irrotational Bianchi V cosmological model under the influence of both shear and bulk viscosity, together with heat flux, has been studied. Exact solutions for the model are obtained with three physically viable assumptions. The first…

General Relativity and Quantum Cosmology · Physics 2019-12-09 A. Banerjee , Abhik Kumar Sanyal

In this paper, we have investigated some features of anisotropic accelerating Bianchi type-I cosmological model in the presence of two non-interacting fluids, i.e. one usual string and other dark energy fluid towards the gravitational field…

General Physics · Physics 2020-04-20 S. H. Shekh , V. R. Chirde

In the present work we have searched the existence of the late time acceleration of the universe with string fluid as source of matter in Bianchi V space-time. To get the deterministic solution, we choose the scale factor as increasing…

General Physics · Physics 2015-06-04 Anil Kumar Yadav

In this paper we study the evolution of the equation of state of viscous dark energy in the scope of Bianchi type III space-time. We consider the case when the dark energy is minimally coupled to the perfect fluid as well as direct…

Cosmology and Nongalactic Astrophysics · Physics 2015-06-19 Hassan Amirhashchi

The present study deals with spatially homogeneous and anisotropic Bianchi-I cosmological model representing massive strings. The energy-momentum tensor, as formulated by Letelier (Phys. Rev. D 28: 2414, 1983) has been used to construct…

General Physics · Physics 2014-03-11 Chanchal Chawla , R. K. Mishra , Anirudh Pradhan