Phase transition and flow-rate behavior of merging granular flows

Abstract

Merging of granular flows is ubiquitous in industrial, mining, and geological processes. However, its behavior remains poorly understood. This paper studies the phase transition and flow-rate behavior of two granular flows merging into one channel. When the main channel is wider than the side channel, the system shows a remarkable two-sudden-drops phenomenon in the outflow rate when gradually increasing the main inflow. When gradually decreasing the main inflow, the system shows obvious hysteresis phenomenon. We study the flow-rate-drop phenomenon by measuring the area fraction and the mean velocity at the merging point. The phase diagram of the system is also presented to understand the occurrence of the phenomenon. We find that the dilute-to-dense transition occurs when the area fraction of particles at the joint point exceeds a critical value ϕ(c)=0.65±0.03.

Comparative Study and Optimizaion of Traffic and Granular Merging Flow

“…If the solid fraction is below 0.65 in the channel, the channel is in low density flow (or dilute flow). The critical solid fraction of 0.65 agrees with literature [1,9]. Figure 5 shows the illustration of the LH and HL state of the granular flow system.…”

“…We emphasize that the results of traffic and granular merging flows presented here are different from our previous work (see Ref. [8][9]) in that we study a wider side channel.…”

“…Recent experiments show that, synchronized traffic is often observed localized near bottlenecks like the on-ramps [7,8]. Similarly, in a granular flow system, the merging of particles can trigger different flowing patterns in the upward channels, such as dilute flow and dense flow [9].…”

Discrete element crowd model for pedestrian evacuation through an exit

“…When a group of particles flow through a silo in granular flow, the interactions among the particles may lead to the spontaneous development of clogs, as found in experimental granular flow observations. [39][40][41] The 034501-6 intermittent flow was also observed in the crowd flow through an exit as shown in Figs. 8 and 9(a).…”

“…In this figure, the temporary interruptions of the flow are caused by arches that block the exit, while the downward spikes indicates the temporary blockage of exit. When a group of particles flow through a silo in granular flow, the interactions among the particles may lead to the spontaneous development of clogs, as found in experimental granular flow observations [38,39,40]. The intermittent flow was also observed in the crowd flow through an exit as shown in Fig.…”