Behavior of Cohesive Powder in Rotating Drums

We present experimental findings on the flowability and avalanching behavior of cohesive powders in a rotating drum. The main goal - beyond the scope of the current study - is to develop a method to understand and predict phenomena that precede the occurrences of events like avalanches and then to simulate this with the Discrete Element Method. In the present study, we focus on the characterization, classification, and description of the various events possible in cohesive powders - other than in non-cohesive particle systems - during rotation in a drum. Events are categorized based on their nature and we speculate on their relation to the micro-structure and properties of the powder. As main result, we show that repeatable and consistent results can be obtained in the characterization of cohesive powders when angle-based (e. g. local surface and global center-of-mass) parameters are used. Different events can be distinguished, especially for strong cohesion, bulk shear sliding is often replaced by other events like slumping.