A particle accelerated CFD-BEM technique applied to aeroacoustic scattering

A particle accelerated computational fluid dynamics (CFD) - boundary element method (BEM) technique is proposed that allows the total sound pressure field produced by low Mach number flow past a rigid body to be predicted. An incompressible CFD solver is used to calculate the transient hydrodynamic flow field. The CFD/BEM coupling technique is then used to compute the acoustic pressure and pressure gradient incident on the body. The incident acoustic field is calculated based on a near-field solution of Lighthill's analogy. Numerical techniques are employed to accurately evaluate the strongly singular and hypersingular surface and volume integrals. A particle condensation technique is applied to accelerate the incident field computations and reduce the amount of data that must be stored during the CFD analysis. The incident field is then combined with a BEM model of the body to predict the scattered sound pressure field. The BEM model solves the Burton-Miller boundary integral equations to guarantee a unique solution at all frequencies. Results from the particle accelerated CFD-BEM technique are presented for flow past a circular cylinder with Reynolds number, ReD=100 and Mach number, M=0.02. The directivity of the sound pressure field at the vortex shedding frequency and its harmonics predicted using the condensation technique are compared with non-condensed results as well as results obtained using Curle's analogy.