Numerical investigation of energy dissipation rate in stepped spillways with lateral slopes using experimental model development approach

The water flow in the dam spillway has a lot of energy. This energy can cause an increase in flow velocity, damaging the installations as well as erosion of the riverbed in downstream. The use of stepped spillways is one of the common methods to dissipate energy during the flow of spillway and reduce the dimensions of the stilling basin in the dams. One of the main parameters affecting the rate of energy loss in stepped spillways is the spillway geometry. In this study, the effect of using five different stairs with new and different geometries, in comparison with previous studies, was investigated in terms of energy dissipation. The simulation was performed by Flow 3D software and by the turbulence model (RNG) for discharges between 0.00213 and 0.0121 m3/s. The (RNG) and (k–ε) turbulence models were used for calibration, which (RNG) had better results. The simulation results were compared with the experimental model results where the RMSE error index for type A–E spillways, 0.035, 0.014, 0.021, 0.032, and 0.031, respectively. After this step, to improve the experimental model, barriers were placed on the type D spillway, which was the best experimental model for energy dissipation. Numerical simulation results show that adding these barriers increases the energy dissipation by 15%.