Noise radiated by a high-Reynolds-number 3-D airfoil

A large-eddy simulation (LES) of the flow around a NACA0012 airfoil at a chord-based Reynolds number of 5.0 × 106 and a Mach number of 0.22 is performed, and its results are compared with experimental data. The airfoil is placed without incidence to the turbulence-free incoming flow. The boundary layer in this configuration is expected to be initially laminar, and to transition to a turbulent state along the second half of the airfoil chord, and as such constitutes a challenging test-case for LES computations to repro-duce. The LES calculation is performed with a parallel code resolving the full compressible Navier-Stokes equations on structured curvilinear grids with optimized explicit high-order finite-difference schemes and filters. A preliminary two-dimensional simulation and a full three-dimensional simulation are performed for the same airfoil configuration. The two-dimensional simulation shows substantial discrepancies with available experimental data. On the other hand, flow results from the three-dimensional simulation compare favorably, and the LES is shown to capture boundary layer dynamics reasonably well. These results are a first step towards the development of the direct computation of noise emitted by a high-Reynolds-number airfoil. I