Coherent Structures in the Flow over Two-Dimensional Dunes
The fluid flow over rough sand beds in rivers has unique dynamics compared with the flows that occur when the bed is flat. Depending on the flow Reynolds number, the most commonly found river-bed formations are ripples and dunes. Ripples have dimensions much smaller than the river depth, while dunes may reach heights of the order of the depth. Ripples do not affect the dynamics of the whole flow depth whereas dunes influence on the turbulent flow as well as the sediment transport at the whole depth. Dune formation may affect navigation, erosion of bridge piles and other structures, as well as dispersion of contaminants (Itakura and Kishi, 1980).
KeywordsSediment Transport Coherent Structure Horseshoe Vortex Vortex Loop Dune Crest
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