On the vortex formation in the mixing layer behind dunes

摘要

Flow processes in the mixing layer behind dunes provide the feedback between flow, sediment transport and the bed forms, which is assumed to be responsible for the development and persistence of dunes. It is attempted to classify these flow processes in terms of coherent structures, in which the vorticity of the upstream boundary layer is concentrated. Information from flow visualization is used to describe these vortical structures. The literature was reviewed to search for theoretical and experimental results of similar flow situations, which can provide the essential concepts.