Figure 3

The ratio $v_{2}\{2, |\Delta\eta| > 0.8\} / v_{2}[2, |\Delta\eta| > 0.8]$ in Pb--Pb collisions at $\sqrt{s_{_{\rm NN}}} = 2.76$ TeV. The different panels show the centrality evolution of the measurements Hydrodynamic calculations with MC-Glauber initial conditions and $\eta/s =$ 0.08 , with MC-KLN initial conditions and $\eta/s =$ 0.20 , with Trento initial conditions and temperature dependent $\eta/s$  and AMPT initial conditions and $\eta/s =$ 0.08  are shown in green dot-dashed and orange dashed curves, and magenta and grey shaded areas, respectively.