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The transport industries face a continuing demand from customers and regulators to improve the acoustic performance of their products: reduce noise heard by passengers and passersby; avoid exciting structural modes. In both the aerospace and automotive areas, flow-induced noise makes a significant contribution, leading to the desire to understand and optimize it through the use of simulation. Historically, the need for time-consuming, computationally expensive transient simulations has limited the application of CFD in the field of acoustics. In this paper are described efficient simulation processes that, in some instances, remove the requirement for transient analyses, or significantly reduce the total process time through intelligent pre-processing. We will outline this process and provide both automotive and aerospace industrial examples, including analyses of highly complex geometries found in real life.

The interior noise in a vehicle that is due to flow over the exterior of the vehicle is often referred to as ‘windnoise’. In order to predict interior windnoise it is necessary to characterize the fluctuating surface pressures on the exterior of the vehicle along with vibro-acoustic transmission to the vehicle interior. For example, for greenhouse sources, flow over the A-pillar and side-view mirror typically induces both turbulence and local aeroacoustic sources which then excite the glass, and window seals. These components then transmit noise and vibration to the vehicle interior. Previous studies by the authors have demonstrated validated CFD (Computational Fluid Dynamics) techniques which give insight into the flow-noise source mechanisms. The studies also made use of post-processing based on temporal and spatial Fourier analysis in order to quantify the amount of energy in the flow at convective and acoustic wavenumbers.