Related paper Linear and non-linear flow modes in Pb-Pb collisions at $\sqrt{s_{\rm NN}} =$ 2.76 TeV Centrality dependence of $\chi$ in Pb--Pb collisions at $\sqrt{s_{_{\rm NN}}} = 2.76$ TeV. Hydrodynamic calculations from ${\tt VISH2+1}$ are shown in shaded areas and the one from ${\tt IP}$-${\tt Glasma+MUSIC+UrQMD}$ are shown with open bands. [png] [eps]