SUMMARY
Stepped spillway is a good hydraulic structure for energy dissipation because of the large value of the surface roughness. The performance of the stepped spillway is enhanced with the presence of air that can prevent or reduce the cavitation damage. The flow over a stepped spillway can be divided into nappe flow regime, transition flow regime and skimming flow regime. This study aims to investigate the effects of the non uniform step heights on the air-water flow properties at stepped spillways. The numerical results of air concentration, air_water velocity and turbulence kinetic energy are presented in this research. Within this work flow over stepped chute is simulated by using fluent computational fluid dynamics (CFD). The volume of fluid (VOF) model is used as a tool to simulate air-water interaction on the free surface thereby the turbulence closure is derived in the k -e turbulence standard model. The found numerical results agree well with experimental results.