Dense granular flow of mixtures of spheres and dumbbells down a rough inclined plane: Segregation and rheology

Abstract

We study the flow of equal-volume binary granular mixtures of spheres and dumbbells with different aspect ratios down a rough inclined plane, using the discrete element method. We consider two types of mixtures -in the first type the particles of the two species have equal volume but different aspect ratios (EV) and in the second type they have variable volumes and aspect ratios (VV). We also use mixtures of spheres of two different sizes (SS) with the same volume ratios as in the mixtures of the second type, as the base case. Based on the study of Guillard, Forterre and Pouliquen [J. Fluid Mech. 807, R1-R11 (2016)], the inclination angle of the base for each mixture is adjusted and maintained at a high value to yield the same pressure and shear stress gradients for all mixtures and a high effective friction (µ) for each. This ensures that the segregation force and resulting extent of segregation depend only the size and shape of the particles. The species with larger effective size, computed in terms of the geometric mean diameter, floats up in all cases and the dynamics of the segregation process for all the mixtures are reported. The concentration profiles of the species at steady state agree well with the predictions of a continuum theory. The µ − I and φ − I scaling relations, where I is the inertial number and φ is the solid volume fraction, extended to the case of mixtures, are shown to describe the rheology for all the cases.

Experimental Study of Mixing of Nonspherical Particles in a Vibrated Packed Bed Mixer

“…Limited studies have considered nonspherical particles; however, in the last decade, there is an increased focus on the study of nonspherical particles. The shape of particles plays a significant role in the mixing and segregation processes. − For example, by experimental and numerical techniques, Vollmari et al investigated the effect of nonspherical particles (cuboid) on the mixing quality in monodisperse and bidisperse systems. They found that monodisperse plates ( t = 1.34 s) show the fastest mixing to reach a mixing index value of 0.5 compared to cubes ( t = 1.88 s) and elongated cuboids ( t = 2.04 s).…”

Particle Size Segregation in Granular Mass Flows With Different Ambient Fluids

“…Granular flows comprising particles of different sizes (Savage & Lun, 1988), shapes (Mandal & Khakhar, 2019; Zhao et al, 2018), and densities (Tripathi & Khakhar, 2013; Tunuguntla et al, 2014) have a tendency to segregate according to these species properties. Understanding and predicting segregation is relevant to processes where separation of different species may be either desired or avoided (Fan et al, 2014).…”

DEM Modelling of Segregation in Granular Materials: A Review

“…Parameters from literature. Many DEM studies on segregation have taken either all or merely a selection of the parameters from the literature (Asachi et al, 2021;Chibwe et al, 2020;Cliff et al, 2021;Hong et al, 2021;Ketterhagen et al, 2007Ketterhagen et al, , 2009Ketterhagen and Hancock, 2010;Kou et al, 2013Kou et al, , 2015Kou et al, , 2018Kou et al, , 2019Liao et al, 2023;Mandal and Khakhar, 2019;Tian et al, 2022;Wu et al, 2013;Xu et al, 2018bXu et al, , 2021You et al, 2016;Yu et al, 2018;Yu and Saxén, 2010, 2012Zhang et al, 2021;Zhao and Chew, 2020a). This approach has the same shortcoming as the previous group, since the parameters are obtained from resources that have not conducted calibration.…”