Mixing study of non-spherical particles using DEM

Abstract

In the last decade, granular flows have been studied extensively using DEM simulations. But only a little work has been done using non-spherical or real-shape particles even in the latest publications using powerful simulation tools making such study a need of the hour. This is important because the understanding of these particle shapes is crucial for design and development of real-life industrial mixers. In this work, we employed DEM (discrete element method) approach and used open-source simulation software LIGGGHTS to study the flow and mixing behaviour of polydisperse, non-spherical cohesionless particles in a cylindrical tank mixer. The mixer was agitated by using a four-bladed impeller and a blade-rake angle of 135°. We studied the flow and mixing behaviour by analysing particle velocities, contact forces and mixing performance. The mixing was quantified using a latest subdomain-based mixing index introduced by [1]. Different particle shapes were employed and expressed in terms of circularity/sphericity. We used seven different shapes in addition to spherical shape used for benchmarking. It is learnt that as we sway from circularity or sphericity, the mixing performance decreases. The complex (or in fact the real) shape particles are observed to have lower mixing performance compared to spherical particles under similar conditions.