Basal Effect in Mono- and Bi-Disperse Chute Flows

Abstract

The basal condition for granular chute flows is assumed rough and non-slip in experimental and numerical studies. In mono-disperse flows, a rough base is usually constructed by gluing/fixing a layer of particles that is similar or identical to the flowing particles. However, the base condition is not so clear in bi-disperse flows, where size segregation changes the relative basal roughness. In this paper, basal effect is studied in both mono- and bi-disperse chute flows. Different size ratios are adopted to understand how size segregation affects the basal condition and velocity profile in the steady, fully developed state. It is found that considerable sliding may arise as large particles stay in contact with the base, and it may affect the development of segregation. The velocity profile at the steady state is different due to the occurrence of segregation. In addition, sensitivity analyses show that the basal effect is independent of the sample size and contact parameters.