Computational Investigation of Energy Dissipation Using Rigid Stepped Spillway

Spillways are the hydraulic structures used to destroy the surplus kinetic energy of floodwater downstream of the dam, having applications in flood mitigation, river engineering, and soil and water conservation. It is a concern over the past years that flood damages the dam structure due to overtopping, so it is important to reduce the impact of flooding over the structure by providing a safe passage of water. Steps provided over spillways improve the efficiency of energy dissipation from rapidly varied Cascades. In this research paper numerical simulation of flow over a rigid stepped spillway is performed using the CFD technique using the k-ε turbulence model with the Volume of Fluid (VOF) method to resolve the dynamics of free surface flow. Three models having three steps with fixed spillway heights of 30 cm and varied step dimensions (10 cm, 15 cm, 20 cm) of spillway were tested for flow characteristics. Five different discharges per unit width ranging from 0.020 to 0.95 m2 /sec were passed over each model. The conclusion from the result is that energy dissipation increases with an increase in step width and decreases with an increase in flow rate. The present study is in good agreement with the past studies.