DEM study on mixing behaviors of concave-shaped particles in rotating drum based on level-set method

Granular mixing is a complex phenomenon that is commonly encountered in various engineering disciplines. A large number of past studies have mainly focused on the mixing properties of convex-shaped granular materials, while the mixing behaviors of concave-shaped granular materials have not been well studied. In this study, spherical harmonic functions are used to describe the spherical and concave shapes of individual particles. The level set function is an implicit function consisting of a set of points that can be used to determine the contact points between particles. Then, the influences of the particle shape and rotational speed on the mixing behaviors of the granular material within a horizontal drum are analyzed by the discrete element method (DEM). Results indicate that concave particles have higher coordination numbers and closer contact patterns than spherical particles, which results in greater normal collision forces, larger dynamic angle of repose and lower mixability. [Display omitted] •Concave-shaped particles are modeled by the spherical harmonic functions.•The normal overlaps between concave particles are obtained by the level set method.•The mixing properties of spherical and concave particles in the drum are compared.•The mixing rate of concave particles decreases with decreasing particle sphericity.•Concave particles have closer contact modes and larger contact forces than spheres.