In this hybrid simulation method, which is intended to simulate aeroacoustics of low Mach number flows, the incompressible flow model is used for the calculation of sound sources, while the differential wave equation is used to calculate the propagation of sound generated by these sources. The acoustics wave equation implemented in Ansys Fluent is derived from the acoustics perturbation equations by Ewert and Schroeder [168] under the assumption of constant density flow. The main advantages of this model are:

• Extended applicability compared to the Ffowcs Williams and Hawking integral solver, which can be used only to model the sound propagation in open space (see The Ffowcs Williams and Hawkings Model ).

• Simple and convenient workflow of hybrid aeroacoustics simulations, without any data exchange between different software components via disk files, and without the interpolation of sound sources on a different mesh. A transient co-simulation of fluid flow and noise propagation using the same domain and mesh has been chosen for the current implementation.

The method includes the Kirchhoff integral tool to propagate the wave equation solution to the remote receivers in open space.