Numerical Simulations of Dense Clouds on Steep Slopes:

Abstract

In this paper two-dimensional Direct Numerical Simulations (DNS) of dense clouds moving down steep slopes are presented for the first time. The results obtained are in good agreement with the overall characteristics -- that is, the spatial growth rate and velocity variations -- of clouds studied in the laboratory. Direct numerical simulations give, in addition to the overall flow structure, local density and velocity variations inside the cloud, not easily accessible in experiments. The validity of two-dimensional simulations as a first approach is justified by the dynamics of the flow and by comparison with experimental results. The interest of the results for powdersnow avalanches is discussed, concluding that two-dimensionality is acceptable and that large density di#erences need to be taken into account in future simulations