Comparison of aeroacoustic formulations for coupling of confined flows with the flow-guiding structure

The absence of combustion noise in electric vehicles results in a dominance of other sound sources, such as flow-induced sound in flow guiding components. The use of Computational Aeroacoustics (CAA) during the design phase is a promising way to fulfill packaging requirements and the ambitious demand for passenger comfort. By coupling the computational fluid domain with the surrounding structural domain through appropriate interface conditions, not only the sound generation and propagation within the fluid can be computed, but also the vibroacoustic sound emission of the flow-guiding structure can be simulated. For doing so, the (two-step) hybrid aeroacoustic approach is often used to deal with the disparity of scales between flow structures and audible acoustic wavelengths in CAA. When applying this two-step approach, several aeroacoustic formulations are available to compute the flow-induced sound. We compare different aeroacoustic equations, such as Lighthill’s wave equation and the Perturbed Convective Wave Equation (PCWE), regarding their suitability for coupling the aeroacoustic and structural mechanics domains. The comparison considers typical flow configurations of turbulent low Mach number airflows (Ma<0.3), assuming different flow speeds. The accuracy, the computational effort, and the applied computational procedure are analyzed.