Numerical Modeling of Flow Over a Rectangular Broad-Crested Weir with a Sloped Upstream Face

The objective of this study was to evaluate the effect of the upstream angle on flow over a trapezoidal broad-crested weir based on numerical simulations using the open-source toolbox OpenFOAM. Eight trapezoidal broad-crested weir configurations with different upstream face angles (theta = 10 degrees, 15 degrees, 22.5 degrees, 30 degrees, 45 degrees, 60 degrees, 75 degrees, 90 degrees) were investigated under free-flow conditions. The volume-of-fluid (VOF) method and two turbulence models (the standard k-epsilon model and the SST k-w model) were employed in the numerical simulations. The numerical results were compared with the experimental results obtained from published papers. The root mean square error (RMSE) and the mean absolute percent error (MAPE) were used to evaluate the accuracy of the numerical results. The statistical results show that RMSE and MAPE values of the standard k-epsilon model are 0.35-0.67% and 0.50-1.48%, respectively; the RMSE and MAPE values of the SST k-w model are 0.25-0.66% and 0.55-1.41%, respectively. Additionally, the effects of the upstream face angle on the flow features, including the discharge coefficient and the flow separation zone, were also discussed in the present study.