Direct Computation of Turbulent Boundary Layer Noise

Abstract

Aerodynamic noise from a turbulent boundary layer, also known as flow noise is a fundamental topic in flow-induced noise insofar as it determines the structural response of a surface submitted to this turbulent buffeting. For example, in the automotive applications, sound waves transmitted inside the interior of the vehicle come from two contributions: the direct transfer of the acoustic radiation, and the indirect transfer by the incompressible pressure loading which can excite the vibrational modes of the structure. The first one has a low efficiency but a transfer function close to one, whereas the second is more energetic but the transfer function becomes very weak at high wavenumbers. For the flow around a A-pillar, Alam et al. have shown that the mechanism associated with structural responses to turbulent wall flow is preponderant, but no study has quantified precisely the contributions of the direct and indirect transfers, and the question whether the acoustic part should be considered remains an open question.