We study Bianchi type-II model with time varying constant under the self similarity approach. In first part of the paper we have studied the model by considering time variable G and Λ and obtain the solutions of the field equations by using linear equation of state (EOS) of the form ρ = np + ρ o where n and ρo are constants. It is observed that G must be time growing function while nature of Λ depends on the nature of γ . In the second part of paper we have studied the model by considering variable speed of light (VSL) and obtain the similar types of solutions as in the first model and all the physical parameters which depends on cdt. Arriving to the conclusion that c must be growing time function and Λ depends on value γ.

Dark energy of phantom or quintessence nature with an equation of state parameter almost equal to -1 often leads to a finite future singularity. The singularities in the dark energy universe, by assuming bulk viscosity in the framework of Kaluza-Klein theory of gravitation have been discussed. Particularly, it is proved, that the physically natural assumption of letting the bulk viscosity be proportional to the scalar expansion in a spatially 5D FRW universe, can derive the fluid into the phantom region ( < -1), even if it lies in the quintessence region ( >-1) in the non viscous case. It is also shown that influence of the viscosity term acts to shorten the singularity time but it does not change the nature of singularity in the framework of higher dimensional space time.