Computation of acoustic normal modes in the ocean using asymptotic expansion methods.

92 Pages·0.99 MB·en_US

by  Pimentel, Fernando M. M.;Chiu, Ching-Sang.

NAVAL POSTGRADUATE SCHOOL
Monterey, California
THESIS
Computation OfAcoustic
Normal Modes In The Ocean
Using Asymptotic Expansion Methods
by
Fernando M. M. Pimentel
September,1991
Thesis Advisor: Ching-SangChiu
Approved for public release; distribution is unlimited

Unclassified
security classification of this pace
REPORT DOCUMENTATION PAGE
la Report Security Classification Unclassified lb Restrictive Markings
2aSecurity Classification Authority 3 Distribution Availability of Report
2b Declassification Downgrading Schedule Approved for public release; distribution is unlimited.
4 Performing Organization Report Number(s) 5 Monitoring Organization Report Number(s)
6a Name of Performing Organization 6b Office Symbol 7a Name ofMonitoring Organization
Naval Postgraduate School (ifapplicable) 35 Naval Postgraduate School
6c Address (city, state, and ZIP code) 7b Address (city, state, and ZIP code)
Monterev. CA 93943-5000 Monterev. CA 93943-5000
8a Name ofFunding,Sponsoring Organization 8b Office Symbol 9 Procurement Instrument Identification Numfir
(ifapplicable)
8c Address (city, state, and ZIP code) 10 Source of Funding Numbers
Program Element No Project No Task No Work L'nit Accession No
n Tale (include security classification) COMPUTATION OF ACOUSTIC NORMAL MODES IN THE OCEAN USING
ASYMPTOTIC EXPANSION METHODS
12 Personal Author(s) Fernando M. M. Pimentel
13aType of Report 13b Time Covered 14 Date of Report (year, month, day) 15 Page Count
Master's Thesis From To September 1991 77
16 Supplementary Notation The views expressed in this thesis are those ofthe author and do not reflect the official policy or po-
sition ofthe Department of Defense or the U.S. Government.
17 Cosati Codes 18 Subject Terms (continue on reverse ifnecessary andidentify by block number)
Field Group subgroup Acoustic normal modes by asymptotic expansion
19 Abstract (continue on reverse ifnecessary andidentify by block number)
In this thesis, the use ofthe Wentzel-Kramers-BriHouin (YVKB) Theory to obtain the solution to the Helmholtz Equation
governing the acoustic normal modes is examined. Specifically, uniformly valid YVKB solutions for four classes of acoustic
WKB
normal modes in the ocean are derived and the accuracy of the approximation is tested against some exact solutions.
A
It is found that this inherently high frequency techniqueWhKasBan appreciable accuracy even at a frequency of 1 Hz. product
ofthis thesis is a computer program that solves for the modes for an arbitrary sound speed profile.
20 Distribution,Availability of Abstract 21 Abstract Security Classification
H D
unclassified unlimited same as report DTIC users Unclassified
22a Name of Responsible Individual 22b Telephone (includeArea code) 22c Office Symbol
Chin2-Sans Chiu [phone] OC/Ci
DD FORM 1473,84 MAR 83 APR edition may be used until exhausted security classification ofthus page
All other editions are obsolete
Unclassified
Approved for public release; distribution is unlimited.
Computation OfAcoustic Normal Modes In The Ocean
Using Asymptotic Expansion Methods
by
Fernando M. M. Pimentel
Lieutenant, Portuguese Navy
Submitted in partial fulfillment ofthe
requirements for the degree of
MASTER OF SCIENCE IN PHYSICAL OCEANOGRAPHY
from the
NAVAL POSTGRADUATE SCHOOL
September 1991