Numerical study of flow characteristics over a compound rectangular weir

Abstract

This numerical study presents discharge prediction on range of upstream head levels over a compound rectangular broad crested weir (CR-BCW). The computational domain was built in Ansys workbench, while 3D simulation and postprocessing were performed in CFD based tool Fluent using volume of fluid (VOF) method. Two turbulence models, the Re-Normalization Group (RNG) K-ε and the Shear Stress Transport (SST) K-ω, were considered to check their capability for flow prediction under different upstream head levels. The calculated numerical results initially compared with the published experimental data. The Root Mean Square Error (RMSE) and the Mean Absolute Percent Error (MAPE) were used to check the accuracy of the numerical results. The findings demonstrate that the SST K- ω model presents better agreement with experimental data, indicating its optimal performance for simulating flow characteristics and predicting discharge over the CR-BCW model. This study does not only validate the SST K- ω model's effectiveness, but also highlights the sensitivity of hydraulic parameters to the choice of turbulence model, thus contributing valuable insights for the design and analysis of hydraulic structures.