  Taking into account of entropy generation during evolution of a viscous
fluid, we have estimated inverse Knudsen number, ideal hydrodynamic limit for
elliptic flow and QGP viscosity to entropy ratio in $\sqrt{s}$=62 and 200 GeV
Cu+Cu/Au+Au collisions. Viscosity to entropy ratio is estimated as
$\eta/s=0.17\pm 0.10\pm 0.20$, the first error is statistical, the second one
is systematic. In a central Au+Au collision, inverse Knudsen number is $\approx
2.80\pm 1.63$, which presumably small for complete equilibration. In peripheral
collisions it is even less. Ideal hydrodynamic limit for elliptic flow is
$\sim$40% more than the experimental flow in a central collision.
