The saltation model for roughness surface incorporating effect of free wind velocity over boundary layer
Two previous saltation models for roughness surface focus on effect of aerodynamic roughness length on sand transport rate,disagreement with recent investigations which find that such the factor as free wind veloci-ty over boundary layer also affects significant saltation flux.Thus,saltation fluxes under various free velocities over 9 roughness surfaces were observed in a blown-sand wind tunnel to develop new model,including the 6 sand surfaces covered with compact roughness elements,and the 3 sand surfaces with porous elements.We find that there exists a significant gap between the observed and computed saltation fluxes by the traditional mod-els,and that the new saltation model is better since it incorporates the ensemble effects of roughness length,free wind velocity and the modified wind friction(function of wind friction threshold velocity and wind friction veloc-ity)on saltation.The effect of free wind velocity on saltation flux could be related with the variation of total shear stress over roughness surface with height.
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