  Using a hydrodyamic model of granular flows, we present very long time
simulations of a granular fluid in two dimensions without gravity and with
periodic boundary conditions in a square domain. Depending upon the values of
the viscosity, thermal conductivity and dissipation, we find for intermediate
times a metastable clustering state. For longer times the system is attracted
to either a shear band or a vortex state. Our results are in general agreement
with molecular dynamics simulations.
