Numerical simulation of air entrainment in uniform chute flow

Numerical models are used increasingly to tackle aerated flows for example in spillway design. However, these models are usually empirical and often lack thorough calibration. Herein a mixture model is calibrated with experimental data on uniform aerated flow from literature. A commercial code was used to solve the mixture Reynolds-averaged Navier-Stokes equations. Air entrainment was modelled with a turbulent kinetic energy based sub-grid model. The effects of drag, swarm correction and bubble diameter were evaluated with different models for sub-grid scale air-transport. Employing dynamic bubble size calculation and swarm correction resulted in similar to 10% typical error in the simulated mixture flow depth and concentration profile for chute slopes from 7.5 degrees to 75 degrees and unit discharges from 0.20 to 0.51 m(2 )s(-1). The obtained calibration parameters are independent of mean air concentration over a wide range of parameters; thereby providing a basis for air entrainment simulations of more complex flows.