Drag Partition and Its Possible Implications for Dust Emission

The mechanisms for dust emission involve the saltation of sand-sized particles and the transfer of momentum from the atmosphere to the surface. Roughness elements on aeolian surfaces influence the transfer of momentum through the partition of total momentum flux into a pressure drag on roughness elements and a skin drag on substrate surface. The objective of this study is to better understand the mechanisms for momentum transfer over rough surfaces and drag partition, so that better dust-emission parameterization schemes can be developed. A large-eddy simulation model is implemented for the purpose. We perform computational simulations of turbulent flows over individual and arrays of roughness elements. Further, we examine how roughness elements affect drag partition and dust emission. The results lead to a possible new concept of dust emission over rough surfaces.