Bianchi Type-I String Dust Models with Bulk Viscosity in Lyra Geometry

Abstract

In the present study, we have investigated string dust models with bulk viscosity in Lyra geometry taking Bianchi type-I space–time as a source. To get the determinate model, we have assumed the conditions $$ \sigma_{1}^{1} \,\alpha \,\theta \,{\text{and}}\,\zeta \,\theta = \,{\text{constant}} $$ where $$ \sigma_{1}^{1} $$ the component of shear tensor $$ (\sigma_{\text{i}}^{\text{j}}) ,\,\theta$$ the expansion in the model, ζ the coefficient of bulk viscosity. We observed that string cosmological models are possible in the frame work of Lyra manifold with one of shear tensor component bears the constant ratio to expansion. The models satisfy reality condition in presence and absence of bulk viscosity. The anisotropy is maintained due to the presence of strings. The models in presence of bulk viscosity has point type singularity while in absence of bulk viscosity, the model represents cigar type singularity. The displacement vector of Lyra geometry is initially large but decreases with time in presence and absence of bulk viscosity. The other physical aspects are also discussed.