The transport of pollutants in the large rivers especially in the lowest downstream reach of a river, in which the velocity and the intensity of flow turbulent become very low, is performed to a great extent by dispersion. Any measure to enhance the level of turbulence in the flow field will increase the mixing of pollutants. The main goal of the present study is to investigate how the transverse mixing is increased by using a triangular vane (TV). TV is a hydraulic structure used for bank protection and habitat restoration and is suitable for fish and other aquatic organisms. Experiments were carried out in a flume of 10m long and 0.8m wide. Two different conditions of with and no vane were tested under four different flow conditions. A salt solution was used as a tracer. An electronic concentration measuring equipment consisted of conductivity probes was used which can measure the concentration at 49 nodes in four cross-sections downstream simultaneously. The three-dimensional velocity components were also measured by using the electromagnetic velocity meter and the characteristics of three-dimensional flow patterns including turbulent kinetic energy (TKE) and the vertical distribution of the transverse velocity were analyzed. The result showed that the TV by deviating the velocity vectors to the transverse direction, by developing the secondary flows and by displacing the position of the rotating cells in different transverse sections, causes the transverse mixing to increase 3.2 times and to reduce the complete mixing length by as much as 76% compare to the case of no vane. The average values of the TKE found to be increased by as much as 3 times. Finally, a new dimensionless parameter has been proposed to correlate dimensionless transverse mixing to the flow parameters.

污染物在大江大河，特别是下游下游，湍流速度和强度都非常低的河流中，污染物的输送在很大程度上是通过弥散来实现的。任何提高流场湍流水平的措施都会增加污染物的混合。本研究的主要目标是研究如何通过使用三角叶片 (TV) 来增加横向混合。TV 是一种用于堤岸保护和栖息地恢复的水工结构，适用于鱼类和其他水生生物。实验在长10m、宽0.8m的水槽中进行。在四种不同的流动条件下测试了带和不带叶片的两种不同条件。盐溶液用作示踪剂。使用由电导探头组成的电子浓度测量设备，可同时测量下游四个横截面的49个节点的浓度。还利用电磁速度计测量了三维速度分量，分析了三维流型的湍动能（TKE）和横向速度的垂直分布特征。结果表明，TV通过将速度矢量向横向偏移，通过发展二次流以及在不同横截面中移动旋转单元的位置，使横向混合增加3.2倍，并减少完整混合长度与没有叶片的情况相比，高达 76%。发现 TKE 的平均值增加了多达 3 倍。最后，提出了一种新的无量纲参数，以将无量纲横向混合与流动参数相关联。