  In an ideal hydrodynamic model, with an equation of state where the
confinement-deconfinement transition is a cross-over at $T_{co}=196 MeV$, we
have simulated $\sqrt{s}$=200 GeV Au+Au collisions. Simultaneous description of
the experimental charged particle's $p_T$ spectra and elliptic flow require
that in central (0-10%) Au+Au collisions, initial energy density scales with
the binary collision number density. In less central collisions, experimental
data demand scaling with the participant density. Simulation studies also
indicate that in central collisions viscous effects are minimal.
