Statistical properties of gravity-driven granular discharge flow under the influence of an obstacle

Abstract

Abstract. Two-dimensional granular discharge flow driven by gravity under the influence of an obstacle is experimentally investigated. A horizontal exit of width W is opened at the bottom of vertical Hele-Shaw cell filled with stainless-steel particles to start the discharge flow. In this experiment, a circular obstacle is placed in front of the exit. Thus, the distance between the exit and obstacle L is also an important parameter. During the discharge, granular-flow state is acquired by a high-speed camera. The bulk discharge-flow rate is also measured by load cell sensors. The obtained high-speed-image data are analyzed to clarify the particle-level granular-flow dynamics. Using the measured data, we find that the obstacle above the exit affects the granularflow field. Specifically, the existence of obstacle results in large horizontal granular temperature and small packing fraction. This tendency becomes significant when L is smaller than approximately 6D g when W 4D g , where D g is diameter of particles.

Obstacle-shape effect in a two-dimensional granular silo flow field

“…This tendency is consistent with the flow rate reduction due to the obstacle effect [25,30]. Note that, the discharge flow rate is always steady independently of obstacle shapes [25,30]. In Fig.…”

“…3(a)), the relation between the clogging and the circular obstacle is not so clear. Moreover, we have confirmed that discharge flow rate is almost always steady even in the alternate flow regime [30].…”

“…7(a)). It should be noted that all the experiments show steady flow [25,30] even right before the clogging. Although some numerical simulations have reported the increase of the flow rate by the effect of obstacle [31,32], these studies have simulated the inclined-bottom-wall silo flow.…”

Shape dependence of resistance force exerted on an obstacle placed in a gravity‐driven granular silo flow

“…1. The system is basically identical to that used in 3,24 . We built a two-dimensional (2D) granular silo with a horizontal bottom wall.…”

“…However, the typical flow features for granular silo flow (e.g., steadiness independent of layer's thickness) are preserved in this system. More detail characterization and the study on clogging with this experimental system are reported in 3,24 . The videos of particle motions can be found in 26 .…”