Author(s): Saebeh Abbaspour; Seyed Abbas Hosseini
Linked Author(s):
Keywords: Side weir; 3D flow; Velocity distribution; Separation zone; Energy and momentum correction coefficients
Abstract: Side weirs are used for flow control in irrigation and combined sewer systems. Flow conditions at side weirs are complex and three-dimensional in nature. Diversion of flow at side weirs intensifies the non-uniformity of the velocity distribution in the main channel. This asymmetry causes the correction coefficients of the kinetic energy and momentum (α and β, respectively) to be greater than unity. In such condition, the values of α and β are needed for flow analysis using the one-dimensional energy or momentum equations respectively. In spite of many studies on side weir flow, few of them have considered the non-uniformity of the velocity distribution in vertical direction. In this paper, a numerical model has been used to study the variation of α and β for both rectangular and trapezoidal side weirs. First, the abilities and accuracy of the numerical model were verified with the available experimental data. Then, flow simulation for several different side weirs was carried out. The simulation results showed that the velocity distribution depends on the both geometric and hydraulic characteristics of the side weir flows. Based on the generated data, some new relations have been proposed for estimation of α and β coefficients under different conditions. Separation zones, which are formed in a region around downstream of side weir, have been also studied in this paper. Results of this study can help the analysis of the side weir flows especially when a one-dimensional model is used.
Year: 2013