Underwater Acoustic Modeling and Simulation

639 Pages·2018·13.83 MB·English

by  Paul C. Etter

Underwater Acoustic
Modeling and Simulation

Underwater Acoustic
Modeling and Simulation
Fifth Edition
Paul C. Etter
CRC Press
Taylor & Francis Group
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Boca Raton, FL 33487-2742
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Library of Congress Cataloging-in-Publication Data
Names: Etter, Paul C., author.
Title: Underwater acoustic modeling and simulation / Paul C. Etter.
Description: Fifth edition. | Boca Raton : CRC Press, Taylor & Francis Group,
2018. | Includes bibliographical references and indexes.
Identifiers: LCCN 2017049571| ISBN 9781138054929 (hardback : alk. paper) |
ISBN 9781315166346 (ebook)
Subjects: LCSH: Underwater acoustics–Mathematical models.
Classification: LCC QC242.2 .E88 2018 | DDC 534/.23015118–dc23
LC record available at https://lccn.loc.gov/2017049571
Visit the Taylor & Francis Web site at
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To my wife Alice
and to my two sons and their families:
Gregory, Sophia, Elaina, and Renae
and
Andrew, Michelle, and Kale

Contents
Preface......................................................................................................................xv
Preface to the Fourth Edition ..................................................................................xix
Preface to the Third Edition ...................................................................................xxi
Preface to the Second Edition ..............................................................................xxiii
Preface to the First Edition ....................................................................................xxv
Acknowledgments ................................................................................................xxvii
Author ...................................................................................................................xxix
Chapter 1 Introduction ..........................................................................................1
1.1 Background ................................................................................1
1.1.1 Setting ..........................................................................1
1.1.2 Framework ....................................................................2
1.2 Measurements and Prediction ...................................................4
1.3 Developments in Modeling ........................................................8
1.4 Advances in Simulation ...........................................................11
1.5 Operational Challenges ...........................................................12
1.5.1 Naval Operations ........................................................13
1.5.2 O ffshore Industries .....................................................15
1.5.3 Operational Oceanography ........................................16
1.6 Inverse Acoustic Sensing of the Oceans..................................17
1.7 Standard Definitions ................................................................19
1.8 Historical Growth Curves .......................................................21
Chapter 2 Acoustical Oceanography ..................................................................23
2.1 Background ..............................................................................23
2.2 Physical and Chemical Properties ...........................................23
2.2.1 Temperature Distribution ...........................................25
2.2.2 Salinity Distribution ...................................................25
2.2.3 Water Masses ..............................................................27
2.3 Sound Speed ............................................................................29
2.3.1 Calculation and Measurements ..................................29
2.3.2 Sound Speed Distribution ..........................................32
2.4 Boundaries ...............................................................................38
2.4.1 Sea Surface .................................................................38
2.4.2 Ice Cover.....................................................................41
2.4.3 Sea Floor ....................................................................42
2.5 Dynamic Features....................................................................46
2.5.1 Large-Scale Features ..................................................46
2.5.2 Mesoscale Features ....................................................47
2.5.2.1 Fronts and Eddies .......................................47
2.5.2.2 Internal Waves ............................................55
vii
viii Contents
2.5.3 Fine-Scale Features ....................................................57
2.5.3.1 Thermohaline Staircases ............................57
2.5.3.2 Langmuir Circulation .................................59
2.6 Biologics ..................................................................................60
Chapter 3 Propagation I: Observations and Physical Models .............................63
3.1 Background ..............................................................................63
3.2 Nature of Measurements .........................................................64
3.3 Basic Concepts ........................................................................65
3.4 Sea-Surface Boundary .............................................................71
3.4.1 Forward Scattering and Reflection Loss ....................71
3.4.2 Image Interference and Frequency Effects ................73
3.4.3 Turbidity and Bubbles ................................................75
3.4.3.1 Open Ocean ................................................75
3.4.3.2 Coastal Ocean .............................................75
3.4.4 Ice Interaction .............................................................77
3.4.5 Measurements .............................................................79
3.5 Sea-Floor Boundary ................................................................79
3.5.1 Forward Scattering and Reflection Loss ....................80
3.5.1.1 A coustic Interaction with the
Sea Floor .....................................................80
3.5.1.2 Boundary Conditions and
Modeling .....................................................81
3.5.1.3 Geoacoustic Models ....................................82
3.5.2 Interference and Frequency Effects ...........................86
3.5.3 Attenuation by Sediments ..........................................87
3.5.4 Measurements .............................................................88
3.6 Attenuation and Absorption in Sea Water ...............................88
3.7 Surface Ducts ..........................................................................91
3.7.1 Mixed-Layer Distribution...........................................91
3.7.2 General Propagation Features ....................................95
3.7.3 Low-Frequency Cutoff ...............................................99
3.8 Deep Sound Channel .............................................................100
3.9 Convergence Zones ...............................................................102
3.10 Reliable Acoustic Path ...........................................................103
3.11 S hallow-Water Ducts .............................................................103
3.12 Arctic Half-Channel ..............................................................104
3.13 C oherence ..............................................................................106
Chapter 4 Propagation II: Mathematical Models ..............................................109
4.1 Background ............................................................................109
4.2 Theoretical Basis for Propagation Modeling .........................110
4.2.1 Wave Equation ..........................................................110
4.2.2 Classification of Modeling Techniques ....................112
Contents ix
4.3 Ray-Theory Models ...............................................................113
4.3.1 Basic Theory ............................................................113
4.3.2 Caustics ....................................................................115
4.3.3 Gaussian Beam Tracing ...........................................116
4.3.4 Range Dependence ...................................................117
4.3.5 Arrival Structure ......................................................119
4.3.6 Beam Displacement ..................................................122
4.3.7 Waveguide Invariant .................................................123
4.3.8 Energy-Flux Models .................................................125
4.3.9 Advanced Algorithms ..............................................126
4.4 Normal-Mode Models ...........................................................128
4.4.1 Basic Theory ............................................................128
4.4.2 Normal-Mode Solution .............................................128
4.4.3 Dispersion Effects ....................................................131
4.4.4 Experimental Measurements ....................................131
4.4.5 Range Dependence ...................................................132
4.4.6 High-Frequency Adaptations ...................................135
4.4.7 Wedge Modes ...........................................................135
4.5 Multipath Expansion Models .................................................136
4.6 Fast-Field Models ..................................................................137
4.7 Parabolic Equation Models ...................................................139
4.7.1 Basic Theory ............................................................139
4.7.2 Numerical Techniques ..............................................142
4.7.3 Wide-Angle and 3D Adaptations .............................144
4.7.4 Range-Refraction Corrections ..................................146
4.7.5 High-Frequency Adaptations ...................................146
4.7.6 Time-Domain Applications ......................................147
4.8 Raymode Model—A Specific Example ................................147
4.9 Numerical Model Summaries ...............................................154
Chapter 5 Propagation II: Mathematical Models ..............................................177
5.1 Background ............................................................................177
5.2 Surface Duct Models .............................................................177
5.2.1 Ray-Theory Models ..................................................177
5.2.2 Wave-Theory Models ...............................................179
5.2.3 Oceanographic Mixed-Layer Models.......................181
5.3 Shallow-Water Duct Models ..................................................183
5.3.1 Shallow-Water Propagation Characteristics .............183
5.3.2 Optimum Frequency of Propagation ........................185
5.3.3 Numerical Models ....................................................187
5.3.3.1 Upslope Propagation .................................192
5.3.3.2 Downslope Propagation ............................193
5.3.4 Empirical Models .....................................................194
5.3.4.1 Rogers Model ............................................194
5.3.4.2 Marsh-Schulkin Model .............................196