Numerical calculation of air entrainment rates due to intake vortices

In the present study, a numerical investigation was performed to estimate air entrainment rates due to intake vortices in different hydraulic conditions. The numerical model was verified with the experimental data. The agreement between numerical and experimental results for air entrainment rates and circulation was good. Regarding formed funnel shape flow pattern in the reservoir towards the horizontal intake, its boundaries at presence of vortices were analyzed. By considering the minimum air entrainment ratio as a new approach, critical submergence was also calculated numerically. Results showed that allowing minimum air entrainment ratio of β = 1 × 10⁻⁵ can cause critical submergence decreases at least about 12%. Moreover, turbulence analysis and discussion were performed in the presence of vortex at the intake. This numerical simulation may be helpful to make a deeper understanding in determining the amount of entrained air and turbulence analysis in the presence of vortex and the critical submergence at horizontal intakes.