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Discharge Computation of Trapezoidal Broad-Crested Side Weir in Subcritical Flow Regime using Spatially Varied Flow Theory

Document Type : Original Article

Authors

1 M. Sc. Department of Irrigation and Reclamation Engineering, University of Tehran, Karaj, Iran

2 Associate Professor, Department of Irrigation and Reclamation Engineering, University of Tehran, Karaj, Iran.

Abstract

Flow over side weirs has been the subject of many studies. Most of these studies related to sharp crested side weirs with rectangular cross section and less attention has been given to the discharge coefficient over the broad-crested side weirs with trapezoidal cross section. In this research a comprehensive laboratory study including 187 tests has been conducted to investigate the discharge coefficient over the broad-crested trapezoidal side weir under subcritical flow regime. Since a complete analytical solution of the governing equation for a side weir is not possible due to nonlinearity and the many variables involved, in this research water surface profile along the side weir is computed by using the fourth order Runge–Kutta method. By analyzing experimental data and using dimensional analysis as well as statistical analysis, some relationships in order to estimate the discharge coefficient were proposed. It was founded that the discharge coefficient of flow depends on the Froude number, the ratio of initial depth to crest width and the side slope of the weir. The mean absolute percentage error of proposed relationship is about 4% and indicates that the numerical method is very accurate.

Keywords

References
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Irrigation and Drainage Structures Engineering Research
Volume 20, Issue 74 - Serial Number 74
March 2019
Pages 1-12
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History
  • Receive Date: 03 February 2017
  • Revise Date: 09 July 2018
  • Accept Date: 22 July 2018
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