Computation of the noise generated by low Mach number flows around a cylinder and a wall-mounted half-cylinder

For modern cars, aerodynamic noise is becoming the major source of annoyance during peri-urban trips. To take this point into consideration from the vehicle development and to improve the interior comfort, appropriate numerical methods have to be developed. The estimation of the broadband noise generated by low Mach number flows about M 0.1, considered in this study, are obtained by applying a two-step method combining incompressible CFD calculations with acoustic analogy. In this paper, the advanced-time algorithm is developed to allow the estimation of all the terms of Ffowcs Williams and Hawkings’ equation and particularly the volume terms. The noise corresponding to a cylinder flow is then used to validate this approach and to compute the broadband noise radiated by a 3-D incompressible and turbulent flow. The algorithm is then applied to a wall-mounted half-cylinder corresponding to a simplified side-mirror shape. In order to validate the half-cylinder aeroacoustic calculations, the numerical results are favourably compared to measurements recently carried out.

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