Coupling acoustic perturbation equations and pierce wave equation for computational aeroacoustics

We present a currently developed approach for computational aeroacoustics (CAA). Thereby, we model the acoustic field in the region of the main acoustic sources by acoustic perturbation equations (unknowns are the acoustic pressure and particle velocity) and in all other regions by the convective acoustic wave equation according to Pierce (unknown is the acoustic scalar potential). This approach allows us to correctly obtain the acoustic pressure in regions of flow by fully taking into account refraction and convection effects. The acoustic perturbation equations as well as Pierce equation are solved by the Finite Element (FE) method. To guarantee the physical interface conditions for acoustic waves, we couple the equations along the common interface by a Mortar-FE ansatz. Numerical computations for the NACA 0012 aerofoil demonstrate both the reduction of computational time and the practical applicability of the developed CAA scheme.