Plugging of the Flow of Granular Materials during the Discharge from a Silo

Laboratory experiments and numerical simulations were performed to find the mechanism of the plugging during the gravitationally emptying a silo. Some interesting results were given by this investigation: 1) Two major slip lines can be seen symmetrically about a vertical midline in the continuous flow, but particles flow only on a one-side slip line was found at each moment; 2) At transition of the flow from one-side to the other, two-side flows collided each other on a vertical midline. And this collision possibly resulted in the formation of the arches of granular materials; 3) In the special case for 2) when arches were stable enough under certain geometrical condition the plugging of the flow occurred. For computer simulation on this issue, the Discrete Element Method specifically taking into account of rolling friction effect was used. Results of numerical simulations were in good agreement with the experimental measures not only in the flow pattern but also in the occurrence of the plugging.