An accurate RANS-based transition prediction approach (part I)

We present a numerical procedure to improve the performance of the classical Reynolds-Averaged Navier-Stokes approach for transitional flows by introducing a transition prediction tool in the RANS code. A black-box procedure able to estimate first the boundary layer quantities (starting from the pressure distribution) and then to compute the linear evolution of the fluctuations has been included in an existing RANS code. Thanks to the coupling to the eN method, the transition location is predicted and periodically imposed during the RANS computations. The approach proposed in this paper to predict the transition location and the laminar flow extension is based on a numerical framework based on the coupling between a high-fidelity, Reynolds–Averaged Navier–Stokes (RANS) tool and Linear Stability Equations. According to this method, boundary layer equations are written in conical formulation and the solution of RANS equations and transition onset is obtained through an eN method based on the PSE calculations. The validation of the present approach has been achieved by comparing the numerical results against the experimental data documented in the ETRIOLLA project