Capturing transition features around a wing by reduced-order modeling based on compressible Navier–Stokes equations

The three-dimensional transition in the flow around a NACA0012 wing of constant spanwise section at Mach number 0.3, Reynolds number 800, and incidence 20° is investigated by direct numerical simulation and reduced-order modeling. The interaction between the von Kármán and the secondary instabilities is analyzed. Irregular events in the flow transition modulating the spanwise undulation are highlighted and quantified. These transition features, including “local intermittencies” in the secondary instability pattern, are efficiently captured by a reduced-order model derived by means of the Galerkin projection of the compressible flow Navier–Stokes equations onto a truncated proper orthogonal decomposition basis.