Event anisotropy $v_2$ at STAR

Collective flow reflects the dynamical evolution in high-energy heavy ion collisions. In particular, the elliptic flow reflects early collision dynamics.We present a systematic analysis of elliptic flow ($v_2$) for identified particles measured in Au + Au and Cu + Cu collisions at $\sqrt{s_{NN}}$ = 200 GeV. Number of quark scaling is tested in the intermediate $p_T$ region and in the smaller system (Cu + Cu). The Cu + Cu collisions results are compared with those from ideal hydrodynamic model calculations.