Accession Number:

ADA626383

Title:

Coupled Mode Problems for Bottom Interacting Sound and Coupled Mode Problems for Bottom Interacting Sound: Student Support (Assert)

Descriptive Note:

Corporate Author:

WASHINGTON UNIV SEATTLE APPLIED PHYSICS LAB

Personal Author(s):

Report Date:

2001-09-30

Pagination or Media Count:

6.0

Abstract:

The long-term goal of this research is to improve our ability to model and predict VLF acoustic propagation in shallow water with particular emphasis on the range dependence of the medium and the geoacoustic properties of the bottom, and to quantify the various factors affecting the overall acoustic energy budget in shallow water propagation. Our scientific objectives are to incorporate the effects of sediment anisotropy, strong sediment attenuation, and the effects of both deterministic and stochastic medium properties into a local coupled mode propagation model, and to develop accurate theory and robust numerical algorithms for the shallow water propagation problem. We are using an approach based on coupled local modes to carry out a systematic study of the effects of scattering, normal dispersion, anisotropy and intrinsic attenuation on a propagating shallow water acoustic signal with strong bottom interaction. The coupled mode theory is developed from the first order equations of motion for the stress and displacement rather than from the second order equations for a velocity or displacement potential. The later approach introduces coupling coefficients depending on the second-order derivatives with respect to the range coordinate of the local mode functions. These second-order coupling coefficients are an artifact of the formulation, and not present in the coupled mode theory based on the first order equations of motion.

Subject Categories:

  • Physical and Dynamic Oceanography
  • Acoustics

Distribution Statement:

APPROVED FOR PUBLIC RELEASE