Discrete element method simulation of rice grain motion during discharge with an auger operated at various inclinations

Abstract

This paper aims to effectively evaluate the efficiency and conveying characteristics of different unloading angles. The movement characteristics of rice grains in the unloading auger were studied from the perspective of particle dynamic behaviour. A discrete element model was constructed, and numerical simulation carried out. The results showed that the voids ratio between particles with an inclination of −30° decreased gradually with increasing axial distance of auger. The voids ratio between particles with an inclination of −15° - 30° at first remained unchanged but then increased gradually with increasing axial distance of auger. The maximum average velocity of grain flow with −30°, −15°, +15° and +30° inclinations occurred in regions close to the inlet and the outlet of the auger. The axial flow performance decreased with increasing unloading angle and moisture content of rice. The axial flow of grain with different angles and moisture contents conformed to the “super” diffusion (mean square deviation ∝ t 2 ). In addition, the conveying characteristics of particle flow in different regions from the perspective of particle force and kinetic energy were explored. • Grain voids ratio distribution with different unloading angles explored. • Grain velocity fluctuation characteristics with different unloading angles studied. • Mechanism velocity change analysed from the aspect of force and energy. • Conveying law with different angles and moisture content compared.