Trapezoidal Side Weir Research Articles

Predicting trapezoidal and rectangular side weirs discharge coefficient using machine learning methods

Side weirs are useful and common devices in flow measurement issues. These weirs have been extensively used in hydraulic and environmental engineering applications. The characteristic of flow over side weirs are completely different from that over a weir normal to the approach channel. An accurate flow modeling over a side weir mainly depends on the proper estimation of discharge coefficient. In this study, the potential of two different machine learning methods, namely support vector machines combined with genetic algorithm (SVM–GA) and gene expression programming (GEP) were evaluated for predicting trapezoidal and rectangular sharp-crested side weirs discharge coefficient. Correlation coefficient (R), mean normalize error (MNE), and Nash–Sutcliffe index (NS) statistics are used for the evaluation of the model’s performances. The results showed that the SVM–GA model with R = 0.97, NS = 0.94, and MNE = 13% for trapezoidal side weir and R = 0.97, NS = 0.91, and MNE = 18% for rectangular side weir, in test period gives more accurate results than GEP. The results verify that the SVM–GA model can process used data series by better generalization ability and higher prediction accuracy.

Discharge coefficient for trapezoidal side weir

The designed length of the rectangular side weirs sometimes becomes too long that makes it non-practical from the engineering point of view. In order to decrease the length of channel opening with the desired water height, this study focuses on applying trapezoidal geometry for side weirs. The discharge coefficient needs to be found experimentally for any kinds of trapezoidal side weirs. For this study experimental tests have been carried out for trapezoidal side weir in order to obtain the discharge coefficient. The main dimensionless variables for the tests include: Upstream end Froude number (F1), w/y1, L/B, L′/L, w/L′ and sin (α). Finally, the relationship for De-Marchi’s coefficient in subcritical flow for trapezoidal side weir is presented based on the non-dimensional parameters of weir and flow. Eventually, all the data points are within ±10% limit, which shows the accuracy of the results of this study.

Flow over trapezoidal side weir

In this paper, the hydraulic characteristics of a sharp crested trapezoidal side weir have been experimentally and theoretically investigated. It was found that the DeMarchi coefficient of discharge for a sharp crested trapezoidal side weir in subcritical flow is related to the main channel Froude number, the side slope of weir, ratio of weir height to upstream depth of flow and ratio of weir length to upstream depth of flow. Suitable equations for the discharge coefficient are also obtained.