Predicting the flow mode from hoppers using the discrete element method

In this work, the discrete element method (DEM) is used to assess powder flow from hoppers and the results are compared to widely-used hopper design charts. These design charts delineate mass-flow and funnel-flow behavior based on the hopper wall angle and a given set of material properties. The modeled system consists of hoppers with various wall angles and frictional, non-cohesive, spherical particles. The performance is assessed by measuring the particle residence times, particle velocities, and the extent of segregation during discharge. A Mass Flow Index (MFI) based on the velocity profile data is used to quantitatively characterize the nature of the flow pattern as mass-flow, funnel-flow, or some intermediate. The DEM predictions are generally in very good agreement with the Jenike design charts. The level of agreement shown here indicates that DEM cannot only reproduce the current estimates of hopper performance, but also provide additional insight into the flow–such as the internal granular structure–that may be difficult to obtain otherwise.