Numerical investigation of the energy dissipation process in stepped spillways using finite volume method

The purpose of this paper is to investigate the energy dissipation in stepped spillways using numerical method with ANSYS CFX software. In this study, finite volume method based on element was applied for modeling and the SIMPLE iterative algorithm was applied to couple the velocity and pressure terms. Field of flow solution was continued until reaching to remaining with amount of 10-5. The RNG k-ε model was used to evaluate the turbulence using CFX software to model the mixing of two-phase water-air and free-surface flow called Free Surface. This research has been continuously analyzed. To perform the validation and capability of software, at first a broad-crested weir mode were modeled and the results of model were compared with the laboratory model. Then the laboratory model of stepped spillway was selected and analyzed for various discharge. Consider to results of the energy dissipation in stepped spillway and broad-crested weir and comparing with experimental results, it can be concluded that numerical method as well as laboratory method has the ability to provide acceptable results in field analysis of flow in different types of stepped spillways and their results can be used to predict flow behavior for different conditions. The results of the presented numerical model showed the appropriate efficiency of stepped overflows in energy dissipation. For the model with the ogee crest, the dissipation rate for the selected flow discharge obtained from 80 to 90% and for the model with the broad cast weir, the energy dissipation obtained from 55 to 80%.