Bulk viscosity and matter creation in inhomogeneous cosmologies with a shear-free fluid source

A large class of viscous inhomogeneous and anisotropic cosmologies emerges due to the fact that all known exact solutions of Einstein's field equations with irrotational, shear-free, perfect-fluid sources can be recast as solutions for a fluid with the same kinematics but with an isotropic bulk-viscous stress. These solutions (physically limited if their source is a perfect fluid) acquire new meaning and a rich physical structure, either as classical fluids with bulk viscosity and/or as phenomenological models for matter creation or viscosity-driven inflation.