Modeling dam break granular flows

In this paper a dry granular dam break phenomenon is investigated comparing experimental and numerical results. The experiments were performed reproducing the sudden collapse by the retaining wall of dry grains of sand in a rectangular horizontal channel with different initial dam height values. A depth-integrated two-phase flow model, developed for sediment transport in fluid flows in unsteady conditions, is used for simulating the experiments. In particular, the investigation is focused on how to reproduce the effect of resistive forces on a dam break granular flow. The proposed model accounts for sediment particles collisional shear stress through a kinetic scheme and frictional stress through a Coulomblike behavior. The comparison between numerical model prediction and experimental evidence show a very good agreement of the front position development and an enough reproduction of the free surface profiles. These results demonstrate that the considered model, even if developed for sediment transport in fluid flows, is able to reproduce with a unified approach also the dry granular material behavior. Moreover, the results show that expressing the resistance as sum of both collisional and frictional stresses is a good option for modeling dry granular dam break phenomena with a depth integrated continuum approach.