Nonlinear PLS Method for Subcritical Flows Over Sharp-Crested Rectangular Side Weirs
2Department of Civil, Water and Environmental Engineering, Assistant Professor, Shahid Beheshti University, Iran
3Department of Emergency Management, Assistant Professor, Malek Ashtar University of Technology, Iran
4Department of Civil Engineering, Undergraduate Student, Shiraz University, Iran
Side weirs are widely used for level control and flow regulation in hydraulic engineering applications such as irrigation, land drainage, and sewer systems. These hydraulic structures allow a part of the flow to spill laterally when the surface of the flow in the main channel rises above the weir crest. In fact, they can be served for adjustment and divert of flow with minimum energy loss. Previous investigators have extensively studied the hydraulic performance of sharp-crested rectangular side weirs (Fig. 1) and introduced different linear and non-linear equations for estimation of their De Marchi coefficient of discharge in subcritical flow, including proposed Eq. (1) by Borghei et al. [1].
Where CM=De Marchi coefficient of discharge (-); Fr1=Froude number at the upstream end (-), p=weir height (m); h1=flow depth at the upstream end of the side weir (m); L=opening length of side weir (m); and B=channel width (m).
In this study, based on over 170 experimental data available from previous investigators and through using the multivariable nonlinear partial least square (PLS) method, a new accurate nonlinear equation is presented for discharge coefficient CM of sharp-crested rectangular side weirs. The obtained empirical equation relating CM with the relevant geometric and hydraulic dimensionless parameters, in a rectangular open channel. Comparison between results of the new presented equation and the measured data shows that the new presented empirical equation can predict the discharge of diverted flow over side weirs with higher accuracy.
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