Segregation and mixture profiles in dense, inclined flows of two types of spheres

Abstract

We study dry flows of two types of spheres down an inclined, rigid, bumpy bed in the absence of sidewalls. The flow is assumed to be steady and uniform in all but the direction normal to the free surface, collisions between particles are dissipative, and the sizes and masses of the particles are not too different. We restrict our analysis to dense flows and use an extension of kinetic theory to predict the concentration of the mixture and the profile of mixture velocity. A kinetic theory for a binary mixture of nearly elastic spheres that do not differ by much in their size or mass is employed to predict profiles of the concentration fraction of one type of sphere. We also determine the ratio of the radii and of the masses of the two species for which there is no segregation. We compare the predictions of the theory to the results of numerical simulations.

Particle-size segregation in dense granular avalanches

“…However, it is not yet clear that it can fully explain the rise of large particles to the surface of an avalanche in chute flow [75], where high granular temperatures develop near the base of the flow [64] rather than at the surface. If the kinetic stresses do turn 100 out to be the critical driving forces for segregation then it will be necessary to compute them as part of the solution for the bulk flow [76], which significantly complicates the model.…”

Debris flows: Experiments and modelling

“…However, it is not yet clear that it can fully explain the rise of large particles to the surface of an avalanche in chute flow [75], where high granular temperatures develop near the base of the flow [64] rather than at the surface. If the kinetic stresses do turn out to be the critical driving forces for segregation then it will be necessary to compute them as part of the solution for the bulk flow [76], which significantly complicates the model. Gray and Ancey [44] showed that it is possible to generalize the bidisperse model to any number of discrete grain-size classes.…”

“…J.M.N.T. Gray et al / C. R. Physique 16 (2015) [73][74][75][76][77][78][79][80][81][82][83][84][85] jacente de grains statiques ou en déplacement lent. La combinaison de la ségrégation et des changements de phase solide-fluide granulaire crée des motifs complexes dans les dépôts résultants, mais la compréhension complète de ces effets est pour le moment hors de portée.…”

Modelling size segregation of granular materials: the roles of segregation, advection and diffusion

“…Recently Larcher & Jenkins (2013) extended kinetic theory to predict segregation of binary granular mixtures in dense flow and obtained qualitative agreement with discrete element method (DEM) simulations, but a first-principles based theory capable of quantitatively predicting segregation for dense flow is still lacking. In the meantime, a broad theoretical framework for segregation-driven pattern formation in dense flows is emerging (Gray & Thornton 2005;Gray & Chugunov 2006;Thornton et al 2006;May et al 2010;Wiederseiner et al 2011;Marks et al 2011;Thornton et al 2012;Kowalski & McElwaine 2013).…”