Contribution of theoretical and experimental results to powder-snow avalanche dynamics

A powder-snow avalanche can be considered as the flow of a turbulent buoyant volume of heavy fluid (air-snow suspension) in an ambient fluid, the air. In the dynamics of such a flow, two mechanisms must be taken into account: the air entrainment and the snow entrainment inside the avalanche. From fluid mechanics equations (mass conservation and momentum equations) formulae were obtained giving velocity and density of the avalanche as a function of the slope path, the growth rate of the avalanche and fresh snow-cover characteristics. On the other hand, laboratory simulations gave (among others) experimental results about the growth rates of buoyant clouds. From these theoretical and experimental studies, practical examples are proposed with given path profiles and snow-cover characteristics. Such examples can be generalised to any other cases.