Acoustic-gravity waves induced by vortices horizontally moving underwater.

In this article, the governing equation of acoustic gravity waves is derived. Based on the governing equation, acoustic-gravity waves induced by a cylinder horizontally moving under water are investigated. Strong anisotropy phenomena are observed from the frequency spectra of the acoustic-gravity waves. According to the results, a set of line spectra, which are approximately two sets of continuous spectra, can be observed in the spectrum of the acoustic-gravity wave. A semi-analytic solution for the acoustic-gravity wave generated by the moving vortex pair in two-dimensional space is obtained with Green’s function to analyze the characteristic frequencies of the spectrum. The far-field solution of acoustic-gravity waves in three-dimensional space is asymptotically analyzed to explain phenomena observed from the frequency spectra. [ABSTRACT FROM AUTHOR]