含柔性沉水植物明渠水流运动特性试验研究

采用激光多普勒流速仪(LDV)试验研究含柔性沉水植物的水流运动。试验结果表明:流速沿垂线分布呈S形,分为3个区域,即植物内部区、过渡区和上部区。植物密度对过渡区内流速影响显著,在该区内,植物密度越大则流速梯度越大。含植物水流的紊动强度和雷诺应力都明显增大,它们在垂线分布上有相似之处,都是在植物顶层的位置上达到最大值,说明在此区域内存在较强的能量交换和剪切作用;二者在植物顶层上部区域随着水深的增加而减小,在植物内部区随着水深的增加而增大。

Experimental study on flow characteristics of open channels with submerged flexible vegetation

Laboratory experiments using LDV were performed to investigate the characteristics of water flow in open channels with submerged flexible vegetation.Test results reveal that the measured velocity distribution,which is S-shaped,can be divided into 3 areas: the internal area,the transition area and the upper area of vegetation.The flow velocity in the transition area is evidently affected by vegetation density,and the velocity gradient tends to increase with the vegetation density.It is also concluded that the turbulence intensity and Reynolds stress greatly increase in water flow with vegetation,and the two parameters increase with flow depth in the internal area and decrease with flow depth at the top layer of vegetation.The maximum values of these two parameters occur near the top of the vegetation,showing that copious energy exchange and powerful shear action exist in this area.