Related papers: Viscous fluid dynamics with decaying vacuum energy…
A generalized dynamical equation for the scale factor of the universe is proposed to describe the cosmological evolution, of which the $\Lambda$CDM model is a special case. It also provides a general example to show the equivalence of the…
In this paper, we investigate Bianchi type$-V$ cosmological models with bulk viscous fluid and time varying cosmological $\Lambda$ and Newtonian $G$ parameters. The Einstein's field equations have been transformed into a coupling…
We study the dynamics of a bulk viscosity model in the Eckart approach for a spatially flat Friedmann-Robertson-Walker (FRW) universe. We have included radiation and dark energy, assumed as perfect fluids, and dark matter treated as an…
We revise the conditions for the physical viability of a cosmological model in which dark matter has bulk viscosity and also interacts with dark energy. We have also included radiation and baryonic matter components; all matter components…
Viscous unified dark matter models aim to describe the dark sector of the Universe, as the dark matter fluid itself gives rise to an accelerated expansion due to a negative bulk viscous pressure. However, in most studies, radiation is often…
In this paper we solve Friedmann equations by considering a universal media as a non-perfect fluid with bulk viscosity and is described by a general "gamma law" equation of state of the form $p= (\gamma -1) \rho + \Lambda(t)$, where the…
From a phenomenological point of view, we analyze the dynamics of the Universe at late times by introducing a polynomial and hyperbolic bulk viscosity into the Einstein field equations respectively. We constrain their free parameters using…
Bulk viscous cosmological models is presented in the teleparallel ($F(T)$, where $T$ denotes torsion) gravity. In the teleparallel gravity, the Lagrangian of the gravitational action contains a general function $F(T)= T+ f(T)=(1+ \gamma)…
The behaviour of solutions to the Einstein equations with a causal viscous fluid source is investigated. In this model we consider a spatially flat Robertson-Walker metric, the bulk viscosity coefficient is related to the energy density as…
There is mounting observational evidence that the expansion of our Universe is undergoing a late-time acceleration. Among many proposals to describe this phenomenon, the cosmological constant seems to be the simplest and the most natural…
We consider a Friedmann-Robertson-Walker spacetime filled with both viscous radiation and nonviscous dust. The former has a bulk viscosity which is proportional to an arbitrary power of the energy density, i.e. $\zeta \propto \rho_v^{\nu}$,…
The whole article deals with the analysis of the cosmic model of Ruban's space-time in the context of a bulk viscosity impact in the form of Ricci dark energy within the framework Brans-Dicke theory (Brans and Dicke, Phys. Rev. 124, 925…
The bulk viscosity is introduced to model unified dark matter. The viscous unified model assumes the universe is filled with a single fluid with the bulk viscosity. We review the general framework of the viscous cosmology. The Hubble…
We analyze the effect of higher order viscosity corrections in a spatially homogeneous and isotropic universe. The viscous effects are modeled by introducing a second-order term to the energy density in the equation of state and on the…
In this paper, we study the viscous fluid cosmological model that when certain conditions are invoked mimics the $\Lambda$CDM model. The background equations governing the evolution of viscous interacting fluids in a multifluid system are…
We consider a nonsingular deflationary cosmological model with decaying vacuum energy density in universes of arbitrary spatial curvature. Irrespective of the value of $k$, the models are characterized by an arbitrary time scale $H_I^{-1}$…
Cylindrically symmetric inhomogeneous cosmological model for bulk viscous fluid distribution with electromagnetic field is obtained. The source of the magnetic field is due to an electric current produced along the z-axis. $F_{12}$ is the…
The statefinder diagnostic pair is adopted to differentiate viscous cosmology models and it is found that the trajectories of these viscous cosmology models on the statefinder pair $s-r$ plane are quite different from those of the…
In our previous works, we have analyzed the evolution of bulk viscous matter dominated universe with a more general form for bulk viscous coefficient, $\zeta=\zeta_{0}+\zeta_{1}\frac{\dot{a}}{a}+\zeta_{2}\frac{\ddot{a}}{\dot{a}}$ and also…
We analyze gravitational waves propagating in an isotropic cosmic fluid endowed with a bulk viscosity $\zeta$ and a shear viscosity $\eta$, assuming these coefficients to vary with fluid density $\rho$ as $\rho^\lambda$, with $\lambda=1/2$…