  Viscous relativistic hydrodynamics in 3+1 dimensions is applied to describe
heavy ion collisions at RHIC and LHC. We present calculations of observables
that are sensitive to the longitudinal structure of the created system. In
particular we present pseudo-rapidity correlations and demonstrate their
dependence on both the initial state and short range correlations introduced
via a microscopic transport description. We further demonstrate the effect of a
varying temperature dependence of the shear viscosity to entropy density ratio
on rapidity dependent flow harmonics.
