Mankoc, C. (C.); Garcimartin, A. (Ángel); Zuriguel, I. (Iker); et al. "Role of vibrations in the jamming and unjamming of grains discharging from a silo". En . , 2009-07-28T08:46:06Z,
We present experimental results of the jamming of noncohesive particles discharged from a flat bottomed
silo subjected to vertical vibration. When the exit orifice is only a few grain diameters wide, the flow can be
arrested due to the formation of blocking arches. Hence, an external excitation is needed to resume the flow.
The use of a continuous gentle vibration is a usual technique to ease the flow in such situations. Even though
jamming is less frequent, it is still an issue in vibrated silos. There are, in principle, two possible mechanisms
through which vibrations may facilitate the flow: i a decrease in the probability of the formation of blocking
arches and ii the breakage of blocking arches once they have been formed. By measuring the time intervals
inside an avalanche during which no particles flow through the outlet, we are able to estimate the probability
of breaking a blocking arch by vibrations. The result agrees with the prediction of a bivariate probabilistic
model in which the formation of blocking arches is equally probable in vibrated and nonvibrated silos. This
indicates that the second aforementioned mechanism is mainly responsible for improving the flowability in
gently vibrated silos.