Practical Computational Aeroacoustics for Complex Confined Scattering Geometries in Low Mach Number Flows

The purpose of this paper is to demonstrate that a recently published methodology for predicting flow generated noise by compact surfaces under free-field conditions [1] can be extended to a different and more complex configuration of industrial interest. In the previous paper, the methodology was applied to low Mach number flow past a circular cylinder in free-field, where the Green's function and its derivative were obtained analytically. In this paper, the method will be applied to the case of low Mach number flow past a complex confined scattering geometry where both compact and non-compact surfaces are involved. Here the generation of noise is dominated by the interaction of the flow with a surface whose maximum dimension is shorter than the wavelength of interest. The analysis is based on the surface-source term of the Ffowcs Williams-Hawkings equation. The acoustic source data of the flow are generated by use of a Computational Fluid Dynamics (CFD) simulation. Due to the complexity of the scattering surfaces, the derivative of the Green's function must be obtained numerically through a Computational Acoustics (CA) simulation. The results have been validated through comparison with sound power measurements.