Signatures of glass formation in a fluidized bed of hard spheres
  We demonstrate that a fluidized bed of hard spheres during defluidization displays properties associated with formation of a glass. The final state is rate dependent, and as this state is approached, the bed exhibits heterogeneity with increasing time and length scales. The formation of a glass results in the loss of fluidization and an arrest of macroscopic particle motion. Microscopic motion persists in this state, but the bed can be jammed by application of a small increase in flow rate. Thus a fluidized bed can serve as a test system for studies of glass formation and jamming. 
Daniel I. Goldman and Harry L. Swinney