  Simulated results from a 2+1D relativistic viscous hydrodynamic model have
been compared to the experimental data on the centrality dependence of
invariant yield, elliptic flow ($v_{2}$), and hexadecapole flow ($v_{4}$) as a
function of transverse momentum ($p_{T}$) of charged hadrons in Au-Au
collisions at $\sqrt{s_{\rm {NN}}}$ = 200 GeV. Results from two types of
initial transverse energy density profile, one based on the Glauber model and
other based on Color-Glass-Condensate (CGC) are presented. We observe no
difference in the simulated results on the invariant yield of charged hadrons
for the calculations with different initial conditions. The comparison to the
experimental data on invariant yield of charged hadrons supports a shear
viscosity to entropy density ratio ($\eta/s$) between 0 to 0.12 for the 0-10%
to 40-50% collision centralities. The simulated $v_{2}(p_{T})$ is found to be
higher for a fluid with CGC based initial condition compared to Glauber based
initial condition for a given collision centrality. Consequently the Glauber
based calculations when compared to the experimental data requires a lower
value of $\eta/s$ relative to CGC based calculations. In addition, a centrality
dependence of the estimated $\eta/s$ is observed from the $v_{2}(p_{T})$ study.
The $v_{4}(p_{T})$ for the collision centralities 0-10% to 40-50% supports a
$\eta/s$ value between 0 - 0.08 for a CGC based initial condition. While
simulated results using the Glauber based initial condition for the ideal fluid
evolution under estimates the $v_{4}(p_{T})$ for collision centralities 0-10%
to 30-40%.
