Parameter calibration and mixing uniformity of irregular gravel materials in a rotating drum

In the study of the mixing processes of gravel materials by using the discrete element method, an appropriate selection of physical and contact parameters is crucial. In this study, the physical parameters of irregular gravel were obtained by performing a series of experiments, and the contact parameters were determined using the response surface method. In addition, the V-box experiment was designed to verify the rationality of the parameters. Furthermore, the mixing processes of gravel materials in a rotating drum with different cylindrical rod structures at the same rotational speed and filling degree were simulated, and the number of contacts between particles was used to quantitatively characterize the mixing uniformity. The simulation results revealed that cylindrical rods greatly improve the mixing uniformity; the effect is the best when the cylindrical rod distance is twice the maximum particle size. Fig. 1. Contact number rates of particles with different cylindrical rod diameters. Fig. 2. Effect of particle size on mixing uniformity. [Display omitted] •Calibrating parameters of particle model by combining experiments and simulation.•The mixing degree of particles can be improved by adding rods into the drum.•The diameter of cylindrical rods has little effect on particles mixing degree.•The smaller the distance between the rods, the better the mixing degree.