Investigation of Energy Dissipation on Various Configurations of Stepped Spillways Considering Several RANS Turbulence Models

Abstract

Nowadays, the construction of low gradient stepped spillway on embankment dam is attracting considerable attention. The first aim of this study is to evaluate several RANS turbulence models for the simulation of flow hydraulic on different configurations of law gradient stepped spillways including non-uniform stepped spillway, pooled stepped spillway, and alternate flat and pooled stepped spillway. In this context, the simulation of flow over a stepped spillway with a combination of flat and pooled steps was also done for the first time. Six types of RANS turbulence models compromising eddy viscosity, k − ɛ, RNG k − ɛ, k − ω, SST k − ω, and omega Reynolds stress model (ω − RSM) were employed in the simulations. The comparison of experimental data with simulation results indicated that ω − RSM model, followed by k − ω model, is superior to the aforementioned turbulence models. The second purpose of this research is to compare different configurations of stepped spillways in terms of energy dissipation. For each configuration of stepped spillway, the flow simulation was performed at several mild slopes and step heights in addition to different discharges. It was observed that the alternate flat and pooled stepped slipway has the highest rate of energy dissipation rate in all geometries, promising an outstanding dissipater. It was often supposed that pooled stepped spillway dissipate more energy than flat stepped spillway on account of the pooled steps. However, the results indicated that flat stepped spillway is more effective than pooled stepped spillway regarding energy dissipation if the spillway slope is larger than 14°.