Numerical Study on the Mechanism of Wind Noise Generation About a Car-Like Body

Abstract

Three-dimensional flow separation about the sharp-edged front-pillar of a car-like body at high cruising speed is numerically studied. A time-dependent and full Navier-Stokes simulation is carried out for the understanding of mechanism of wind noise generation due to the vortical flow motions. The surface pressure fluctuations on the front-side window are examined in terms of wind noise, based on a simplified Lighthill-Curle’s equation. The simulated results are validated regarding the numerical grid resolution and assessed by comparison with the conventional acoustic theory. The analyses of the simulated flow-field data indicate that there is a strong relationship between the vortical motions associated with the flow separation and the surface pressure fluctuations on the front-side window. The bifurcations of flow geometry, such as the breakdown of a separated vortex as well as the vortex-vortex interaction, seem to be most strongly related to the production of surface pressure fluctuations.