S. RAM ET AL.

14

tend to zero as . Therefore, the anisotropy in the

model is maintained throughout.

t

4. Conclusion

In this paper we have studied totally anisotropic Bianchi

type-II bulk viscous fluid cosmological models with time-

dependent gravitational and cosmological constants. We

have presented two classes of physically viable cosmo-

logical models for and We have obtained

expressions for physical parameter

1n1.n

,,,p

G and

as functions of time t. For 1n

, the model evolves with

a finite volume at and does not approach isotropy

as For large time, the energy density becomes zero.

The model is accelerating for

0t

.t

11n

12

3

mm

n

3

m

t

and is decelerating for

11

123 .

3

n

mmm

tn

For

, the model starts evolving with a big-bang singu-

larity at This model represents an accelerating or

decelerating universe according as is

greater than 3 or less than 3. The anisotropy is main-

tained throughout in the model. The cosmological term is

infinite initially and approaches to zero at late time. The

gravitational constant G is zero initially and gradually

increases and tends to infinity at late time. These are sup-

ported by recent results from the observations of the type

Ia supernova explosion (SNIa).

1n

0.t

12

tmmm

3

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