Effects of size polydispersity on segregation of spherical particles in rotating drum

Abstract

To get insight into the segregation process of a polydisperse granular materials flow, we numerically investigated the migration process of particles in a rotating drum operating in the rolling regime by means of the discrete element method. Particle migration is analyzed through the variation of the proportion of particles in different zones where the flow property is characterized. The proportion of particles in different zones of the drum shows to increase in the center of the flow radially and axially where a higher concentration of small particles is observed, while its decreases in other zones with a higher concentration of larger particles. Interestingly, we find that the migration process of particles leads to radial and axial segregation which is caused by a combination between the exerted fluctuation forces on particles and its surrounding pressure gradient.

Gravity-driven wet granular free-surface flows down an inclined plane: Effects of the inclination angle

“…In DEM, all particles are assumed to be rigid, and each particle interacts with others via the frictional elastic force laws [24,25]. The solid interaction forces involve the normal contact forces and the tangential contact forces [21,22,24,26]. These normal and tangential forces are proportional to the relatively normal and tangential displacement obtained by using the stepping integration based on the Newton second law [21,22,24,27,28].…”

Effects of the size polydispersity and friction coefficient on the compressive strength of wet granular materials

“…The interactions between two primary particles i and j involve the normal contact forces f n , the tangential contact forces f t , and capillary cohesion forces f c [30], as shown in Fig. 1, where f n is obtained by considering the normal elastic and normal damping components, f t is determined by the Coulomb friction law [21], and the capillary cohesion force f c is proportional to the cohesion pre-factor κ = 2πγ s , where γ s denotes the liquid-vapor surface tension [30]. The preparation and simulation of this current work involve three different stages: 1) creating assemblies of primary particles with different size polydispersities by using an isotropic compression; 2) extracting granules by applying a spherical probe into the packings of primary particles; 3) applying a constant downward velocity on the top platen to compress the granules.…”

“…Over the last few decades, the effects of the size polydispersity and the friction coefficient on the behavior of granular materials have been investigated, especially the segregation, mechanical strength, and the rheological properties [11,[14][15][16][17][18][19][20][21]. The increase of the size polydispersity and friction coefficient leads to increase the size segregation of granular materials in different configurations [17,[21][22][23][24]. In contrast, the size polydispersity and the friction coefficient of grains represent different effects on the rheological properties of granular materials in the steady flowing state.…”