Aeroacoustic wave equation based on Pierce’s operator applied to the sound generated by a mixing layer

For the first time, this paper presents the sound prediction capabilities of an aeroacoustic wave equation based on Pierce's operator (AWE-PO). The wave equation is applied to a two-dimensional mixing layer, providing a solution which is compared with the far-field acoustics of a direct numerical simulation. In contrast to a direct numerical simulation, the computed Lighthill's wave equation and the AWE-PO rely on a hybrid workflow to predict the generated sound. Special attention is put on the visualization and interpretation of the right-hand side of both equations. Finally, the results of the acoustic far-field pressure are compared. It is shown that the radiated sound field's directivity, propagation, and convection effects are captured well for both wave equations. The error of the acoustic intensity compared with the direct numerical simulation is less than 2 dB for Lighthill's equation and AWE-PO. This error is comparable with the errors reported for Lighthill's equation in previous studies. To conclude, the presented wave equation reasonably predicts mixing layer sound, and the acoustic far-field pressure results are in good agreement with the DNS.