有植被河道的水力特性研究

Hydraulic characteristic of river channels covered with vegetation

利用三维超声波多普勒流速仪(ADV)量测有植被时水槽不同测点位置的瞬时流场。分析了测点位置和水深与植被高度比对时均流速分布的影响。试验结果表明植被层上下水流结构复杂,柔性植被的存在使垂线流速降低,所测得的流速分布在植被层顶部附近呈现“<”形状,在植被区域内部流速分布近似为“3”形。分析了植被区水流紊动强度和雷诺应力的垂线分布情况。水流紊动强度和雷诺应力在植被区域的上层相对较大,说明在该处发生着剧烈的质量和动量交换以及很强的剪切作用。

A 3D acoustic Doppler velocimeter （ADV） is used to measure the instantaneous flow fields at different measurement points in a flume covered with vegetation. The influences of locations of measurement points and the ratio of the water depth to the height of vegetation on the distribution of time average flow velocity are analyzed. Some conclusions are drawn： the flow structure is complicated in the layer of vegetation; the existence of flexible vegetation decreases the flow velocity in vertical direction; the flow velocity distribution calculated near the top of the vegetation layer shows a＂ 〈 ＂-shape and it demonstrates a ＂3＂-shape within the region of vegetation. Moreover, the distributions of turbulence intensity and Reynolds stress of water flow in the vertical direction in the region of vegetation are analyzed, and the result shows that they arc relatively large in the upper layer of this region, demonstrating that fierce quality and momentum exchange and high shear stress occur at this region.