Computational Aeroacoustics (CAA)

An acoustic domain is simulated using a hybrid approach. Firstly, a steady or unsteady CFD simulation is carried out to determine the flow field of the acoustic domain. The CFD solution contains both the convective transport information and the turbulence information, from which the acoustic sources are then modeled. The input for the CAA simulation of the acoustic field is provided by the CFD  flow  field solution. The pure sound transport can then be calculated with a different system of equations, e.g. the linearized Euler equations (LEE) or the acoustic perturbation equations (APE).

The main difference between CAA and CFD are the different length scales. The hydrodynamic perturbations, calculated with CFD methods, move at the same velocity as the flow. In contrast, the acoustic perturbations move at the same velocity as the sound.