Laminar and turbulent flows in a vibrated granular system

A viscous fluid confined in a closed channel has two flow patterns, namely a laminar flow and a turbulent flow. Although already the onset and properties of each pattern have extensively been explored in various geometric fluid systems, very little is known about the flow pattern of a discrete medium. Thus, herein, we reported an experimental study on the type of flow in a vertically vibrated, annular, and granular system. It was found that the system presents either a laminar granular flow or a turbulent granular flow in different vibration modes. With the help of the Reynolds numbers of the granular system, the flow patterns were explained and identified. Finally, our results revealed a property peculiar to the granular flow which is similar to, albeit at the same time different from, viscous fluids. [Display omitted] •Both laminar flow and turbulent flow are observed in a vibrated granular system.•Reynolds numbers of the granular system are used to identify the flow patterns.•Granular flow patterns are very different from the flow patterns of viscous fluids.