Abstract
In this work we present a model for granular flows saturated with water and driven by gravity, which is therefore well suited to the modeling of debris flows. These phenomena are treated with a two-phase approach. In particular in the case of interest for this work the liquid phase is water, while the solid phase is treated as a granular flow. The mechanics of granular flows depends on the type of contact among the particles. In this respect it is possible to identify two different regimes. The collisional regime occurring when the contacts are nearly instantaneous while the frictional regime occurs when the contacts are long lasting. The proposed model is based on the experimental evidence that the two regimes coexist across the flow depth. We adopted the kinetic theory for a dense gas to model the collisional regime, while we used a new rheological formulation and a new equation of state for the frictional regime, according to Armanini et al. (2014). In particular, in this paper, we enhance the issue of the contribution to the dissipative process due to fluctuations in the drag forces. © 2014 Taylor & Francis Group, London.