Author(s): Taka-Aki Okamoto; Iehisa Nezu; Aki Katayama
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Keywords: LIF; PIV; Concentration; Coherent eddies; Submerged vegetation flow
Abstract: rivers and the submerged vegetation has the potential to improve water quality. Submerged vegetations reduce suspended sediment transport because of the local reduction in the bed shear stress. Coherent turbulent motions are generated near the vegetation edge and these large-scale coherent eddies control the vertical exchange of mass and momentum between the over-and within canopies. It is therefore important for river management to investigate hydrodynamic characteristics and coherent eddies in open-channel flows with vegetation canopies. In the present study, continuous dye-injection experiments were conducted to evaluate the vertical mass transport in open-channel flow with rigid vegetation models by changing the vegetation density. A combination technique between particle image velocimetry (PIV) and planar laser-induced fluorescence (LIF) was developed to measure the turbulent diffusion property and the coherent motions simultaneously.
Year: 2010