Bianchi Type-III Bulk Viscous and Barotropic Perfect Fluid Cosmological Models in Lyra’s Geometry

Abstract

We have investigated Bianchi type III bulk viscous and barotropic perfect fluid cosmological models in the frame work of Lyra's geometry. To get deterministic models of universe, we have assumed the three conditions: (i) shear scalar (σ ) is proportional to the expansion (θ ). This leads to B = C n , where B and C are metric potentials. (ii) In presence of viscous fluid, the coefficient of viscosity of dissipative fluid is a power function of mass density ξ = ξ 0 ρ m , where ξ 0 and m are constant and (iii) in absence of viscosity, a proportionality relation between pressure and energy density of barotropic perfect fluid p = αρ, where α is a proportionality constant. In all the cases, we observed that the displacement vector β is large at beginning of the universe and reduces fast during its evolution so that its nature coincide with the behavior of cosmological constant .

Anisotropic Bianchi Type-III Bulk Viscous Fluid Universe in Lyra Geometry

“…This is an equation involving two unknown functions and which will admit solution if one of them is a known function of . To get a physically realistic model, Bali and Chandanani [25] and V. K. Yadav and L. Yadav [26] have assumed a supplementary condition = between the metric potentials and . This condition is based on the physical assumption that the shear scalar is proportional to the expansion scalar .…”

“…Bali and Chandnani [25] have investigated a Bianchi type-III bulk viscous dust filled universe in Lyra geometry under certain physical assumptions. Recently, V. K. Yadav and L. Yadav [26] have presented Bianchi type-III bulk viscous and barotropic perfect fluid cosmological models in Lyra's geometry with the assumption that the coefficient of viscosity of dissipative fluid is a power function of the energy density. In this paper, we investigate a Bianchi type-III universe filled with a bulk viscous fluid within the framework of Lyra geometry with time-dependent displacement vector field without assuming the barotropic equation of state for the matter field.…”

Bulk Viscous Bianchi Type-V Cosmological Model in f(R, T) Theory of Gravity

“…A bulk viscous fluid can be used to represent the back-reaction consequences of string formation. The bulk viscosity cosmological models have been discussed, and the model's nature has been discussed by Fabris (Fabris et al, 2006), Singh (Singh and Baghel, 2009), Yadav (Yadav and Yadav, 2011), Singh (Bali et al, 2012), Kiran (Kiran and Reddy, 2013), Mahanta (Mahanta, 2014), Rao (Bhaskara Rao et al, 2015), Tiwari (Tiwari and Tiwari, 2017), and Sahoo (Sahoo and Reddy, 2018). Very recently Goswami (Goswami et al, 2021) and Kotambkar (Kotambkar et al, 2021) have investigated the modeling of accelerating and the dynamical behaviours of Chaplygin gas, cosmological and gravitational "constants" with cosmic viscous fluid in different contexts.…”