Viscous cosmological fluids and large-scale structure

In this paper, we study the viscous fluid cosmological model that when certain conditions are invoked mimics the $Λ$CDM model. The background equations governing the evolution of viscous interacting fluids in a multifluid system are derived. The Markov Chain Monte Carlo (MCMC) simulation is applied to constrain the best-fit cosmological parameters with Supernova Type 1a data. In addition, linear cosmological perturbations are investigated in a dust-matter-dominated frame using a $1+3$ covariant formalism approach. It is evident from the perturbation results obtained that the model predicts the disintegration of bound structures of large-scale structures in the late-time universe. Published in SAIP2023 Proceedings, South African Institute of Physics