The cosmological model incorporating viscous fluid within the framework of general relativity

Resumen

Dark matter and dark energy, elusive elements of the universe, exert gravitational forces of attraction or repulsion, influencing the cosmological model. This phenomenon, known as cosmic acceleration, has been the subject of theoretical and observational studies spanning many decades. In this paper we have presented the cosmological models in presence of viscous fluid. Incorporation of cosmological constant  and gravitational constant  makes model more realistic. We solve the model in two phases: with case first, we assume that the viscosity of fluids is a power function of density. While another case comprises that the viscosity of the cosmological model is to be considered as the form of scalar expansion. To get the deterministic model, we have assumed a power law of gravitational constant . The relationship between viscosity and density; and with viscosity and scalar expansion determines the existence of dark energy. The geometrical aspect of the cosmological models also discussed.