scholarly journals Modeling of Accelerating Universe with Bulk Viscous Fluid in Bianchi V Space‐Time

2021 ◽  
pp. 2100007
Author(s):  
G. K. Goswami ◽  
Anil Kumar Yadav ◽  
B. Mishra ◽  
S. K. Tripathy
Keyword(s):  
Viscous Fluid ◽  
Space Time ◽  
Accelerating Universe ◽  
Bulk Viscous Fluid ◽  
Bulk Viscous ◽  
Bianchi V

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.

scholarly journals PLANE-SYMMETRIC INHOMOGENEOUS BULK VISCOUS COSMOLOGICAL MODELS WITH VARIABLE Λ

2003 ◽  
Vol 12 (05) ◽  
pp. 941-951 ◽  
Author(s):  
ANIRUDH PRADHAN ◽  
HARE RAM PANDEY
Keyword(s):  
Cosmological Model ◽  
Viscous Fluid ◽  
Cosmological Constant ◽  
Ad Hoc ◽  
Fluid Distribution ◽  
Geometric Features ◽  
Plane Symmetric ◽  
Bulk Viscous Fluid ◽  
Variable Λ ◽  
Bulk Viscous

A plane-symmetric non-static cosmological model representing a bulk viscous fluid distribution has been obtained which is inhomogeneous and anisotropic and a particular case of which is gravitationally radiative. Without assuming any ad hoc law, we obtain a cosmological constant as a decreasing function of time. The physical and geometric features of the models are also discussed.

scholarly journals Dynamics of Bianchi V Ih universe with bulk viscous fluid in modified gravity

2018 ◽  
Vol 15 (03) ◽  
pp. 1850036 ◽  
Author(s):  
B. Mishra ◽  
Sankarsan Tarai ◽  
S. K. J. Pacif
Keyword(s):  
Viscous Fluid ◽  
Dynamical Behavior ◽  
Momentum Tensor ◽  
Matter Field ◽  
Energy Conditions ◽  
Anisotropic Universe ◽  
Late Time ◽  
Bulk Viscous Fluid ◽  
Bulk Viscous ◽  
Theory Of Gravity

In this paper, the dynamical behavior of the anisotropic universe has been investigated in [Formula: see text] theory of gravity. The functional [Formula: see text] has been rescaled in the form [Formula: see text], where [Formula: see text] is the Ricci scalar and [Formula: see text] is the trace of energy momentum tensor. Three cosmological models are constructed using the power law expansion in Bianchi type [Formula: see text] ([Formula: see text]) universe for three different values of [Formula: see text], where the matter field is considered to be of bulk viscous fluid. It is observed that the anisotropic [Formula: see text] model in the modified theory of gravity is in agreement with a quintessence phase for the value of [Formula: see text] and [Formula: see text]. We could not obtain a viable cosmological model in accordance with the present day observations for [Formula: see text]. The bulk viscous coefficient in both the cases are found to be positive and remain constant at late time. The physical behaviors of the models along with the energy conditions are also studied.

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.

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