Bianchi Type-II Cosmological Model with Viscous Fluid
  A spatially homogeneous and locally rotationally symmetric Bianchi type-II
cosmological model under the influence of both shear and bulk viscosity has
been studied. Exact solutions are obtained with a barotropic equation of state
between thermodynamics pressure and the energy density of the fluid, and
considering the linear relationships amongst the energy density, the expansion
scalar and the shear scalar. Special cases with vanishing bulk viscosity
coefficients and with the perfect fluid in the absence of viscosity have also
been studied. The formal appearance of the solutions is the same for both the
viscous as well as the perfect fluids. The difference is only in choosing a
constant parameter which appears in the solutions. In the cases of either a
fluid with bulk viscosity alone or a perfect fluid, the barotropic equation of
state is no longer an additional assumption to be imposed; rather it follows
directly from the field equations.
