Domain decomposition technique for aeroacoustic simulations Original Research Article

A computational tool for the simulation of time harmonic sound propagation in open domains is proposed. It consists of a two step technique. In the first step the viscous flow field is calculated, solving the incompressible Navier–Stokes equations. In the second step the acoustic field is obtained solving the Lighthillʹs wave equation. The two calculations are performed on two different grids, both formed by non-conforming subdomains. The Lighthillʹs wave equation is solved in the frequency domain, with a high order accurate compact finite difference scheme. To test the acoustic solver, the phenomenon of wave diffraction past an obstacle is calculated. The results confirm that the interface transmission conditions as well the non-reflecting boundary conditions do not affect the accuracy of the scheme. The complete aeroacoustic technique is applied to the simulation of the noise radiation from a cavity with a grazing subsonic laminar boundary layer. The flow field presents a periodic vortex shedding past the cavity, the vortical flow being a noise source. The numerical results show the existence of the directivity character of the acoustic radiation.