  Event-by-event fluctuations in the initial density distributions of the
fireballs created in relativistic heavy-ion collisions lead to event-by-event
fluctuations of the final anisotropic flow angles, and density inhomogeneities
in the initial state cause these flow angles to vary with the transverse
momentum of the emitted particles. It is shown that these effects lead to
characteristically different transverse momentum dependencies for anisotropic
flow coefficients extracted from different experimental methods. These
differences can be used to experimentally constrain flow angle fluctuations in
the final state of heavy-ion collisions which, in turn, are sensitive to the
initial state density fluctuations and the shear viscosity of the expanding
fireball medium.
