Influence of granule velocity on gravity-driven granular flow

In this Letter, we present the results of our study on the influence of granule velocity on the granular flow state. The maximum outflow rate of the dilute flow state increases with an increase in granule velocity, whereas the outflow rate of the dense flow state remains unchanged. In addition, increasing granule velocity can extend the region of the dilute flow state and shrink that of the dense flow state. These observations can be explained by the relationship between the flow rate and the packing fraction at the bottleneck under a fixed particle number condition. -- Highlights: → We find a larger granule velocity helps maintain a dilute flow state of granular flow. → Increasing granule velocity can increase the maximum flow rate for the dilute flow. → The outflow rate for the dense flow remains unchanged. → The relationships between the flow rate and the packing fraction have the standard form of the granule flow.