Bianchi Type-I String Cosmological Model with Bulk Viscosity and Time-Dependent Λ term

Einstein field equations with the cosmological constant is considered in the presence of bulk viscosity in a Bianchi type-I universe. Solutions of the field equations are obtained by assuming the following conditions: the bulk viscosity is proportional to the expansion scalar ξ∝θ; the expansion scalar is proportional to shear scalar θ∝σ; and Λ is proportional to the Hubble parameter Λ∝H. The corresponding interpretations of the cosmological solutions are also discussed.