Prediction of wind noise radiated from passenger cars and its evaluation based on auralization

This paper describes the prediction of radiated wind noise from automobiles and its reduction. The Lighthill acoustic analogy was employed to estimate the wind noise at far field. In order to compute accurate pressure fluctuations, which play a role as the noise sources in the analogy, an overlapped grid system is used to calculate flow fields in detail with a finite-difference method. This approach was applied to predict the wind noise radiated from a door mirror and a front pillar. Measured data are compared with the computed results of pressure fluctuations on the side-window surface. The predicted pressure fluctuations agree well with the experimental results. Then, shapes of the front pillar and the door mirror were modified based on the computed results so as to reduce the wind noise. The effects of the modification were proved by additional experiments.