  A new class of LRS Bianchi type ${\rm VI}_{0}$ cosmological models with free
gravitational fields and a variable cosmological term is investigated in
presence of perfect fluid as well as bulk viscous fluid. To get the
deterministic solution we have imposed the two different conditions over the
free gravitational fields. In first case we consider the free gravitational
field as magnetic type whereas in second case `gravitational wrench' of unit
`pitch" is supposed to be present in free gravitational field. The viscosity
coefficient of bulk viscous fluid is assumed to be a power function of mass
density. The cosmological constant $\Lambda$ is found to be a decreasing
function of time and positive which is corroborated by results from recent
supernovae Ia observations. The physical and geometric aspects of the models
are discussed.
