Influence of Source Term Interpolation on Hybrid Computational Aeroacoustics in Finite Volumes

Due to differences in length- and energy scale, it is common in hybrid computational aeroacoustics (CAA) to use different meshes for the computational fluid dynamics (CFD) and the acoustic calculations. Therefore, an interpolation is needed to map field quantities from the CFD mesh to the acoustic mesh. The computational effort for the interpolation and the resulting accuracy vary for different methods. The relative cost of interpolation between the meshes compared to the total CAA simulation time is usually small but can be significant under various circumstances. This contribution discusses the source term interpolation for the case that the CFD as well as the acoustic computation are performed in finite volumes (FV). The CAA code is developed on the basis of the OpenFOAM(r) framework. The main focus of this work is on CAA methods which use time derivatives of the incompressible flow pressure as their acoustic source term. The authors compare different methods of interpolation which are especially well suited for FV simulation with these methods. A main focus is the influence of different interpolation strategies on the numerical behavior of the simulation. Computation times are compared and mesh influences are studied.