Flow structure over a wavy bed with vegetation cover

• 作 者: Fazeleh Kabiri Hossein Afzalimehr Jueyi Sui
• 机 构: Department of Water Engineering,Isfahan University of Technology,Environmental Engineering Program,U
• 出 处: International Journal of Sediment Research
• 发表日期: 2017年02期
• 关键词: Wavy bed Vegetation cover Turbulence Flow separation Gravel

On the basis of experiments carried out in flume with a wavy bed with vegetation cover,flow velocity,turbulence intensities and Reynolds stress distributions are investigated.The wavy bed was similar to dune in this study.The fixed artificial dunes were constructed over the bed and artificial vegetation put over them in a laboratory flume.An Acoustic Doppler Velocimeter and spatially-averaged method were applied to determine turbulent flow components and shear velocity.Results were compared with a gravel bedform.It was observed that vegetation cover influences considerably the flow structure and displays clearly the flow separation and reattachment point.The law of the wall was not valid within the vegetation cover,but it was fitted well to the zone above the vegetation cover within the inner layer.For a wavy bed having the same dimensions,shear velocity and friction factor over vegetation cover are 1.7 and 2.6 times of those for the gravel bedform,respectively.The results of laboratory study were compared with those of river study.

On the basis of experiments carried out in flume with a wavy bed with vegetation cover, flow velocity, turbulence intensities and Reynolds stress distributions are investigated. The wavy bed was similar to dune in this study. Fixed artificial dunes were constructed over the bed and artificial vegetation put over them in a laboratory flume. An Acoustic Doppler Velocimeter and spatially-averaged method were applied to determine turbulent flow components and shear velocity. Results were compared with a gravel bedform. It was observed that vegetation cover influences that the flow structure and displays clearly the flow separation and reattachment point. The law of the wall was not valid within the vegetation cover, but it was fitted well to the zone above the vegetation cover within the inner layer. For a wavy bed having the same dimensions, shear velocity and friction factor over vegetation cover are 1.7 and 2.6 times of for the gravel bedform, respectively. The results of laborator y study were compared with those of river study.