Viscous Fluid Cosmology in Bianchi Type-I Space-Time

Abstract

The paper presents a spatially homogeneous and anisotropic Bianchi type-I cosmological model consisting of a dissipative fluid. The field equations are solved explicitly by using a law of variation for mean Hubble parameter, which is related to average scale factor and yields a constant value for deceleration parameter. We find that the constant value of deceleration parameter describes the different phases of the evolution of universe. A barotropic equation of state (p = γρ) together with a linear relation between shear viscosity and expansion scalar, is assumed. It is found that the viscosity plays a key role in the process of the isotropization of the universe. The presence of viscous term does not change the fundamental nature of initial singularity. The thermodynamical properties of the solutions are studied and the entropy distribution is also given explicitly.

Anisotropic dark energy models with constant deceleration parameter

“…Recently in a series of works, Singh and Kumar [27][28][29][30][31][32] and Kumar and Singh [33][34][35] have extended the work to anisotropic Bianchi-I space-time in general relativity and some of its modified theories. In this paper, we show how the constant deceleration parameter models with metric (1) behave in the presence of perfect fluid and anisotropic DE components.…”

Anisotropic cosmological models in f(R,T) gravity with variable deceleration parameter

“…Recently, the bulk viscous matter content has been discussed along with cosmological constant in the framework of Bianchi type-I space time [50]. Later, the spatially homogeneous anisotropic Bianchi type-I model with bulk viscous fluid matter was studied with the assumption of constant deceleration parameter in the framework of f (R, T ) gravity theory through the explanation of the energy conditions [51,52,53,54,55,56]. This work is motivated by the aforesaid literature.…”

Bianchi-I Space-time with Variable Gravitational and Cosmological “Constants”

“…Thus the relevance of the relation (24) is justified. In a series of works, Singh and Kumar [14,[39][40][41][42] and Kumar and Singh [43][44][45] have also utilized the above form of Hubble parameter for obtaining exact solutions of anisotropic Bianchi type-I and II cosmological models in general relativity and some scalar-tensor theories of gravitation.…”