Nomenclature

Hybrid CAA-approaches are commonly used for aero-acoustic engineering applications. For these kinds of numerical techniques, the computational domain is split into a noise generating region, where an aerodynamic field generates the aeroacoustic sources, and an acoustic propagation region. In this way, domain decomposition enables the use of differ-ent equations, computational grids and numerical techniques, thus improving the overall numerical efficiency. A crucial step for these hybrid methodologies is the determination of accurate coupling information from the unsteady aerodynamic simulation. In order to obtain more accurate results, an aerodynamic/acoustic splitting procedure is needed when compressible effects inside the source region are non-negligible or when acoustic results inside a turbulent flow region are required. For this purpose, a low-Mach number splitting is developed and validated for the application of both the aerodynamic noise generation by the flow over a square cylinder and the noise emitted by a rectangular cavity oscillating in a shear-layer mode regime. It is shown that the use of this splitting procedure largely improves the accuracy of hybrid CAA-simulation with only a minor additional cost