Broad-crested weir is structure designed to measure the flow rates and to control the flood water in open channel. In the present numerical study, the Reynolds-Averaged Navier–Stokes equations are coupled with k −ε turbulence standard model to simulate the water flow over broad-crested weir by using the software Ansys Fluent. Volume of fluid (VOF) model is used as a tool to track the free surface flow.  This research aims to find new formulas for calculate the discharge coefficient (Cd) and to describe flow structure in the vicinity of backward broad crested. The found numerical results agree well with experimental results. The relative error between the measured and computed value of discharge coefficients does not exceed 2%. A very satisfactory agreement observed between numerical and experimental water surface profiles for different flow rates.


Discharge coefficient, Broad-crested weir, Ansys Fluent, VOF Model, water surface profile, Standard k −ε Model.

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