Concurrent finite element simulation of incident and diffracted flow noise in computational aeroacoustics

Whether acoustic analogies or acoustic perturbation equations are used, the numerical simulation of flow-induced noise for low Mach numbers usually consists of a two-step approach. In the first step, an incompressible fluid dynamics simulation is carried out and its outputs are used as source terms for solving the acoustic field in the second step. In the presence of rigid boundaries, Curle's analogy is probably the most popular formulation. Alternatively, it has been shown that flow-induced noise by interaction with rigid bodies can also be posed as a diffraction problem. Taking advantage of this fact, in this work we propose a methodology based on coupling all involved partial differential equations to get the flow field, and, individually, its direct turbulent quadrupolar noise contribution and its diffracted boundary dipolar contribution, all at once, in a single time evolving finite element computational run. This straightforward approach could be very advantageous for a large variety problems such as those involving noise generated from duct terminations, or those related with the simulation of fricatives, in numerical voice production.