Large- and small-scale acoustic vortices intensities assessment

Abstract

A comparative assessment of large-scale vorticity intensities and local vortices in the acoustic interferential field at shallow sea was made. The assessment is based on the experimental field data. The source of a noise-like signal is a vessel moving in the direction of a combined receiver. The depth of the spot is 30 m. The receiving combined system was at a depth of 15 m. Acoustic field ray (mode) structure, the curl of which, as the experiment shows, is nonzero in the farfield of the acoustic source, possesses a large-scale vorticity. Local vortices are formed in the region of singularity points - dislocations and saddles. Studies have shown that local vortices appear sporadically against the background of large-scale vorticity, and their intensity level may exceed the level of large-scale vorticity by 10 - 20 dB. In the region of local vortex, the large-scale vortex interferential acoustic field phase structure "is broken". The large-scale vorticity intensity is about 10-1 - 10-2 of the signal acoustic field intensity. These results extend the modern concepts of interferential complex acoustic fields at shallow sea.