Estimation of automotive wind noise by coupling direct noise computation to statistical energy analysis

A statistical energy analysis approach was developed in this paper for the prediction of the sound transmitted through a flexible plate loaded by the turbulent wake of a car rear view mirror. The fluid loading is simulated using a direct noise computation code. This code solves the full compressible three dimensional Navier-Stokes equations with highly accurate space and time algorithms and is able to capture the low amplitude acoustic part of the wall pressure fluctuations. The computed wall pressure field is used as power input in a statistical energy analysis model coupling the flexible plate to an acoustic cavity. Although the acoustic component is of small magnitude compared to the convected component of the fluid loading, it is shown that the non-resonating plate modes provide an efficient transmission path to the acoustic excitation which cannot be neglected below the coincidence frequency of the plate. Above this critical frequency, the sound pressure inside the cavity is driven by the resonant modes and the acoustic component of the wall pressure fluctuation.