An Investigation On The Dynamic Characteristics Of Granular Materials Flowing Through A Hopper

Understanding the dynamic behavior of the gravity-driven granular materials in the hopper has been a hotspot and conundrum in the field of granular matter. In this paper, we focus on the dynamical characteristics of the gravity-driven granular materials flowing through the hopper. We investigate the relationship between the flow rate and pressure as well as the the problem of the stability for free-fall granualr stream after flowing through the hopper.The results show:(1) Use the elastic deformation device and find that the pressure for the bottom of the hopper remaincal mechanism is the bottom of the pressure to maintain a constant. Combination the phase diagram for granular jamming transition and the saturation effects acting on the wall. As a result, the pressure for the bottom of the hopper remains constant as the gravity-driven granular materials flowing through the hopper, which deny Aguirre who argued flow rate independence of pressure recently. We conclude that: granular matter in the silo unloading process also has the the Jassen effect similar to the static granular.(2) Free-fall granular stream flowing through the hopper and lead to cluster instability have relation with the formation of shearing band and the compression of granular media (shearing expansion effect). The shear rate exceeds a critical value lead to shear instability when the medium flows through the funnel, which cause the granualr density and viscosity is coupled in the shearing motion. Combining the inference that Jaeger and his colleagues consider that the nanoNewton cohesive forces lead to instability of cluster, which explain that the cluster instability of granular stream better.(3) The physical mechanism for the bottleneck effect is the pressure-saturation effect as granular media flows through the bottleneck. To suppress the bottleneck effect, and further improve the flow rate, inspired by the granular stream flow rate and pressure and granular stream stability principle, we construct two level hopper (has the minimum channel) structure model, which can enhance the flow of the whole system. In theory, in this way we can improve the flow flate as powders through containers with bottleneck.