  This proceeding briefly summarizes our recent investigations on the
correlations of flow harmonics in 2.76A TeV Pb--Pb collisions with viscous
hydrodynamics {\tt VISH2+1}. We calculated both the symmetric cumulants
$SC^{v}(m, n)$ and the normalized symmetric cumulants $NSC^{v}(m, n)$, and
found $v_{2}$ and $v_{4}$, $v_{2}$ and $v_{5}$, $v_{3}$ and $v_{5}$ are
correlated, $v_{2}$ and $v_{3}$, $v_{3}$ and $v_{4}$ are anti-correlated. We
also found $NSC^{v}(3, 2)$ are insensitive to the QGP viscosity, which are
mainly determined by the initial conditions.
