TURBULENCE MODELLING OF STATISTICALLY PERIODIC FLOWS: THE CASE OF THE SYNTHETIC JET

摘要

Computations of a synthetic jet are performed with usual RANS-equations solved in a time-accurate mode (URANS), with the standard k-ε model and the Rotta+IP second moment closure. The purpose of the present work is to investigate the ability of these standard turbulence models to close the phase-averaged Navier-Stokes equations. Results are compared with recent experiments by Yao et al. provided to the CFD Validation of Synthetic Jets and Turbulent Separation Control workshop held in 2004. Comparisons of the performance of the models with experimental data show that the models are globally able to reproduce the dynamics of the flow. However, several characteristics are not well predicted, e.g., convection velocities and spreading rates. Moreover, results suggest that second moment closure is the minimum modelling level suitable for pulsed flows: regions of negative production play a significant role, and their prediction requires to solve transport equation for the Reynolds stresses.