Numerical simulation of drifting snow: erosion and deposition models

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 Listen 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 laver as a boundary condition. For the flow, and for the suspension, we adopt the same model as that of Uematsu and Listen. For mass exchange between the flow and snow surface, we have developed an erosion-deposition model where mass exchange is defined in relation to flow turbulence, threshold-friction 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 results. The main results of the various sensitivity experiments are: the leeward accumulation is very sensitive to the ratio (mu*/mu*(t))(it appears for (mu*/mu,(t)) close to 1 and disappears for (mu*/mu*(t)) > 1.2), the global accumulation produced by the fence increases as (mu*/mu*(t)) decreases and the back reaction of particles on turbulence extends slightly the windward accumulation.