Vortex features of acoustic intensity vector in the shallow water

pp. 209-216, vol. 14, 2011

Vladimir Shchurov
V.I. Ilichev Pacific Oceanological Institute, Vladivostok, Russia

Vladimir Kuleshov
V.I. Ilichev Pacific Oceanological Institute, Vladivostok, Russia

Alexis Cherkasov
Adm. G.I. Nevelskoy Marine State University, Vladivostok, Russia

Key words: sonogram; spectral density of acoustic pressure; histogram; Japanese Sea

Abstract: The vortex structure of acoustic intensity vector in the shallow water depending on a distance and frequency emitting was researched basing on the natural in-situ experiment. The experiment was fulfilled using the combined acoustic receivers in the Peter the Great Bay in the Japanese Sea. When axes x and y of rectangular system of coordinates being located in horizontal plane of the combined receiver, axis z was directed from surface to bottom. The receiver was submerged to ~70 m depth at the site depth of ~120 m; sound velocity on the surface was higher than that of the bottom’s one. To determine the vorticity there were calculated three components of rotor of intensity vector then, their histograms of distribution of probability density were plotted. In the work there were presented distribution histograms of the vorticity probability density of intensity vector for 110 Hz frequency under the different distances between source and receiver within ~1000–5000 m. In the case of single source the highest density of probability corresponds to magnitude of ± 1 for x- and y- norm components of rotor and 0 – magnitude for its z-component. As follows from the experiment the steady vorticity of acoustic intensity vector was observed along the entire distance (~4000 m) from source to receiver. The described mechanism of acoustic intensity transfer opens new possibilities in the research of acoustic features in the shallow water. The fixed vortex structures pose an interest as for physical acoustics, as for applied challenges of undersea acoustics.

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