Author(s): Taka-Aki Okamoto; Iehisa Nezu
Linked Author(s):
Keywords: PIV; PTV; Monami phenomena; Flexible vegetation; Coherent vortex
Abstract: Turbulence structure in natural rivers is often affected by the presence of vegetation zone. The large-scale coherent vortex is generated predominantly in the shear layer near the top of canopy. These organized vortices may have an essentially important relation with the waving motions of flexible vegetations, which is called here as the‘‘Monami’’. The strong oscillations in canopy geometry have the effects of decreasing the amount of vertical turbulent momentum and mass transport into the aquatic canopies. However, any important relation between the “Monami’’phenomena and the instantaneous turbulence structure is not yet available. Therefore, in the present study, we highlighted these important topics and measured the instantaneous velocity structure and coherent motions in open-channel flows with flexible vegetations by using a combination of PIV&PTV techniques.
Year: 2010