Motion behaviour of ellipsoidal granular system under vertical vibration and airflow

Abstract

We studied the motion behaviour of ellipsoid particles under vertical vibration and airflow. Three typical convection patterns were observed when submitted to vertical vibration with frequency (f) from 20 Hz to 80 Hz and dimensionless vibration acceleration (Γ) from one to six. We studied the effects of f and Γ on the change of convection patterns. We quantitatively studied the effects of f, Γ, airflow direction, airflow velocity, and particle shape on the convection area and intensity using the area fraction λ and average velocity vz characterizing the convection area and intensity, respectively. Results showed that the convection first occured occurred in the upper part of the granular system. Increasing f and A can both increase the convection area and strengthen the convection intensity. A had a greater influence than f at the same Γ. The wheat particles were more likely to enter the global convection state under the action of the airflow in the opposite direction of gravity. The maximum convection intensity of wheat particles under the airflow in the opposite direction of gravity was approximately 30-35% of the value measured under the airflow along the direction of gravity. The convection area and maximum convection intensity of the spherical particles were approximately 85% and 93% of the measured values for the ellipsoidal particles, respectively. We also analysed the effects of f, Γ, airflow direction, airflow velocity, and particle shape on the convection area on the basis of energy dissipation.