We assume the four dimensional induced matter of the 5D Ricci flat bouncing cosmological solution contains a perfect fluid. The big bounce singularity of simple 5D cosmological model is studied with the cosmological term = αρ and = βH 2 where α and β are constants and ρ and H are respectively energy density and Hubble parameter. This big bounce singularity is found to be an event horizon at which the scale factor and mass density of the universe are finite, while the pressure is infinite.

In this paper we consider the five dimensional cosmological model with variable gravitational and cosmological constants in the presence of perfect fluid in Kaluza-Klein theory of gravitation. The exact solutions of the field equations are obtained by using the gamma law equation of state p = (γ − 1)ρ in which the parameter γ depends on scale factor R. A unified description of early universe is presented with the assumption = βH 2 in which inflationary phase is followed by radiation dominated phase. The various physical aspects of the cosmological models are also discussed in the framework of higher dimensional space time.

In this paper we present a number of classes of solutions of the Einstein's field equations with variable G, and bulk viscosity for a Kaluza-Klein type of cosmological model. The solutions are obtained by using γ -law equation of state p = (γ − 1)ρ, where adiabatic parameter γ -varies continuously as the universe expand. A unified description of the early evolution of the universe is discussed with number of possible assumption on the bulk viscous term and gravitational constant in which an inflationary phase followed by radiation-dominated phase. We also investigate the cosmological model with constant and time dependent bulk viscosity along with constant and time dependent gravitational constant. In all cases, the cosmological constant found to be positive and decreasing function of time which supports the results obtained from recent supernovae Ia observations. The important physical behaviour of the early cosmological model has also been discussed in the frame work of higher dimensional space-time.

In this paper we investigate the -CDM universe by selecting the specific time dependent form of , viz.˙ ∝ H 3 , in the context of 5-dimensional space time. Timedependent form of equation of state parameter w is derived along with a possible signature flip of deceleration parameter q. It is also observed that a present age of the Universe, calculated for some specific values of parameter agrees very well with the observational data.

In this paper we have obtained the exact solution of the Einstein field equations by using global equation of state of the form p = 1 3 ρφ, where φ is a function of the scale factor R for Zeldovich fluid satisfying G = G 0 (R R0) m. We also studied the two variable Λ model, viz. Λ ∼ (Ṙ R) 2 and Λ ∼ ρ under the assumption that the equation of state parameter ω is time-dependent i.e. ω = ω(t) in the framework of Kaluza-Klein theory of gravitation.