Investigating the effects of geometry on the flow characteristics and energy dissipation of stepped spillway using two-dimensional flow modelling

Critical issues governing the performance of hydraulic structures such as spillways and chutes include stability and safety of the structure itself. The stepped spillway aims to dissipate the energy of the flow, which will decrease the stilling basin volume and the risk of cavitation. It is important to have a good understanding of flow characteristics through these structures. In this study, a two-dimension flow model was developed to assess the effect of geometry on flow patterns (flow regimes) and energy dissipation, based on varying several geometry parameters over step spillway. The models tested included three stepped spillways (6 steps, 8 steps, and 10 steps). The slope angle was 26.6° and models were developed at 1:10 scale with a model height of 0.3 m. Geometry parameters tested included the height of the step (h s ), and the number of steps (N s ). The ANSYS-Fluent software, the volume of fluid (VOF) model, and the k-ϵ model were applied to all models. The k-e model was used to simulate turbulence. The base model (6 steps model) was calibrated with the data of the experimental work. The outcomes of downstream velocity and energy dissipation that were calculated by the developed 2D flow model were compared with the current and previous experimental works and showed a close correlation within a (±6%) tolerance.