Accession Number : AD0716744

Title :   The Propagation of Sound in a Wedge Shaped Shallow Water Duct,

Corporate Author : NAVAL ORDNANCE LAB WHITE OAK MD

Personal Author(s) : Bradley,David L. ; Hudimac,A. A.

Report Date : 12 NOV 1970

Pagination or Media Count : 96

Abstract : The acoustic field in a wedge shaped shallow water duct is described. Beginning with the inhomogeneous Helmholtz equation, integral transform techniques are used to obtain the field of a point source (the Green's function) for an extended Riemann surface. Image theory is applied to obtain the generalized geometric acoustic solution in a bounded medium, which is a sum of these point sources. The behavior in a wedge shaped duct and in a duct with parallel boundaries is compared. The geometric acoustic solutions are then transformed to normal mode of wave acoustic solutions. Calculation of the normal mode field of the wedge requires evaluation of an integral appearing in the solution by the method of steepest descents or saddle point integration. Further comparison is then made between the normal mode acoustic fields of the parallel duct and of the wedge shaped duct. Comparison of the theory with experimental data obtained in the Gulf of Mexico shows fair agreement. (Author)

Descriptors :   (*UNDERWATER SOUND, SHALLOW WATER), SOUND TRANSMISSION, WEDGES, INTEGRAL TRANSFORMS, STEEPEST DESCENT METHOD, COMPLEX VARIABLES, NUMERICAL INTEGRATION

Subject Categories : Physical and Dynamic Oceanography
      Acoustics

Distribution Statement : APPROVED FOR PUBLIC RELEASE