Solution Comparison: Category 5, Problem 1

Aeolian tones from flow over cylinders are known to be significant with airframe and power plant noise (tubular heat exchanger, power transmission lines and chimneys). The purpose of this benchmark problem is to test the ability of a CFD/CAA code to accurately and effectively predict sound generation by viscous flows over a blunt body and sound propagation through interactions with solid wall and moving flows.

Unfortunately, no exact solution is available for this category; thus, numerical solutions from each contributor are carefully compared with. The comparison of calculated strouhal numbers of vortex shedding with experimental data is presented. There is small discrepancy between the calculated data. It is also observed (not shown here) that the calculated fluctuating forces exerted on the cylinders show some differences between the contributors. These differences also make the variant directivities of acoustic pressure, which is shown. Therefore, only for the comparison of acoustic computation, the directivities are normalized by St . C2L,RMS to which the mean square value of the acoustic pressure is theoretically known to be proportional in far field. The normalized directivities are shown.