Phase changes in an inelastic hard disk system with a heat bath under weak gravity for granular fluidization

We performed numerical simulations on a two-dimensional inelastic hard disk system under gravity with a heat bath to study the dynamics of granular fluidization. Upon increasing the temperature of the heat bath, we found that three phases, namely, the condensed phase, locally fluidized phase, and granular turbulent phase, can be distinguished using the maximum packing fraction and the excitation ratio, or the ratio of the kinetic energy to the potential energy. It is shown that the system behavior in each phase is very different from that of an ordinary vibrating bed.