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Practical Ship Hydrodynamics Practical Ship Hydrodynamics Practical Ship Hydrodynamics Practical Ship Hydrodynamics Volker Bertram Butterworth-Heinemann Linacre House, Jordan Hill, Oxford OX2 8DP 225 Wildwood Avenue, Woburn, MA 01801-2041 A division of Reed Educational and Professional Publishing Ltd First published 2000 Volker Bertram 2000 All rights reserved. No part of this publication may be reproduced in any material form (including photocopying or storing in any medium by electronic means and whether or not transiently or incidentally to some other use of this publication) without the written permission of the copyright holder except in accordance with the provisions of the Copyright, Designs and Patents Act 1988 or under the terms of a licence issued by the Copyright Licensing Agency Ltd, 90 Tottenham Court Road, London, England W1P 9HE. Applications for the copyright holder’s written permission to reproduce any part of this publication should be addressed to the publishers British Library Cataloguing in Publication Data Bertram, Volker Practical ship hydrodynamics 1. Ships – Hydrodynamics I. Title 623.8012 Library of Congress Cataloguing in Publication Data Bertram, Volker. Practical ship hydrodynamics / Volker Bertram. p. cm. Includes bibliographical references and index. ISBN 0 7506 4851 1 1. Ships – Hydrodynamics I. Title. VM156 .B457 2000 623.8012–dc21 00-034269 ISBN 0 7506 4851 1 Typeset by Laser Words, Madras, India Printed in Great Britain by Preface ............................................. ix 1 Introduction .................................. 1 1.1 Overview of problems and approaches ............................................ 1 1.2 Model tests 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 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
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