Bianchi types I and V bulk viscous fluid cosmological models in f(R, T) gravity theory

Open Physics ◽  
2014 ◽  
Vol 12 (10) ◽  
Author(s):  
Shri Ram ◽  
Priyanka Kumari
Keyword(s):  
Viscous Fluid ◽  
Cosmological Models ◽  
Gravity Theory ◽  
Field Equations ◽  
Bulk Viscous Fluid ◽  
Bulk Viscous ◽  
Special Value ◽  
The Universe ◽  
Average Scale Factor ◽  
Bianchi Types

AbstractIn this paper we present non-singular Bianchi types I and V cosmological models, in the presence of bulk viscous fluid and within the framework of f(R,T) gravity theory. Exact solutions to the field equations are obtained by choosing a particular form of the function f(R,T) and a special value for the average scale factor of the model, which corresponds to a time- dependent deceleration parameter. The cosmological models initially accelerate for a certain period of time and thereafter decelerate. The physical and kinematical properties of the models of the universe are discussed.

scholarly journals Anisotropic Bianchi Type-III Bulk Viscous Fluid Universe in Lyra Geometry

2013 ◽  
Vol 2013 ◽  
pp. 1-5 ◽  
Author(s):  
Priyanka Kumari ◽  
M. K. Singh ◽  
Shri Ram
Keyword(s):  
Cosmological Model ◽  
Viscous Fluid ◽  
Bianchi Type ◽  
Lyra Geometry ◽  
Scale Factor ◽  
Field Equations ◽  
Type Iii ◽  
Bulk Viscous Fluid ◽  
Bulk Viscous ◽  
The Universe

An anisotropic Bianchi type-III cosmological model is investigated in the presence of a bulk viscous fluid within the framework of Lyra geometry with time-dependent displacement vector. It is shown that the field equations are solvable for any arbitrary function of a scale factor. To get the deterministic model of the universe, we have assumed that (i) a simple power-law form of a scale factor and (ii) the bulk viscosity coefficient are proportional to the energy density of the matter. The exact solutions of the Einstein’s field equations are obtained which represent an expanding, shearing, and decelerating model of the universe. Some physical and kinematical behaviors of the cosmological model are briefly discussed.

scholarly journals Kaluza–Klein Bulk Viscous Fluid Cosmological Models and the Validity of the Second Law of Thermodynamics in f(R, T) Gravity

2017 ◽  
Vol 72 (4) ◽  
pp. 365-374 ◽  
Author(s):  
Gauranga Charan Samanta ◽  
Ratbay Myrzakulov ◽  
Parth Shah
Keyword(s):  
Cosmological Model ◽  
Viscous Fluid ◽  
Second Law Of Thermodynamics ◽  
Second Law ◽  
Field Equations ◽  
Geometrical Properties ◽  
Bulk Viscous Fluid ◽  
Bulk Viscous ◽  
Two Stages ◽  
Kaluza Klein

Abstract:The authors considered the bulk viscous fluid in f(R, T) gravity within the framework of Kaluza–Klein space time. The bulk viscous coefficient (ξ) expressed as $\xi = {\xi _0} + {\xi _1}{{\dot a} \over a} + {\xi _2}{{\ddot a} \over {\dot a}},$ where ξ0, ξ1, and ξ2 are positive constants. We take p=(γ−1)ρ, where 0≤γ≤2 as an equation of state for perfect fluid. The exact solutions to the corresponding field equations are given by assuming a particular model of the form of f(R, T)=R+2f(T), where f(T)=λT, λ is constant. We studied the cosmological model in two stages, in first stage: we studied the model with no viscosity, and in second stage: we studied the model involve with viscosity. The cosmological model involve with viscosity is studied by five possible scenarios for bulk viscous fluid coefficient (ξ). The total bulk viscous coefficient seems to be negative, when the bulk viscous coefficient is proportional to ${\xi _2}{{\ddot a} \over {\dot a}},$ hence, the second law of thermodynamics is not valid; however, it is valid with the generalised second law of thermodynamics. The total bulk viscous coefficient seems to be positive, when the bulk viscous coefficient is proportional to $\xi = {\xi _1}{{\dot a} \over a},$$\xi = {\xi _1}{{\dot a} \over a} + {\xi _2}{{\ddot a} \over {\dot a}}$ and $\xi = {\xi _0} + {\xi _1}{{\dot a} \over a} + {\xi _2}{{\ddot a} \over {\dot a}},$ so the second law of thermodynamics and the generalised second law of thermodynamics is satisfied throughout the evolution. We calculate statefinder parameters of the model and observed that it is different from the ∧CDM model. Finally, some physical and geometrical properties of the models are discussed.

scholarly journals Accelerating universe with binary mixture of bulk viscous fluid and dark energy

2021 ◽  
pp. 2150148
Author(s):  
Nishant Singla ◽  
M. K. Gupta ◽  
Anil Kumar Yadav ◽  
G. K. Goswami
Keyword(s):  
Dark Energy ◽  
Binary Mixture ◽  
Viscous Fluid ◽  
Accelerating Universe ◽  
Model Parameters ◽  
Density Parameter ◽  
Bulk Viscous Fluid ◽  
Bulk Viscous ◽  
De Formula ◽  
The Universe

In this paper, we have proposed a model of accelerating universe with binary mixture of bulk viscous fluid and dark energy (DE) and probed the model parameters: present values of Hubble’s constant [Formula: see text], equation of state paper of DE [Formula: see text] and density parameter of DE [Formula: see text] with recent observational [Formula: see text] data (OHD) as well as joint Pantheon compilation of SN Ia data and OHD. Using cosmic chronometric technique, we obtain [Formula: see text] and [Formula: see text] by restricting our derived model with recent OHD and joint Pantheon compilation SN Ia data and OHD, respectively. The present age of the universe in derived model is estimated as [Formula: see text]. Also, we observe that derived model represents a model of transitioning universe with transition redshift [Formula: see text]. We have constrained the present value of jerk parameter as [Formula: see text] with joint OHD and Pantheon data. From this analysis, we observed that the model of the universe, presented in this paper, shows a marginal departure from [Formula: see text]CDM model.

BULK VISCOUS FRW COSMOLOGY IN LYRA GEOMETRY

2001 ◽  
Vol 10 (03) ◽  
pp. 339-349 ◽  
Author(s):  
A. PRADHAN ◽  
V. K. YADAV ◽  
INDRAJIT CHAKRABARTY
Keyword(s):  
Energy Density ◽  
Viscous Fluid ◽  
Mass Density ◽  
Lyra Geometry ◽  
Frw Cosmology ◽  
Frw Universe ◽  
Bulk Viscous Fluid ◽  
Bulk Viscous ◽  
Lyra’S Geometry ◽  
The Universe

We have studied an isotropic homogeneous FRW universe in the presence of a bulk viscous fluid within the framework of Lyra's geometry. We have obtained exact solutions of the Sen equations assuming the deceleration parameter to be constant. The coefficient of bulk viscosity has been assumed to be a power function of the mass density. With this assumption, we have considered the behavior of the displacement field and the energy density for both power-law and exponential expansions of the universe. We show that our models are generalised and we obtain the results of previous works by considering k=0 and k=-1.

scholarly journals A New Class of Brans - Dicke Cosmological Models with Causal Viscous Fluid

1997 ◽  
Vol 50 (5) ◽  
pp. 903 ◽  
Author(s):  
G. P. Singh ◽  
A S. G. Ghosh ◽  
Aroonkumar Beesham
Keyword(s):  
Viscous Fluid ◽  
Nonequilibrium Thermodynamics ◽  
Cosmological Solution ◽  
Cosmological Models ◽  
Fluid Source ◽  
New Class ◽  
Bulk Viscous Fluid ◽  
Bulk Viscous ◽  
Friedmann Robertson Walker

The behaviour of solutions to the Brans–Dicke equations of Friedmann–Robertson–Walker models with bulk viscous fluid source described by full (i.e. non-truncated) causal nonequilibrium thermodynamics is investigated. A new class of cosmological solution is obtained for all spatial sections (k = 0, ± 1).

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