A multi-superquadric DEM method for high-fidelity modelling mixing and breakage of non-spherical particles in rotary drums

• The multi-superquadric model with separation function is first developed. • The transient particle breakage rate is largely affected by rotational speed. • The movements of multi-superquadric and single particles are firstly co-integrated. • The multi-superquadric model can be further coupled with CFD-DEM framework. Non-spherical particles are widely encountered in engineering applications, yet their irregular shapes pose challenges for accurate modelling in the discrete element method (DEM) framework. This study develops a novel multi-superquadric particle model that incorporates both combination and separation operations for sub-particles, enabling the simulation of non-spherical particle breakage under specific trigger conditions. For the first time, the coexistence of intact multi-superquadric particles and their sub-particles post-separation is implemented within a unified computational domain while maintaining continuous motion integration. The combination sub-model is validated against experimental data and applied to investigate the effects of rotational speed on particle mixing in a horizontal drum. Additionally, the breakage sub-model is applied to investigate the particle breakage behaviors, according to the experimentally determined force-based binary (yes/no) decision criterion. The results show that rotational speed significantly influences the velocity distribution of multi-superquadric particles. A twofold increase in rotational speed (from 25 rpm to 50 rpm) reduces the mixing time by approximately 50 % and increases the transient breakage rate by 1.75 times. This study provides a robust modelling framework for analyzing complex non-spherical particle systems, offering new insights into particle breakage mechanisms and their impact on granular flows in industrial processes.