3D Computational Modeling of Flow over a Cup-shaped Spillway

Germichay dam is being constructed in 53 km northeast of the city of Mianeh, Eastern Azarbayejan,IRAN. The dam regulates the storage of water 46 million cubic meters a year. One cup-shaped spillway (an overfall spillway) and a horizontal canal with mild slope are adopted for flood release and share a common energy dissipating stilling basin. In this work the flow over the overfall spillway and in the canal is modeled with a 3D CFD-software. The CFD commercial model selected for this study solves Navier-Stocks equations with finite volume method (VOF). Selected turbulence model is RNG κ-ε model. In the absence of field data, experimental data for cup-shaped spillway collected in the laboratory were used to verify the simulated results. The aspects that are evaluated and investigated include the discharge capacity of the spillway and the water pressure on the structure. Numerical model was performed as the same geometry and flow data which used in experimental work. Satisfactory agreement was found between computed and measured discharge capacity of the spillway, flow pattern and the pressure acting on it in the laboratory. The comparison between numerical and experimental results showed that the 3D model with an error of about less than 10 % might become a useful tool for predicting the flow over the cup-shaped spillways before any decision for construction this type of complex structure in the nature.