Stepped Spillway Performance: Study of the Pressure and Turbulent Kinetic Energy versus Discharge and Slope

In the present study, flow over flat and pooled stepped spillways was simulated three dimensionally. The VOF method and k- ε (RNG) turbulent model was used to simulate the flow over the stepped spillway. The results indicated that the numerical model was acceptably capable of simulating the flow over the pooled and flat stepped spillways for different discharges. Following that, the effect of different discharges and slopes on the flow pattern over both stepped spillways was examined. Comparison of the results indicated that the pooled stepped spillway performed better in 10, 15, and 20-degree slopes for different discharges in comparison with the flat stepped spillway regarding decreasing the residual head at the end of the spillway. The results of turbulent kinetic energy showed that the maximum turbulent kinetic energy was greater in the pooled stepped spillway in comparison with the flat stepped spillway. Negative pressure was not formed near the steps’ bed in the pooled and flat stepped spillways. However, adjacent to the vertical face, negative pressure was formed in a larger area in the flat spillway in comparison with the pooled spillway, which increases the probability of cavitation phenomenon in the flat spillway.