Analytical Solution of Collisional Sheet Flows

We analyse the sediment transport that is dominated by collisional exchange of momentum between the particles and can be identified as the transition regime between bed and suspended load on the basis of a recent theory proposed by Berzi (2011). He accounts for the role of the interstitial fluid on particle collisions; in doing so, he distinguishes three regions: one dilute diffuse layer neighbouring the free surface where binary collisions mainly characterize the particle interactions; one dense layer, where correlated motion between the particles plays an important role in the collisional exchange of momentum; one macro-viscous-layer, close to the erodible bed, where the momentum exchange is dominated by the fluid viscous forces. Here, we use that theory to obtain the particle flow rate and the distributions of velocity and concentration along the cross-section of the flow to be compared with existing experiments.