B. Guo, L. Li, X. Ma
In order to separate rice and straws in dustpan and reveal its segregation mechanism, the discrete element method is used to establish the mathematical models of rice and straws and the dynamic behaviour of binary mixed system (rice and straws) under horizontal vibration is simulated. The results show that rice and straws in dustpan present apparent stratification in the vertical direction and straws are located above rice. The comprehensive application of kinetic energy theorem, theoretical mechanics, and fluid mechanics can provide a reasonable explanation for the segregation mechanism. The volume concentration of rice is used to quantify the degree of segregation. During the study, the problem of low energy in some areas of the system is found, together with the existence of convective rolls formed by mixed particles in motion, which result in an incomplete segregation of rice and straws, and the volume concentration of rice obtained is 0.87. By adding transverse ribs on the bottom plate and the arc wall of the dustpan, the micro-vibration of the bottom particles is enhanced, the system energy is increased, and the convective rolls are eliminated, and finally the volume concentration of rice obtained is close to 1. The influences of frequency and amplitude on layering effect are discussed and the method of selecting best vibration parameters is indicated. In the end, the experiment is designed and conducted, demonstrating that DEM is an effective method to simulate and analyse granular segregation.
Discrete element method, Dynamic behaviour, grain segregation, Granular Matter, Horizontal vibration