  We analyze correlations between the event-plane angles in different intervals
of pseudorapidity within the 3+1-dimensional viscous hydrodynamics with the
Glauber-model initial conditions. As predicted earlier, the fluctuations in the
particle production mechanism in the earliest stage, together with asymmetry of
the emission profiles in pseudorapidity from the forward- and backward going
wounded nucleons, lead to the torque effect, namely, decorrelation of the
event-plane angles in distant pseudorapidity bins. We use two- or three-bin
measures of correlation functions to quantify the effect, with the latter
compared to the recent data from the CMS collaboration. We find a sizable
torque effect, with magnitude larger at RHIC than at the LHC.
