Comparison of Mixture and VOF Models for Numerical Simulation of Air–entrainment in Skimming Flow over Stepped Spillways

Abstract

Because stepped spillways can significantly reduce the depth and size needed for a stilling basin at the toe of a dam and lead to great economic benefit, these spillways are increasingly attractive in hydraulic engineering. In this paper, for investigation of Mixture and VOF method's ability, Air-Entrainment in skimming flow over the stepped spillways is simulated by using fluent software. The numerical simulation results of free surface, velocity components and air concentration in water and circumstance of air entry into the water have been compared with the experimental results. It was found, downstream of the inception point of free-surface aeration where rapid free-surface aeration is observed, free surface is simulated better by Mixture method.