Practical Ship Hydrodynamics

280 Pages·2000·2.2 MB·English

by  Volker Bertram

Practical Ship Hydrodynamics
Practical Ship Hydrodynamics
Volker Bertram
Butterworth-Heinemann
LinacreHouse,JordanHill,OxfordOX28DP
225WildwoodAvenue,Woburn,MA01801-2041
AdivisionofReedEducationalandProfessionalPublishingLtd
Firstpublished2000
VolkerBertram2000
Allrightsreserved.Nopartofthispublication
maybereproducedinanymaterialform(including
photocopyingorstoringinanymediumbyelectronic
meansandwhetherornottransientlyorincidentally
tosomeotheruseofthispublication)withoutthe
writtenpermissionofthecopyrightholderexcept
inaccordancewiththeprovisionsoftheCopyright,
DesignsandPatentsAct1988orunderthetermsofa
licenceissuedbytheCopyrightLicensingAgencyLtd,
90TottenhamCourtRoad,London,EnglandW1P9HE.
Applicationsforthecopyrightholder’swrittenpermission
toreproduceanypartofthispublicationshouldbe
addressedtothepublishers
BritishLibraryCataloguinginPublicationData
Bertram,Volker
Practicalshiphydrodynamics
1. Ships–Hydrodynamics
I. Title
623.8012
LibraryofCongressCataloguinginPublicationData
Bertram,Volker.
Practicalshiphydrodynamics/VolkerBertram.
p.cm.
Includesbibliographicalreferencesandindex.
ISBN0750648511
1. Ships–Hydrodynamics I. Title.
VM156.B4572000
623.8012–dc21 00-034269
ISBN0750648511
TypesetbyLaserWords,Madras,India
PrintedinGreatBritainby
Preface ............................................. ix
1 Introduction .................................. 1
1.1 Overview of problems and
approaches ............................................ 1
1.2 Model tests (cid:133) similarity laws .............. 4
1.3 Full-scale trials ................................. 8
1.4 Numerical approaches
(computational fluid dynamics)............... 9
1.4.1 Basic equations............................. 9
1.4.2 Basic CFD techniques................... 14
1.4.3 Applications................................... 15
1.4.4 Cost and value aspects of CFD.... 19
1.5 Viscous flow computations............... 22
1.5.1 Turbulence models........................ 23
1.5.2 Boundary conditions...................... 26
1.5.3 Free-surface treatment.................. 28
1.5.4 Further details............................... 29
1.5.5 Multigrid methods.......................... 31
1.5.6 Numerical approximations............. 32
1.5.7 Grid generation ............................. 34
2 Propellers...................................... 37
2.1 Introduction ...................................... 37
2.2 Propeller curves ............................... 39
2.3 Analysis of propeller flows................ 42
2.3.1 Overview of methods .................... 42
2.3.2 Momentum theory......................... 44
2.3.3 Lifting-line methods....................... 45
2.3.4 Lifting-surface methods................. 46
2.3.5 Boundary element methods.......... 49
2.3.6 Field methods................................ 50
2.4 Cavitation......................................... 51
2.5 Experimental approach.................... 54
2.5.1 Cavitation tunnels.......................... 54
2.5.2 Open-water tests........................... 55
2.5.3 Cavitation tests.............................. 56
2.6 Propeller design procedure.............. 56
2.7 Propeller-induced pressures ............ 60
3 Resistance and propulsion ......... 62
3.1 Resistance and propulsion
concepts................................................. 62
3.1.1 Interaction between ship and
propeller................................................. 62
3.1.2 Decomposition of resistance......... 65
3.2 Experimental approach.................... 68
3.2.1 Towing tanks and experimental
set-up..................................................... 68
3.2.2 Resistance test.............................. 69
3.2.3 Method ITTC 1957........................ 71
3.2.4 Method of Hughes(cid:133) Prohaska ........ 73
3.2.5 Method of ITTC 1978.................... 74
3.2.6 Geosim method of Telfer............... 75
3.2.7 Propulsion test.............................. 75
3.2.8 ITTC 1978 performance
prediction method................................... 76
3.3 Additional resistance under
service conditions................................... 80
3.4 Simple design approaches............... 83
3.5 CFD approaches for steady flow...... 83
3.5.1 Wave resistance computations..... 83
3.5.2 Viscous flow computations............ 90
3.6 Problems for fast and
unconventional ships.............................. 91
3.7 Exercises: resistance and
propulsion............................................... 95
4 Ship seakeeping........................... 98
4.1 Introduction ...................................... 98
4.2 Experimental approaches (model
and full scale)......................................... 99
4.3 Waves and seaway.......................... 101
4.3.1 Airy waves (harmonic waves of
small amplitude)..................................... 101
4.3.2 Natural seaway ............................. 106
4.3.3 Wind and seaway.......................... 109
4.3.4 Wave climate................................. 4.2
4.4 Numerical prediction of ship
seakeeping............................................. 117
4.4.1 Overview of computational
methods................................................. 117
4.4.2 Strip method.................................. 121
4.4.3 Rankine singularity methods......... 127
4.4.4 Problems for fast and
unconventional ships.............................. 130
4.4.5 Further quantities in regular
waves..................................................... 132
4.4.6 Ship responses in stationary
seaway................................................... 132
4.4.7 Simulation methods....................... 134
4.4.8 Long-term distributions.................. 136
4.5 Slamming......................................... 138
4.6 Exercises: seakeeping..................... 146
Discourse: hydrodynamic mass ............. 148
5 Ship manoeuvring........................ 151
5.1 Introduction ...................................... 151
5.2 Simulation of manoeuvring with
known coefficients.................................. 152
5.2.1 Introduction and definitions........... 152
5.2.2 Force coefficients.......................... 153
5.2.3 Physical explanation and force
estimation............................................... 158
5.2.4 Influence of heel............................ 163
5.2.5 Shallow water and other
influences............................................... 164
5.2.6 Stopping........................................ 164
5.2.7 Jet thrusters.................................. 165
5.2.8 CFD for ship manoeuvring............ 166
5.3 Experimental approaches ................ 169
5.3.1 Manoeuvring tests for full-scale
ships in sea trials.................................... 169
5.3.2 Model tests.................................... 175
5.4 Rudders............................................ 177
5.4.1 General remarks and definitions... 177
5.4.2 Fundamental hydrodynamic
aspects of rudders and simple
estimates................................................ 181
5.4.3 Rudder types................................. 188
5.4.4 Interaction of rudder and
propeller................................................. 190
5.4.5 Interaction of rudder and ship
hull.......................................................... 193
5.4.6 Rudder cavitation.......................... 195
5.4.7 Rudder design............................... 200
5.4.8 CFD for rudder flows and
conclusions for rudder design................ 201
5.5 Exercise: manoeuvring..................... 203
6 Boundary element methods........ 207
6.1 Introduction ...................................... 207
6.2 Source elements .............................. 209
6.2.1 Point source.................................. 209
6.2.2 Regular first-order panel ............... 211
6.2.3 Jensen panel................................. 215
6.2.4 Higher-order panel........................ 218
6.3 Vortex elements ............................... 223
6.4 Dipole elements ............................... 226
6.4.1 Point dipole................................... 226
6.4.2 Thiart element............................... 227
6.5 Special techniques........................... 229
6.5.1 Desingularization........................... 229
6.5.2 Patch method................................ 230
7 Numerical example for BEM........ 236
7.1 Two-dimensional flow around a
body in infinite fluid................................. 236
7.1.1 Theory........................................... 236
7.1.2 Numerical implementation............. 237
7.2 Two-dimensional wave resistance
problem .................................................. 238
7.2.1 Theory........................................... 238
7.2.2 Numerical implementation............. 241
7.3 Three-dimensional wave
resistance problem................................. 242
7.3.1 Theory........................................... 242
7.3.2 Numerical implementation............. 247
7.4 Strip method module (two
dimensional)........................................... 250
7.5 Rankine panel method in the
frequency domain................................... 253
7.5.1 Theory........................................... 253
7.5.2 Numerical implementation............. 261
References....................................... 265
Index................................................. 269
Preface
The first five chapters give an introduction to ship hydrodynamics, which is
in my opinion suitable for teaching at a senior undergraduate level or even at
a postgraduate level. It is thus also suitable for engineers working in industry.
The book assumes that the reader has a solid knowledge of general fluid
dynamics.Inteaching,generalfluiddynamicsandspecificshiphydrodynamics
are often mixed but I believe that universities should first teach a course
in general fluid dynamics which should be mandatory to most engineering
students.Therearemanygoodtextbooksonthemarketforthispurpose.Naval
architects should then concentrate on the particular aspects of their field and
cover material more suited to their needs. This book is organized to support
such a strategy in teaching.
The first chapter is an introduction to computational fluid dynamics, and
Chapters 2 to 5 cover the four main areas of propeller flows, resistance and
propulsion, ship seakeeping and manoeuvring. It is recommended that this
sequence be followed in teaching. The first five chapters try to find a suitable
balance for practical engineers between facts and minimizing formula work.
However, there are still formulae. These are intended to help those tasked
with computations or programming. Readers with a practical interest may
simply skip these passages. The final two chapters involve more extensive
formulaworkandaremorespecialized.Theymaybereservedforgraduateand
post-graduate teaching and will help understanding and developing boundary
element codes. Field methods are not covered in depth here, as my colleague
Milovan Peric has already co-authored an excellent book on this particular
topic. I tried in vain to find a similar suitable textbook for boundary element
methods which would be both easy to understand and address the typical
problems encountered in ship flows. As I could not find such a book, I wrote
twochaptersintendedtosupportmeinmyteachingandtobeofuseformany
colleagues.
The book is supplemented by some public domain software written
in Fortran which is available for downloading in source code on
www.bh.com/companions/0750648511. The software consists of small
programsorsubroutineswhichmayhelpindevelopingowncodes.Someofthe
programs have been written by myself, some by Professor So¨ding, and some
by colleagues. Feel free to download the software, but there is no additional
documentationavailableexceptforthein-programcomments.Iwillnotanswer
questions about the software, but you can comment on which programs you
ix
x Preface
felt difficult to understand. We may then either update the documentation or
take the software off the website. There is no guarantee that the programs are
completely debugged and of course neither I nor the publisher will take any
responsibility for what happens if you use these programs. Furthermore, the
software is public domain and you may not sell it to third parties.
Despite all this, I have worked with most of the software myself without
any problems. The website will be updated more often than the book, and
there will be a short read.me file on the web with some information on the
available software.
This book is based largely on lectures for German students. The nucleus of
the book was formed by lectures on ship seakeeping and ship manoeuvring,
whichIhavetaughtforseveralyearswithProfessorHeinrichSo¨ding.Ialways
feltthatweshouldhaveacomprehensivetextbookthatwouldalsocoverresis-
tanceandpropulsion,asshipseakeepingandmanoeuvringarebothinterwoven
strongly with the steady base flow. Many colleagues helped with providing
material, allowing me to pick the best from their teaching approaches. A lot
ofmaterialwaswrittenandcompiledinanewway,inspiredbythesesources,
but the chapters on ship seakeeping and manoeuvring use extensive existing
material.
Thanks are due to Seehafen-Verlag Hamburg for permission to reprint text
andfiguresfromtheManoeuvringTechnicalManual,anexcellentbookunfor-
tunately no longer in print. Thanks are due to Hansa-Verlag Hamburg for
permissiontoreprinttextandfiguresfromGermancontributionsinHandbuch
derWerften XXIV.
Countless colleagues supported the endeavour of writing this book by
supplying material, proof-reading, making comments or just discussing
engineering or didactic matters. Among these are (in alphabetical order)
Poul Andersen, Kai Graf, Mike Hughes, Hidetsugu Iwashita, Gerhard Jensen,
Meinolf Kloppenburg, Jochen Laudan, Maurizio Landrini, Friedrich Mewis,
KatsujiTanizawa,GerhardThiart,MichelVisonneau,andHironoriYasukawa.
Mostofall,ProfessorHeinrichSo¨dinghassupportedthisbooktoanextentthat
he should have been named as co-author, but, typically for him, he declined
the offer. He even refused to allow me to dedicate this book to him.
I then dedicate this book to the best mentor I ever had, a role model as a
scientist and a man, so much better than I will ever be. You know who.
Volker Bertram