Prediction of Sound Generated by Complex Flows at Low Mach Numbers

摘要

We present a computational aeroacoustics method to evaluate sound generated by low Mach number flows inncomplex configurations in which turbulence interacts with arbitrarily shaped solid objects. This hybrid approach isnbased on Lighthill’s acoustic analogy in conjunction with sound source information from an incompressiblencalculation. In this method, Lighthill’s equation is solved using a boundary element method that allows the effect ofnscattered sound from arbitrarily shaped solid objects to be incorporated. We present validation studies for soundngenerated by laminar and turbulent flows over a circular cylinder at Re u0001 100 and 10,000, respectively. Our hybridnapproach is validated against directly computed sound using a high-order compressible flow solver as well as thensolution of the Ffowcs Williams and Hawkings equation in conjunction with compressible sound sources. Wendemonstrate that the sound predicted by a second-order hybrid approach is as accurate as sound directly computednby a sixth-order compressible flowsolver in the frequency range inwhich low-order numerics can accurately resolventhe flow structures. As an example of an engineering problem, we calculated the sound generated by flow over annautomobile side-view mirror and compared it to experimental measurements.