  It is shown that a simultaneous comparison of both elliptic and triangular
flow from (2+1)-dimensional viscous fluid dynamics with recent measurements in
Pb+Pb collisions at the Large Hadron Collider (LHC) favors a small specific
shear viscosity (eta/s)_QGP approximately equal to 1/(4pi) for the quark-gluon
plasma. Using this viscosity value, the relative magnitude of the elliptic and
triangular flow is well described with Monte-Carlo Glauber (MC-Glauber) initial
conditions while Monte-Carlo Kharzeev-Levin-Nardi (MC-KLN) initial conditions
require twice as large viscosity to reproduce the elliptic flow and then
underpredict triangular flow by about 30%.
