Theoretical, CFD Simulation and Experimental Study to Predict the Flowrate Across a Square Edge Broad Crested Weir Depending on the End Depth as a Control Section

  • Sadiq S. Muhsun
  • Sanaa A. Talab Al-Osmy
  • Shaymaa Abdul Muttaled Al-Hashimi
  • Zainab T. Al-Sharify
Conference paper
Part of the Lecture Notes in Civil Engineering book series (LNCE, volume 53)


A rectangular broad crested weir is the one mostly used in hydraulic structures for measuring flow rates in open channels and rivers. This study is focused on finding the suitable position of the depth above the weir as control section for estimating the flow rate while avoiding the troubles of approach velocity. It was predicted that the end edge of the weir, as a control section, relates to the critical depth (Yc) as a function of the end depth (Ye). To determine the relationship between these, experimental tests were achieved with ten different values of the longitudinal slope. Statistical regression analysis indicated the relationship between Yc and Ye as about 1.522. Consequently, a new flow rate formula was derived to estimate the flow over the weir and provided a good agreement with the experimental tests. A 3D ANSYS FLUENT Ver. V.16.1 CFD model was also applied to simulate the problem and verify the equation. The water volume fraction and the stream flow pattern were taken into the consideration. The model was able to simulate the problem with a good accuracy for all cases with a percentage error less than 10% when compared to experimental results. Thus indicating that CFD models could be relied upon for describing complex flows.


Broad weir CFD Critical depth ANSYS Flow rate 



The authors would like to thank Mustansiriyah University ( Baghdad-Iraq for its support in the present work and the Hydraulic Laboratory staff in the College of Engineering for their support and helps with the experiments.


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Copyright information

© Springer Nature Switzerland AG 2020

Authors and Affiliations

  • Sadiq S. Muhsun
    • 1
  • Sanaa A. Talab Al-Osmy
    • 1
  • Shaymaa Abdul Muttaled Al-Hashimi
    • 1
  • Zainab T. Al-Sharify
    • 2
    • 3
  1. 1.Department of Water ResourcesCollege of Engineering, University of MustansiriyaBaghdadIraq
  2. 2.Department of Environmental EngineeringCollege of Engineering, University of MustansiriyaBaghdadIraq
  3. 3.Department of Chemical EngineeringUniversity of BirminghamBirminghamUK

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