Experimental investigation of vibration-induced bulk solids transport and segregation. Quarterly report ending March 31, 1996

An experimental investigation of the motion of a single large sphere in a bed of dry granular material subjected to vertical vibration is presented. We have studied the rise time of the sphere as a function of vibration parameters, frequency and amplitude. While previous results report a decreasing rise time with increasing relative acceleration, we evidence the existence of a critical frequency where the rise time jumps to greater values before decreasing again. We also show that the rise time scales with the velocity amplitude of vibration and the transition corresponds approximately to a doubling of rise time. The results reported are over a rather narrow range of input accelerations, and generally involve gross phenomena of heaping and fluidization. Observations of the dynamic trajectory of the rising particle are also reported through the use of a novel non-intrusive particle tracking system. 16 refs., 7 figs