Bulk viscous matter and recent acceleration of the universe

We consider a cosmological model dominated by bulk viscous matter with a total bulk viscosity coefficient proportional to the velocity and acceleration of the expansion of the universe in such a way that ζ=ζ0+ζ1a˙a+ζ2a¨a˙. We show that there exist two limiting conditions in the bulk viscous coefficients ( ζ0 , ζ1 , ζ2 ) which correspond to a universe having a Big Bang at the origin, followed by an early decelerated epoch and then making a smooth transition into an accelerating epoch. We have constrained the model using the type Ia Supernovae data, evaluated the best estimated values of all the bulk viscous parameters and the Hubble parameter corresponding to the two limiting conditions. We found that even though the evolution of the cosmological parameters are in general different for the two limiting cases, they show identical behavior for the best estimated values of the parameters from both limiting conditions. A recent acceleration would occur if ζ~0+ζ~1>1 for the first limiting conditions and if ζ~0+ζ~1