Dense flows of bidisperse assemblies of disks down an inclined plane
Résumé
Using molecular dynamics simulations, we have studied the flow down a rough inclined plane of a bidisperse assembly of frictional cohesionless disks, characterized by the size ratio and the proportion of large grains. We have restricted our study to steady uniform flows, once a stable segregation has developed inside the flowing layer. The material is segregated in three layers : a basal layer made of small grains, a superficial layer made of large grains, and a mixed layer in the center. In a certain range of parameters of the mixture, this structure leads to a localization of the shear near the rough bed. Moreover, like for slightly polydisperse assemblies, we measure an approximately linear increase of the effective friction as a function of the ratio of the Froude number and the height of the flowing layer. We compare those results with the prediction of a simple two-layer model.