  Simulation results of dense granular gases with particles of different size
are compared with theoretical predictions concerning the pair-correlation
functions, the collison rate, the energy dissipation, and the mixture pressure.
The effective particle-particle correlation function, which enters the equation
of state in the same way as the correlation function of monodisperse granular
gases, depends only on the total volume fraction and on the dimensionless width
A of the size-distribution function. The ''global equation of state'' is
proposed, which unifies both the dilute and the dense regime.
  The knowledge about a global equation of state is applied to steady-state
situations of granular gases in the gravitational field, where averages over
many snapshots are possible. The numerical results on the density profile agree
perfectly with the predictions based on the global equation of state, for
monodisperse situations. In the bi- or polydisperse cases, segregation occurs
with the heavy particles at the bottom.
