Saltation flow measurements relating to modeling of snowdrifting

Abstract

In scale-model studies of snowdrifting phenomena the similarity requirements cannot all be satisfied. The question of which of the conflicting requirements should be satisfied reduces to one of whether low-density or high-density particles should be used to simulate the snow. Experiments aimed at resolving this question are reported. Wind-tunnel experiments involving saltation of low-density (specific gravity 0.16) and high-density (specific gravity 2.7) particles were carried out. Velocity profiles, particle transport rates and “snowdrift” shapes produced by model snowfences were measured and compared with field data. The results show that when using the low-density particles the saltation process is not dynamically similar to that in actual snowdrifting; important differences in snowdrift shape and particle transport rates occur. The lack of similarity apparently stems from aerodynamic lift forces which are not negligible in comparison with the weight of the low-density particles. The use of high-density particles is recommended when modeling snowdrifting phenomena.