How do biomaterials and granular materials move in a horizontal drum under varying process conditions?

Granular material dynamics have been modelled extensively in moving horizontal drums for a number of industrial applications. Biomaterial dynamics in a moving drum has also been described in a number of publications (silk, wool and leather), but very rarely using computer modelling and simulation. Discrete element method (DEM) is a proven technique to accurately describe the motion of bodies in a constrained space. Other authors have described the motion of fabric in the drum using three basic models: rotating circular bundle, rigid fibre, and completely flexible fibre. The study reported in this paper considers the rotating circular bundle and the completely flexible fibre model on sensitive biomaterials. The inclusion of shear and tensile modulus through Hertz-Mindlin contact models (with bonding), helps to describe the dynamics of biomaterials, and the variation of the processing parameters gives researchers insight into the forces that can be exerted on sensitive materials before rupture. The research examines the variation of rotation speed, load-volume, density and the inclusion of water into the horizontal drum and their influence on the coefficients of friction and restitution. The research then goes on to analyse the influence the changes have on the angle of repose (of materials slipping off lifters) and the resulting changes in velocity when these process parameters are varied. It is concluded that both the rotating circular bundle and completely flexible fibre model can be used in proprietary DEM software and allow the researcher to alter processing parameters to prevent damage to sensitive materials.