Implementation of a computational model for random directional seas and underwater acoustics
Date
2009
Authors
Bayindir, Cihan
Journal Title
Journal ISSN
Volume Title
Publisher
University of Delaware
Abstract
Acoustic wave propagation in the ocean is an old and interesting problem.
In the literature the problem of interaction of acoustic waves with the ocean surface
has drawn the attention of many researchers. This interaction problem is a very
complicated problem due to many physical processes involved. Some of the important
factors on the ocean surface which affects underwater communications are presence of
waves, turbulence generated by wind input, wave breaking, white capping, bubbles
and density, salinity and temperature effects.
In this thesis, the effect of linear and nonlinear surface gravity waves on
high frequency acoustic propagation is discussed. Realistic models of linear and
nonlinear surface gravity waves, which solve the exact governing equations, are
created, and these models are coupled with an acoustic Gaussian beam tracing
program called Bellhop. Since Bellhop is not capable of accounting for out of plane
scattering of acoustic rays, coupling is done only for two spatial dimensions, one
horizontal and one vertical.
The wave model provides velocity components in the normal direction to
the surface. These velocity components are used in the Doppler frequency shift
calculations of acoustic rays generated by Bellhop.
Data from an acoustic experiment are taken as experimental results and
coupled wave-acoustic model has been run with the same conditions and same
geometric layout of experiments.
Comparisons between experimental results and coupled wave-acoustic
model results are presented and the limits of model validity are discussed.