| Summary: | International audience Earlier works on numerical modelling are analysed. Anderson and Haff (1991) proposed a model using the " splash function " which was defined for cohesionless sand. The Uematsu and others (1989,1991) and Liston and others (1993,1994) approaches are based on fluid-mechanics conservation laws where the snow is transported and diffused by the air flow. These models consider the saltation layer as a boundary condition. For the flow, and for the suspension, we adopt the same model as that of Uematsu and Liston for the mass exchange between the flow and snow surface, we have developped an erosion-deposition model were the mass exchange is defined in relation to flow turbulence, threshold velocity and snow concentration. Our snow-erosion model was calibrated using Takeuchi's (1980) field measurements. The deposition model was tested by comparing numerical results with wind-tunnel ones, for sawdust-accumulation windward and leeward of a solid snow fence with a bottom gap. The numerical results obtained are close to the experimental data. The main results of the various sensitivity experiments are : the leeward accumulation is very sensitive to the ratio (u*/u*t) (it appears for u*/u*t and disappears for u*/u*t > 1,2), the global accumulation produced by the fence increases as u*/u*t decreases and the back reaction of particles on turbulence extends slightly the windward accumulation. Des ouvrages précédents sur la modélisation numérique sont analysés. Anderson and Haff (1991) ont proposé un modèle utilisant la "fonction splash" qui a été définie pour le sable non cohérent. Les méthodes de Uematsu et al (1989, 1991) et les méthodes de Liston et al (1993, 1994) sont basées sur les lois de conservation de la mécanique des fluides où la neige est transportée et diffusées par le débit d'air. Ces modèles considèrent que la couche de saltation est une condition limite. Pour l'écoulement et pour la suspension, nous adoptons le même modèle que celui de Uematsu et de Liston. Pour l'échange massique ...
|
|---|