In de Sitter model, the scale factor is taken as R = [e.sup.((m+1)/2)[xi]t], where [xi] is a positive constant.
In the de Sitter model, the dark energy density decreases with increase in time and asymptotically reduces to a positive constant.
In the de Sitter model, DE dominates at late phase of EoS parameter and bulk viscous fluid plays an important role at early universe.
In a Universe devoid of matter described by equations (4.4), the Weyl conformal trace-free tensor [C.sub.[alpha][beta][gamma][mu]] never vanishes, in contrast to the de Sitter model
equipped with curvature (4.6).
The de Sitter model
. We can display the intriguing model discovered in 1917 by the Dutch astronomer Willem de Sitter by running the program with any choice of [H.sub.0], [[Omega].sub.0] = 0, and [[Omega].sub.[Lambda]] = 1.
It is observed that for z = 1 (i.e., at initial time) it is infinite but at z = 0 (i.e., at present time) it is closer to zero and at z = -1 it completely dies out which matches with the present day observations, which indicate that our model at present time (z = 0) is closer to the de Sitter model
and attains complete de Setter model at z = -1; i.e., we can say that the Bianchi type-I space-time reduces to flat FRW (isotropic) soon after the inflation.