The study of anisotropic flow provides strong constrains to the evolution of the medium produced in heavy ion collisions and its event-by-event geometry fluctuations. The strength and predominance of these observables have long been related to collective behaviour in the formed medium. Recent results in small systems both at RHIC and LHC provide strong arguments for the formation of such medium at those scales.
PHENIX has measured the v2 and v3 anisotropic flow coefficients for p+Au, d+Au and He+Au collisions at 200GeV as well as d+Au at various lower energies. We have found a remarkable dependence of the flow amplitude with initial geometry which can be reproduced by hydrodynamic models.