Aeolian saltation threshold: the effect of density ratio



Saltation threshold data from three wind tunnels and from hydraulic flumes are presented to show that the dimensionless threshold friction speed for small particles is a continuous function of particle-to-fluid-density ratio. In addition, the dimensionless threshold speed is a function of the grain-friction Reynolds number and an interparticle force term. The variation with density ratio seems to be due to the relative energy with which particles impact other particles to initiate saltation.