Vortex particle methods in aeroacoustic calculations

The connection between vortex particle methods and aeroacoustics is considered within the framework of Lighthill’s acoustic analogy which allows to decouple the flow from noise propagation. For the flow, techniques such as tree-algorithms and the particle-mesh method are brought together with the aim to achieve the best possible performance in view of analyzing complex problems. The flow results are then input to the acoustic wave equation which is solved in integral form. It will involve monopole, dipole and quadrupole terms which can be successively integrated. The significance of such an approach is first demonstrated in two problems, both related to vortex–solid interactions. The first is a generic one and considers the interaction of a vortex filament interacting with a sphere while the second considers helicopter noise as an example of a complex engineering set-up.