Suppression of segregation in ternary granular mixtures with large density differences through mixer geometric optimization: A discrete element method–smoothed particle hydrodynamics coupling study

Significant differences in particle density frequently induce severe segregation during mixing processes. Although the addition of liquid can mitigate this issue, the underlying interaction mechanisms between the liquid phase and mixer geometry remain inadequately understood. In this study, a bidirectional coupled discrete element method–smoothed particle hydrodynamics approach is employed to simulate both dry and wet mixing of particles with three distinct densities in a blade-type mixer. A full-factorial numerical experimental design is implemented to systematically assess the influence of the blade length-to-shell radius ratio (L/R) and the number of blades on mixing performance. Results reveal that at a low L/R ratio (L/R = 0.6), insufficient moment transfer to the fluid phase fails to counteract sedimentation, thereby exacerbating the settling of high-density particles. At higher L/R ratios (L/R = 0.8 and 0.9), the liquid phase effectively suppresses density-driven segregation during the sedimentation stage by suspending particles, thereby maintaining a well-mixed state with comparatively stable performance. This work elucidates the intricate coupling among mixer geometry, fluid dynamics, and granular flow, offering mechanistic insights and practical guidance for the rational design of anti-segregation mixing equipment.