Raj Bali

Bianchi Type-III String Cosmological Models with Time Dependent Bulk Viscosity

Bianchi type-III string cosmological models with bulk viscous fluid for massive string are investigated. To obtain the determinate model of the universe, we assume that the coefficient of bulk viscosity ξ is inversely proportional to the expansion θ in the model and expansion θ in the model is proportional to the shear σ. This leads to B = lCn, where l and n are constants. Behaviour of the model in the presence and absence of bulk viscosity is discussed. The physical implications of the models are also discussed in detail.

Bianchi Type-I Massive String Magnetized Barotropic Perfect Fluid Cosmological Model in General Relativity

Bianchi type-I massive string cosmological model with magnetic field of barotropic perfect fluid distribution through the techniques used by Latelier and Stachel is investigated. To obtain the deterministic model of the universe, it is assumed that the universe is filled with barotropic perfect fluid distribution. The magnetic field is due to electric current produced along the x-axis with infinite electrical conductivity. The behaviour of the model in the presence and absence of magnetic field together with other physical aspects is further discussed.

L.R.S. Bianchi Type I string dust magnetized cosmological models

AbstractL.R.S. Bianchi Type I string dust cosmological models with and without magnetic field following the techniques used by Letelier and Stachel, is investigated. To get a determinate solution, we assume a conditionσ is proportional to scalar of expansion θ where σ is shear and θ is scalar of expansion and which leads to A=ℓ Bnwhere n is a constant and ℓ is proportionality constant. Some special models are also investigated by introducing the transformation,

Bianchi type-I cosmological model for perfect fluid distribution in Lyra geometry

\tfrac{{A_4 }}{A} = w

Bianchi Type-IX viscous fluid cosmological model in general relativity

, which leads to Riccati type differential equation. The physical and geometrical aspects of the models are also discussed.

Bianchi Type III Bulk Viscous Barotropic Fluid Cosmological Models with Variable G and Λ

A Bianchi type-III string cosmological model with bulk viscous fluid for massive string is investigated. To get a determinate solution, a supplementary condition B=Cn, between metric potentials, is used whereB and C are function of time alone. The behaviour of the model in presence and absence of bulk viscosity, is discussed.

Some expanding and shearing viscous fluid cosmological models in general relativity

In this paper, we have investigated Bianchi type-I cosmological model with time dependent gauge function β for perfect fluid distribution within the framework of Lyra geometry. To get the deterministic model of the universe, we have assumed that eigenvalue (σ11) of shear tensor (σij) is proportional to the expansion (θ). This leads to A=(BC)n, where A,B,C are metric potentials. The physical and geometrical aspects of the model and singularities in the model are also discussed.

Conformally flat tilted Bianchi Type-V cosmological models in general relativity

The object of this paper is to investigate the behavior of the magnetic field in a cosmological model for perfect fluid distribution. The magnetic field is due to an electric current produced along thex axis. It is assumed that expansion (θ) in the model is proportional toσ11, the eigenvalue of the shear tensorσij. The behavior of the model when the magnetic field tends to zero and other physical properties are also discussed.