Experimental Study and DEM Modelling of the Contact Behaviour of Cylindrical Particles

In the food, chemical and pharmaceutical industry, cylindrical particles are often used and further processed in various production steps e.g. fluidization, drying and coating. To control and optimize these processes, it is essential to know and describe the particle kinematics and dynamics. An important tool to obtain these data is numerical simulations with the computational fluid dynamics (CFD) coupled with the discrete element method (DEM). In DEM, the interactions are calculated for each single particle based on models describing physical properties of particles and their mechanical behavior during slow, fast and repeated stressing [1-3]. For cylindrical particles, there is a lack of understanding of how particle shape influences the particle contact behavior in different scenarios. Especially for the exact calculation of the particle interactions in DEM, it is essential to describe the particle contact behaviour with a compatible contact model.

In this work, the influence of loading direction (contact geometry) and deformation behaviour (from elastic to plastic) on cylindrical particles during compression and shearing is investigated. The compression tests are performed with a Texture Analyser^®. For the measurement of particle-wall sliding friction, a self-developed setup at the University of Kaiserslautern is used. During the measurement of tangential forces, the particles are fixed to a flat holder and moved over a defined wall surface at different normal loads. In addition, experiments in a fluid bed rotor granulator equipped with a Magnetic Particle Tracking (MPT) system [4] are conducted in order to visualize and quantify the real particle kinetics and dynamics.

The intention of these investigations is the experimental calibration of contact models, which can be applied for numerical DEM studies of fluidization processes with cylindrical particles.

References

[1] Antonyuk S, Palis S and Heinrich S 2011 Powder Technology 206 88–98

[2] Antonyuk S, Heinrich S, Tomas J, Deen N G, van Buijtenen M S and Kuipers J A M 2010 Granular Matter 12 15–47

[3] Oschmann T, Hold J and Kruggel-Emden H 2014 Powder Technology 258 304–23

[4] Neuwirth, J., Antonyuk, S., Heinrich, S., Jacob, M.: CFD-DEM study and direct measurement of the granular flow in a rotor granulator, Chemical Engineering Science 86 (2013), 151-163.