Viscous fluid universe interacting with scalar field

1987 ◽  
Vol 26 (2) ◽  
pp. 175-187 ◽  
Author(s):  
Koijam Manihar Singh ◽  
K. S. Bhamra
Keyword(s):  
Scalar Field ◽  
Viscous Fluid

scholarly journals Brans - Dicke Cosmology with Causal Viscous Fluid

1996 ◽  
Vol 49 (5) ◽  
pp. 899 ◽  
Author(s):  
N Banerjee ◽  
A Beesham
Keyword(s):  
Scalar Field ◽  
Cosmological Model ◽  
Viscous Fluid ◽  
Exact Solutions ◽  
Power Function ◽  
Causal Theory ◽  
Scale Factor ◽  
Scalar Tensor Theory ◽  
Equilibrium Thermodynamics ◽  
Tensor Theory

Exact solutions for the spatially flat (k = 0) Robertson–Walker cosmological model in Brans–Dicke scalar tensor theory have been obtained in the presence of a causal viscous fluid. It is found that if the scale factor is a power function of the scalar field, then solutions can be obtained in the full causal theory but not in the truncated theory of non-equilibrium thermodynamics.

Hamiltonian Formalism of Bianchi Type I Model for Fluid Bulk and Shearing Viscosity

2021 ◽  
Author(s):  
Shouvik Sadhukhan ◽  
Alokananda Kar
Keyword(s):  
Scalar Field ◽  
Viscous Fluid ◽  
Bianchi Type ◽  
Hamiltonian Formalism ◽  
Big Bang ◽  
Type I ◽  
Scale Factors ◽  
Anisotropic Expansion ◽  
Large Anisotropy

In this paper we will consider the cosmic fluid to be dissipating i.e it has both bulk and shearing viscosity. We propose the Hamiltonian formalism of Bianchi type 1 cosmological model for cosmic fluid which is dissipating i.e it has both shearing and bulk viscosity. We have considered both the equation of state parameter ω and the cosmological constant Λ as the function of volume V(t) which is defined by the product of three scale factors of the Bianchi type 1 line element. We propose a Lagrangian for the anisotropic Bianchi type-1 model in view of a variable mass moving in a variable potential . We can decompose the anisotropic expansion of Bianchi type 1 in terms of expansion and shearing motion by Lagrangian mechanism. We have considered a canonical transformation from expanding scale factor to scalar field ø which helps us to give the proper classical definition of that scalar field in terms of scale factors of the mentioned model. By this transformation we can express the mass to be moving in a scalar potential field. This definition helps us to explain the nature of expansion of universe during cosmological inflation. We have used large anisotropy(as in the cases of Bianchi models) and proved that cosmic inflation is not possible in such large anisotropy. Therefore we can conclude that the extent of anisotropy is less in case of our universe. Otherwise the inflation theory which explained the limitations of Big Bang cannot be resolved. In the case of bulk and shearing viscous fluid we get the solution of damped harmonic oscillator after the cosmological inflation.Part I contains the calculations of bulk viscous fluids and Part II contains the calculations of bulk and shearing viscous fluid.At the end we have also provided the relation of shearing and expansion.Part III will give the approximation of low viscosity to solve the viscous fluid problem.

COSMOLOGICAL MODELS IN GENERALIZED SCALAR–TENSOR THEORY WITH CAUSAL VISCOUS FLUID

1998 ◽  
Vol 07 (06) ◽  
pp. 849-856
Author(s):  
G. P. SINGH ◽  
S. G. GHOSH ◽  
AROONKUMAR BEESHAM
Keyword(s):  
Scalar Field ◽  
Viscous Fluid ◽  
Nonequilibrium Thermodynamics ◽  
Coupling Parameter ◽  
Scalar Tensor Theory ◽  
Bulk Viscous Fluid ◽  
Tensor Theory ◽  
Bulk Viscous ◽  
Friedmann Robertson Walker ◽  
Causal Thermodynamics

We consider generalized Brans–Dicke theory in which the coupling parameter is not constant but a function of the scalar field. Friedmann–Robertson–Walker models with bulk viscous fluid source described by full (i.e., nontruncated) causal nonequilibrium thermodynamics are analyzed. Exact solutions for the flat case have been obtained. Our results are compared with those in the usual Brans–Dicke theory with causal thermodynamics.

Isotropic Cosmological Model in Generalized Scalar Tensor Theory with Bulk Viscosity

1997 ◽  
Vol 06 (01) ◽  
pp. 119-124 ◽  
Author(s):  
N. Banerjee ◽  
Aroonkumar Beesham
Keyword(s):  
Scalar Field ◽  
Cosmological Model ◽  
Viscous Fluid ◽  
Bulk Viscosity ◽  
Conformal Transformation ◽  
Scalar Tensor Theory ◽  
Bulk Viscous Fluid ◽  
Tensor Theory ◽  
Bulk Viscous ◽  
Isotropic Cosmological Model

In this paper both exponential and power law solutions for the flat Robertson–Walker cosmological model have been derived in a generalized Brans–Dicke theory, where the parameter ω is a function of the scalar field, along with a bulk viscous fluid. The solutions are obtained in Dicke's revised units and these are also given in the original atomic units via the conformal transformation prescribed by Dicke.

GENERALIZED SCALAR–TENSOR THEORY FOR BIANCHI SPACETIME MODELS

2004 ◽  
Vol 19 (09) ◽  
pp. 703-711
Author(s):  
NARAYAN CHANDRA CHAKRABORTY ◽  
SUBENOY CHAKRABORTY
Keyword(s):  
Scalar Field ◽  
Viscous Fluid ◽  
Einstein Equations ◽  
Physical Parameters ◽  
Scalar Tensor Theory ◽  
Coupling Constant ◽  
Bulk Viscous Fluid ◽  
Tensor Theory ◽  
Bulk Viscous ◽  
Variable Coupling

This work deals with Bianchi cosmological models where geometry is coupled to a scalar field with variable coupling constant (depending on the scalar field). Considering a bulk viscous fluid, the possibility of exponential or power law form of solutions have been examined. The modified Einstein equations have been solved with some reasonable assumptions among the physical parameters and solutions have been discussed.

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