颗粒物质从稀疏流到密集流转变的普适规律

Global property of the dilute-to-dense transition of granular flows in a 2D channel

二维颗粒流实验研究发现 ,当初始稀疏颗粒流量固定 ,出口的尺寸减小到一临界值 ,或固定出口的尺寸 ,颗粒流量增大到一临界值时 ,都会发生流量的突然减小 ,从稀疏流转变为密集流 .得到了临界流量与出口尺寸、颗粒尺寸及通道宽度之间的普适标度关系 ,揭示了“瓶颈效应”

Dilute\|to\|dense transition of granular flow is observed in a two\|dimensional channel with confined exit. It is found that for a fixed width of the channel and exit there is a maximum outflow rate. This is reached when the inflow reaches a critical rate Q c as the outflow changes from dilute to dense, and the flow rate drops abruptly. We find that a rescaled critical flow rate is a function of a scaling variable λ only. The form of λ suggests that the dilute-to-dense transition is a global property of the flow.