  We present a new numerical algorithm based on a relative energy scaling for
collisional kinetic equations allowing to study numerically their long time
behavior, without the usual problems related to the change of scales in
velocity variables. It is based on the knowledge of the hydrodynamic limit of
the model considered, but is able to compute solutions for either dilute or
dense regimes. Several applications are presented for Boltzmann like equations.
This method is particularly efficient for numerical simulations of the granular
gases equation with dissipative energy: it allows to study accurately the long
time behavior of this equation and is very well suited for the study of
clustering phenomena.
