  In low Mach number aeroacoustics, the well known disparity of scales makes it
possible to apply efficient hybrid simulation models using different meshes for
flow and acoustics, which leads to a powerful computational procedure. Our
study applies the hybrid workflow to the computationally efficient perturbed
convective wave equation with only one scalar unknown, the acoustic velocity
potential. The workflow of this aeroacoustic approach is based on three steps:
1. perform unsteady incompressible flow computations on a sub-domain; 2.
compute the acoustic sources; 3. simulate the acoustic field using a mesh
specifically suited for computational aeroacoustics. In general, hybrid
aeroacoustic methods seek for robust and conservative mesh-to-mesh
transformation of the aeroacoustic sources while high computational efficiency
is ensured. In this paper, we investigate the accuracy of a cell-centroid based
conservative interpolation scheme compared to the more accurate cut-volume cell
approach and their application to the computation of rotating systems, namely
an axial fan. The capability and robustness of the cut-volume cell
interpolation in a hybrid workflow on different meshes are investigated by a
grid convergence study. The results of the acoustic simulation are in good
agreement with measurements thus demonstrating the applicability of the
conservative cut-volume cell interpolation to rotating systems.
