Noise Radiated by Flow Impingement on a Flat Plate Using DNS with a Virtual Boundary Method

Uniform flow impinging on the rectangular leading edge of a flat plate is simulated using an incompressible, two-dimensional direct numerical simulation with uniform grid, the solid surface being modelled by the virtual boundary method previously developed by Goldstein et al. Access is given to the hydrodynamic field at a Reynolds number of 500, which shows the separation at the edge, the development of a double recirculating bubble, a periodic vortex-shedding, and the generation of a boundary layer profile after the re-attachment point. Curle's analogy is then applied to evaluate the sound emission in the far field. Results are given in terms of far field pressure levels directivity and pressure spectra associated with surfacic or volumic sources. The emission from the surfacic sources reaches its maximum value in the direction perpendicular to the plate and acoustic frequencies tend to follow the main wall pressure frequencies of the flow, while the emission from the volumic sources exhibits a shear noise behaviour and acoustic frequencies seem to be the double of the main velocity frequencies.