Comparison of Three k-e Turbulence Models for Predicting Ventilation Air Jets

Published data on unconfined plane-wall jets and plane-free jets were reviewed and used to assess the accuracy of numerical simulations, A plane-free jet was numerically simulated using the standard k-e model and four nonuniform grid patterns (70 x32,100 x52,120 x 60, and 120 x 74), The solution for a plane-free jet with adequate grid resolution was in good agreement with the published data, A plane-wall jet was numerically simulated using five different grids (70 x 32, 100 x 52, 120 x 60, 120 x 74, and 120 x 92) and three k-e turbulence models (the standard k-e model. Lam and Bremhorst low Reynolds number model, and Lam and Bremhorst low Reynolds number model with wall functions). The simulations predicted velocity decay and velocity profile well, but overpredicted the jet spread and entrainment ratio by 20 to 40%, indicating the need for a better turbulence model for wall jet predictions.