CFD computation and POD analysis for transonic buffet on a supercritical airfoil

The transonic buffet flow on the OAT15A supercritical airfoil is simulated by the solution of the cell-centered finite-volume method (FVM) based RANS (Reynolds-averaged Navier-Stokes) equations with the S-A (Spalart-Allmaras) one-equation turbulence model, as well as the implicit time-stepping scheme and the Roe scheme. On the basis of successful simulation of transonic buffet phenomenon caused by the shock-boundary layer interaction, studying the evolution of flow separation and it reveals a hysteresis phenomenon that the phase of shock movement is slightly ahead of the phase of lift fluctuation. To view the physical nature of transonic buffet, apply POD (Proper Orthogonal Composition) method to extract POD modes with the transient results as snapshots. An POD analysis from the perspective of coherent structure has been implemented.