Dark energy nature of viscus universe in f(Q)-gravity with observational constraints

In this study, we have investigated the dark energy behavior of the viscus-fluid in f(Q)-gravity in a flat, isotropic and homogeneous Friedmann-Lemaitre-Robertson-Walker (FLRW) space-time metric. We have considered the linear form of f(Q) function as f(Q) = -alpha Q - beta with alpha > 0 and beta > 0 as model parameters. We have solved the field equations for the scale factor a(tau) and found a(tau) = c(1)[sinh(k(2)tau)](k3), where k(2) = root 3 alpha beta(1+omega)(2)-24 pi xi(0)beta(1+omega)/2 root 2 alpha and k(3) = 2 alpha/3 alpha(1+omega)-24 pi xi(0) and c(1) is an integrating constant, omega is the EoS for normal matter and xi(0) is generated from bulk-viscus fluid. We have calculated the several cosmological parameters for this scale factor and studied their physical and geometrical behavior along the observational data sets H(z) and Union 2.1 compilation of SNe Ia data sets. We have observed that the beta factor reveals the presence of cosmological constant and for beta = 0, the acceleration drives by the bulk-viscosity of the fluid and it behaves just like dark energy model without cosmological constant. We have studied the effective EoS omega(eff) and found - 0.2807 <= omega(eff) <= -0.1760. We have evaluated the age of the present universe as 13.68 Gyrs. and also, we have studied the nature of deceleration parameter with the signature-flipping point at z(t) = 0.5, 1.87 and the present value of deceleration parameter q(0) is obtained as - 0.3309, -0.8035.