DEM Study on the Segregation of a Non-Spherical Intruder in a Vibrated Granular Bed

The segregation process of a single large intruder in a vibrated bed of small particles has been widely studied, but most previous studies focused on spherical intruders. In this work, the discrete element method was used to study the effects of vibration conditions and intruder shape on the dimensionless ascending velocity (v(a)) of the intruder. The intruder was in a prolate shape with aspect ratio varied but its equivalent diameter fixed. Three equivalent diameters, namely volume-equivalent diameter, surface-area-equivalent diameter, and Sauter diameter, were used. It was found that v(a) increases and then decreases with the rise of the dimensionless vibration amplitude (A(d)) and the dimensionless vibration frequency (f(d)), and v(a) increases with the decrease of the sphericity of the intruder (phi). Moreover, the porosity variation in the vibrated bed and the granular temperature were analyzed, which can be linked to the change of v(a). It was further found that v(a) can be uniformly correlated to A(d)center dot fd0.5, while the critical change of the response of v(a) to A(d) and f(d) occurs at Gamma = 4.83, where Gamma is the vibration intensity. Based on these findings, a piecewise equation was proposed to predict v(a) as a function of A(d), f(d), and phi.

Automated summary

The study utilized the discrete element method to investigate the segregation process of a single large intruder in a vibrated bed of small particles, focusing on the effects of vibration conditions and intruder shape on the intruder's dimensionless ascending velocity. It was found that the ascending velocity changes with the variation of vibration amplitude and frequency, and is influenced by the shape of the intruder.