Comparing of Flow Pattern and Energy Dissipation over Different Forms of Stepped Spillway

Abstract

Stepped spillways are one of the main energy dissipaters in hydraulic structures. In this paper, a numerical modeling of the flow over different forms of stepped spillway has been developed and the results were compared. The base model was calibrated with experimental data. The computational fluid dynamics model which solves the RANS equations coupled to a surface-capturing algorithm to predict the main features of flow water. This included the determination of water surface, the development of swirling flow, and resulting pressures over the steps. The model was developed using the volume of fluid (VOF) method. In this paper, flow velocity at the end of spillway, and energy dissipation rate were compared in different height of steps. The RNG model of turbulence with wall functions was used to compute the eddy viscosity. Also Structured hybrid grids were used to accommodate the geometry of the stepped spillway included upstream, steps and downstream. Agreement between numerical results and experimental data showed that RNG turbulent model and VOF method for predicting the water surface in the stepped spillway were suitable. This study indicates the capability of a numerical model using the VOF technique to predict the flow variables over the complex stepped spillway.