Unjamming a granular hopper by vibrationA. Janda1, D. Maza1, A. Garcimartín1, E. Kolb2, J. Lanuza2 and E. Clément2
1 Departamento de Física, Facultad de Ciencias, Universidad de Navarra - E-31080 Pamplona, Spain, EU
2 Laboratoire de Physique et Mécanique des Milieux Hétérogènes, associé au CNRS (UMR 7636) l'ESPCI et aux Universités Paris 6 et Paris 7 - 10 rue Vauquelin, 75005 Paris France, EU
received 20 March 2009; accepted in final form 30 June 2009; published July 2009
published online 5 August 2009
We present an experimental study of the outflow of a hopper continuously vibrated by a piezoelectric device. Outpouring of grains can be achieved for apertures much below the usual jamming limit observed for non-vibrated hoppers. Granular flow persists down to the physical limit of one grain diameter, a limit reached for a finite vibration amplitude. For the smaller orifices, we observe an intermittent regime characterized by alternated periods of flow and blockage. Vibrations do not significantly modify the flow rates both in the continuous and the intermittent regime. The analysis of the statistical features of the flowing regime shows that the flow time significantly increases with the vibration amplitude. However, at low vibration amplitude and small orifice sizes, the jamming time distribution displays an anomalous statistics.
45.70.Ht - Avalanches.
45.70.Mg - Granular flow: mixing, segregation and stratification.
© EPLA 2009