Flow and Transport in Regions with Aquatic Vegetation
نویسنده
چکیده
1 This paper describes mean and turbulent flow and mass transport in the presence of aquatic 2 vegetation. Within emergent canopies, the turbulent length-scales are set by the stem diameter and 3 spacing, and the mean flow is determined by the distribution of canopy frontal area. Sparse 4 submerged canopies enhance bed roughness and near-bed turbulence, but the velocity profile 5 remains logarithmic. For dense submerged canopies, the drag-discontinuity at the top of the canopy 6 generates a shear-layer, which contains canopy-scale vortices that control the exchange of mass and 7 momentum between the canopy and the overflow. The canopy-scale vortices penetrate a finite 8 distance into the canopy, δe, set by the canopy drag. This length-scale segregates the canopy into 9 two regions: the upper canopy experiences energetic turbulent transport, controlled by canopy-scale 10 vortices, while the lower canopy experiences diminished transport, associated with the smaller stem11 scale turbulence. Flexible blades move in response to the canopy-scale vortices, called monami. 12
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