UACE2017 Proceedings: Acoustic scattering from a slender object by bottom-bounced beam in deep water

Session:
Acoustic modelling and Inversion methods
Paper:
Acoustic scattering from a slender object by bottom-bounced beam in deep water
Author(s):
Bo Lei, Yixin Yang, Yong Wang, Hongliang Tian
Abstract:
Bottom bounce propagation occurs when a sound ray strikes the bottom and is reflected back to the surface of the water, consequently involving an annulus. The work focuses on the scattering problem in this annulus by a beam that is deliberately transmitted downwards at relatively steep angles. A scattering model based on the virtual source concept, including evanescent waves, has been exploited. The scattering field from a slender spheroid located in the typical shadow zone has been computed and analyzed with bottom-bounced incidence. Interesting scattering phenomena were observed. The results showed that the deep-water propagation and bottom bounce paths for the scattering waves always existed under the bottom bounce scheme, and that the specular scattering strength increases and directions differ with respect to the depression angles. On the horizontal plane, the propagation direction of specular scattered waves was close to the backward direction with increasing depression angle, which could be explained by the geometrical scattering theory. At depression angle of directional source ranging from 40°–50°, the bottom bounced scattered waves have more significant contribution at range approaching half of convergence range.
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