Herein, the free surface flow over a broad-crested weir under different hydraulic heads was investigated. A series of experiments were conducted in a 5-m-long-flume to measure the 3D velocity profile around a rectangular weir using Acoustic Doppler Velocimetry (ADV). The efforts were undertaken to simulate the hydrodynamic field over the weir using open-source toolbox OpenFOAM with five turbulence models including standard k-ε, RNG k-ε, realizable k-ε, k-ω SST and LRR. The numerical results were compared to the experimental data obtained from laboratory measurements. It demonstrated that the k-ω SST and LRR models had the best performance in cases dealing with vortices. Then, separation zone patterns at three locations: behind, over and in front of the weir under different head ratios were examined. It was found that changing the head ratio does not have a notable effect on the relative dimension of separation flow over the weir, whereas the separation zone located behind and in front of the weir grew linearly. After raising the head ratio, the downstream separation zone was split into two significant vortices rotating oppositely. Discharge coefficients are calculated for a wide range of head ratios. It was concluded that Cd equaled 0.85 for head ratios up to 0.3 and then grew to 1.0 by increasing the head ratio.

在这里，研究了不同水头下宽顶堰上的自由表面流动。在 5 米长的水槽中进行了一系列实验，以使用声学多普勒测速仪 (ADV) 测量矩形堰周围的 3D 速度剖面。努力使用开源工具箱 OpenFOAM 模拟堰上的流体动力场，其中包括标准 k-ε、RNG k-ε、可实现 k-ε、k-ω SST 和 LRR 五种湍流模型。将数值结果与从实验室测量获得的实验数据进行比较。它表明 k-ω SST 和 LRR 模型在处理涡流的情况下具有最佳性能。然后，检查了不同水头比下堰后面、上方和前面三个位置的分离区图案。发现改变水头比对堰上分离流的相对尺寸没有显着影响，而位于堰后面和前面的分离区呈线性增长。提高水头比后，下游分离区分裂成两个相对旋转的显着涡流。流量系数是针对各种水头比计算的。得出的结论是，对于高达 0.3 的水头比，Cd 等于 0.85，然后通过增加水头比增长到 1.0。流量系数是针对各种水头比计算的。得出的结论是，对于高达 0.3 的水头比，Cd 等于 0.85，然后通过增加水头比增长到 1.0。流量系数是针对各种水头比计算的。得出的结论是，对于高达 0.3 的水头比，Cd 等于 0.85，然后通过增加水头比增长到 1.0。