  A variant of the Direct Simulation Monte Carlo method is used to study the
behavior of a granular gas, in two and three dimensions, under varying density,
restitution coefficient, and inelasticity regimes, for realistic vibrating wall
conditions. Our results agree quite well with recent experimental data. The
role of the energy injection mechanism is discussed, as well as the behavior of
state-functions, such as pressure, under realistic boundary conditions. Upon a
density increase, we find signals of a clustering transition.
