Propagation of acoustic waves caused by parallel vortex-cylinder interaction in a non-uniform flow is numerically investigated, using high-order compact scheme. Flow around a non-rotating rigid cylinder is taken as a prototype of real-world flows with strong gradients of mean pressure and velocity. The influence of non-linearity on the directivity and amplitude of wave propagation has been studied for non-zero circulation of Vatistas vortex model. As the vortex strength increases, the contribution to the sound generation made by non-linear terms becomes more important. Several crucial features of the acoustic field obtained by non-linear simulations are shown to be different from those obtained by linear simulations. While linear predictions have suggested a low noise zone around the centerline, the non-linear simulation results reveal that the acoustic pressure is far from zero on the centerline.
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