The hydraulic characteristics in an open channel with vegetation are very important in controlling the environment pollution and restoring the river ecology. This paper studies the influence of the bed form and the vegetation patch density on the spatial velocity pattern. Rigid fiberglass circular cylinders are used to simulate the vegetation and a 3-D acoustic Doppler velocimeter (ADV) is used to measure the local flow velocities. Two types of bed forms and a series of vegetation patch densities are considered. The experimental results show that the bed form significantly influences the vertical distribution of the streamwise velocity. Besides, the velocity is affected by the bed form while the lateral distribution shape of the streamwise velocity as well as the lateral and longitudinal distribution shapes of the depth-averaged velocity is less affected. When all test conditions but the bed condition remain the same, as a result of the water energy consumption by the sediment movement, the velocity in the mobile bed case is smaller than that in the rigid bed case. The vegetation patch density has a significant effect on the flow velocity. The distributions of the flow velocity at different locations show different trends with the increase of the vegetation patch density. The upstream adjustment length is not affected by the vegetation patch density, but the steady wake length is very much affected.

中文翻译：

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带有植被斑块的刚性和流动通道中的速度模式

植被露水的水力特性对于控制环境污染和恢复河流生态非常重要。本文研究了床形和植被斑块密度对空间速度格局的影响。刚性玻璃纤维圆柱体用于模拟植被，而3-D声多普勒测速仪（ADV）用于测量局部流速。考虑了两种床型和一系列植被斑块密度。实验结果表明，床的形态对流向速度的垂直分布有很大影响。除了，速度受床形的影响，而水流速度的横向分布形状以及深度平均速度的横向和纵向分布形状影响较小。当除床条件外的所有测试条件保持不变时，由于沉积物运动消耗的水能，移动床壳中的速度小于刚性床壳中的速度。植被斑块密度对流速有显着影响。随着植被斑块密度的增加，不同位置的流速分布呈现出不同的趋势。上游调节长度不受植被斑块密度的影响，但是稳定尾迹的长度会受到很大影响。由于沉积物运动消耗水能，移动床箱中的速度小于刚性床箱中的速度。植被斑块密度对流速有显着影响。随着植被斑块密度的增加，不同位置的流速分布呈现出不同的趋势。上游调节长度不受植被斑块密度的影响，但是稳定尾迹的长度会受到很大影响。由于沉积物运动消耗水能，移动床箱中的速度小于刚性床箱中的速度。植被斑块密度对流速有显着影响。随着植被斑块密度的增加，不同位置的流速分布呈现出不同的趋势。上游调节长度不受植被斑块密度的影响，但是稳定尾迹的长度会受到很大影响。