The effect of the end sill shape of steps for two-phase flow over the stepped spillways was investigated in this paper. A quantitative assessment approach has been applied. Experimental and numerical tests were used for stepped spillways with different step configurations. The computational fluid dynamics (CFD) method with 2D flow model, including the volume of fluid (VOF), and the k-ε models were applied to conduct a critical analysis in different flow conditions. The step heights were hs = 0.03 m and 0.05 m, the step numbers were Ns = 10 and 6, respectively. The step configurations were Step models, Sill models, and Curve models with angle θ = 26.6°. The developed two-dimension model (2D) investigated the flow patterns, velocity distribution, and pressure for several step configurations. For validation, the R, MAPE, and RMSE were tested. The results showed the negative pressure at the flat steps at Nappe flow, meanwhile, the negative pressure did not appear at the Curve model. The indices MAPE and RMSE were 4.32, 0.21 respectively with R =0.996. In the CFD results, velocity and the pressure distributions were compared with the experiments and showed a correlation within a (±6%) tolerance. The Curve models were the best in terms of the flow characteristics.
The regimes of flow have been simulated for different flow conditions along the stepped spillway.
The velocity distribution has been simulated at the first step, mid-step, and last step.
The pressure distribution has been simulated for nappe and skimming flow at the first step, mid-step, and last step.
The water surface profile with streamlines of the flow have been simulated along the stepped spillway.