Author(s): Taka-Aki Okamoto; Iehisa Nezu
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Keywords: Organized vortices; Submerged vegetation; Open-channel flow; Lateral heterogeneity; LES
Abstract: Aquatic plants are fundamental components of natural water environment in rivers and wetlands. Vegetation induces additional flow resistance and reduces suspended sediment transport because of the local reduction in bed shear stress. In such vegetated open-channel flows, large-scale coherent vortices are generated near the vegetation edge and govern the mass and momentum exchanges between the within-canopy layer and the over-canopy layer. It is very important for river environment to reveal hydrodynamic characteristics near the vegetation zone. Therefore, in the present study, 3-D large eddy simulation (LES) was conducted in vegetated open-channel flows, in which the vegetation elements are involved exactly in calculations by the use of non-slip boundary condition, without any assumption of drag coefficient C D. The present study revealed the relation between large-scale coherent vortices and 3-D flow structure in submerged vegetated open-channel flows.
Year: 2010