A conceptual model for sheet-flow drawn from rapid granular flow theories

This paper is aimed at presenting i) a simple, yet sound, conceptual model ap-plicable to the simulation of erosion, deposition and transport of cohesionlesssediment in stratified flows under high shear stresses and ii) numerical solutionsin idealized unsteady flow non-equilibrium transport situations. The conceptualmodel for the granular phase comprises 2DV mass and momentum and energyequations and constitutive equations, all derived within the dense limit of theChapman-Enskog kinetic theory. 1D shallow-flow conservation and closure equa-tions are derived for the fluid-granular mixture. Formulas for the average velocityin the transport layers, the vertical net flux of sediment mass and the thickness ofthe transport layer are thus obtained. Numerical solutions for dam-break flowsover cohesionless mobile beds in prismatic and non-prismatic channels are ob-tained and discussed.