Search for a command to run...
Powder snow avalanches are highly turbulent, dilute suspensions clouds moving down steep slopes due to their buoyancy. The motivation for the present research was, on the one hand, to improve our knowledge of the effect of snow entrainment, by the avalanche, from the snow layer and, on the other hand, to develop an improved theoretical model of avalanche dynamics. The theoretical model presented in this thesis includes large density difference effects and demonstrates the importance of snow entrainment on the avalanche velocity. The model is in good agreement with recent measurements of the front velocity of an avalanche. The parameters in the model, such as the shape and spatial growth rate of the clouds, were determined from laboratory experiments, conducted with saline and suspension clouds, in a flow regime close to that of avalanches. A theoretical extrapolation of these parameters (obtained in the Boussinesq limit) to large density difference clouds (avalanches) is proposed. Laboratory experiments with sediment entraining clouds indicate the trend sediment entrainment has on the avalanche velocity. A presentation in terms of dimensionless variables of avalanche velocities and that of laboratory clouds shows clearly the similarities and differences between the two.