Accession Number : ADA313828

Title :   Final Technical Report for Grant N00014-94-1-0201 (Catholic University of America).

Descriptive Note : Final technical rept. 1 Jan 94-31 Aug 96,

Corporate Author : CATHOLIC UNIV OF AMERICA WASHINGTON DC DEPT OF ELECTRICAL ENGINEERING

Personal Author(s) : Beran, M. J.

PDF Url : ADA313828

Report Date : 31 AUG 1996

Pagination or Media Count : 9

Abstract : During this contract, research was performed to understand how acoustic radiation propagates in shallow channels using a full three-dimensional formulation that takes into account the finiteness of the characteristic correlation lengths of the index-of refraction fluctuations and surface height variations. The equations governing the modal coherence functions were derived by first developing difference equations over propagation distances that were large compared to the characteristic correlation lengths but small compared to the characteristic length during which there was significant energy transfer between modes. It was then shown under what conditions these equations could be reduced to partial differential equations that were valid for long-range propagation. Using a spectral formulation the equations were subsequently generalized to wide-angle scattering in the transverse direction. Differences between the two-dimensional and three-dimensional problems were found in a variety of cases. Numerical solutions were given to show how the energy is transferred between modes as the acoustic radiation propagates in the shallow channel.

Descriptors :   *SHALLOW WATER, *ACOUSTIC SCATTERING, *UNDERWATER ACOUSTICS, MATHEMATICAL MODELS, REFRACTIVE INDEX, ENERGY TRANSFER, BACKSCATTERING, WAVE PROPAGATION, PARTIAL DIFFERENTIAL EQUATIONS, ACOUSTIC SIGNALS, ACOUSTIC VELOCITY, ACOUSTIC DATA, CHANNELS(WATERWAYS), ACOUSTIC IMPEDANCE.

Subject Categories : Acoustics

Distribution Statement : APPROVED FOR PUBLIC RELEASE