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Effect of hopper angle on granular clogging

2019; American Physical Society; Volume: 99; Issue: 3 Linguagem: Inglês

10.1103/physreve.99.032901

2470-0061

Diego López-Rodríguez, Diego Gella, Kiwing To, Diego Maza, Ángel Garcimartín, Iker Zuriguel,

Landslides and related hazards

We present experimental results of the effect of the hopper angle on the clogging of grains discharged from a two-dimensional silo under gravity action. We observe that the probability of clogging can be reduced by three orders of magnitude by increasing the hopper angle. In addition, we find that for very large hopper angles, the avalanche size ($\ensuremath{\langle}s\ensuremath{\rangle}$) grows with the outlet size ($D$) stepwise, in contrast to the case of a flat-bottom silo for which $\ensuremath{\langle}s\ensuremath{\rangle}$ grows smoothly with $D$. This surprising effect is originated from the static equilibrium requirement imposed by the hopper geometry to the arch that arrests the flow. The hopper angle sets the bounds of the possible angles of the vectors connecting consecutive beads in the arch. As a consequence, only a small and specific portion of the arches that jam a flat-bottom silo can survive in hoppers.