?· WAMIT R USER MANUAL Version 7.2 This User Manual has been prepared for users of WAMIT Version 7.2.…

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<ul><li><p>WAMIT R</p><p>USER MANUAL</p><p>Version 7.2</p><p>This User Manual has been prepared for users of WAMIT Version 7.2.</p><p>WAMIT is distributed by WAMIT, Inc. under a special agreement with the MassachusettsInstitute of Technology. Further information is available from the website shown below.</p><p>The WAMIT software and this User Manual are Copyrighted by WAMIT, Inc., and bythe Massachusetts Institute of Technology. The User Manual can be downloaded from thewebsite without a license.</p><p>WAMIT, Inc.</p><p>822 Boylston St. Suite 202Chestnut Hill, MA 02467-2504USAphone 617-739-4488 fax 617-739-4499www.wamit.com</p><p>01</p></li><li><p>Copyright c 1998-2016 WAMIT, Incorporated and Massachusetts Institute of Technology.No part of the WAMIT software or documentation may be reproduced, translated, ortransmitted in any form without the express written permission of WAMIT, Inc.</p><p>WAMIT is a registered trademark of WAMIT, Inc.</p><p>Intel is a registered trademark of Intel Corporation.</p><p>Windows is a registered trademark of Microsoft Corporation.</p><p>MultiSurf and RGKernel are registered trademarks of AeroHydro, Inc.</p><p>Tecplot is a registered trademark of Amtec Engineering, Inc.</p><p>02</p></li><li><p>TABLE OF CONTENTS</p><p>1. INTRODUCTION</p><p>1.1 WAMIT Version 7</p><p>1.2 Changes introduced in Version 7.0</p><p>1.3 Changes introduced in Version 7.1</p><p>1.4 Changes introduced in Version 7.2</p><p>2. GETTING STARTED</p><p>2.1 Installation and setup</p><p>2.2 Demonstration programs</p><p>2.3 Standard test runs</p><p>2.4 Running Test 01</p><p>2.5 Running Test 11</p><p>2.6 Other test runs</p><p>2.7 Using multiple processors</p><p>2.8 Memory and storage restrictions</p><p>2.9 Modifying the input files</p><p>3. DEFINITION OF QUANTITIES EVALUATED BY WAMIT</p><p>3.1 Hydrostatic data</p><p>3.2 Added-mass and damping coefficients</p><p>3.3 Exciting forces</p><p>3.4 Body motions in waves</p><p>3.5 Hydrodynamic pressure</p><p>3.6 Free-surface elevation</p><p>3.7 Velocity vector on the body and in the fluid domain</p><p>3.8 Mean drift force and moment</p><p>3.9 Zero and infinite wave periods</p><p>4. INPUT FILES</p><p>4.1 Summary of changes in Version 7 input files</p><p>4.2 The Potential Control File</p><p>4.3 The Force Control File (Alternative form 1)</p><p>4.4 The Force Control File (Alternative form 2)</p><p>4.5 Definition of fixed or free modes</p><p>4.6 Body pressure and fluid velocity at specified points</p><p>4.7 Configuration files CONFIG.WAM and .CFG4.8 Filenames list FNAMES.WAM</p><p>4.9 File names</p><p>4.10 File format</p><p>4.11 Uniform arrays of field points</p><p>4.12 Using the optional file BREAK.WAM</p><p>4.13 Assigning RAOS in an external file</p><p>4.14 Evaluating FORCE outputs in POTEN (IFORCE=2)</p><p>03</p></li><li><p>5. OUTPUT FILES</p><p>5.1 The formatted output file (.out)</p><p>5.2 Numeric output files</p><p>5.3 Froude-Krylov and scattering forces</p><p>5.4 Body pressure for the higher-order method</p><p>5.5 Body pressure and velocity at specified points</p><p>5.6 Auxiliary files for hydrostatics (.hst) and external forces (.mmx)</p><p>5.7 Auxiliary output files for the geometry</p><p>5.8 Error messages</p><p>5.9 The log file (wamitlog.txt)</p><p>5.10 The intermediate data transfer file (.p2f)</p><p>6. THE LOW-ORDER METHOD (ILOWHI=0)</p><p>6.1 The Geometric Data File (GDF)</p><p>6.2 Use of the source formulation (ISOR=1)</p><p>6.3 Bodies with thin submerged elements</p><p>7. THE HIGHER-ORDER METHOD (ILOWHI=1)</p><p>7.1 Subdivision of the body surface in patches and panels</p><p>7.2 B-Spline representation of the solution</p><p>7.3 Order of Gauss Quadratures</p><p>7.4 The Geometric Data File</p><p>7.5 Geometry represented by low-order panels (IGDEF=0)</p><p>7.6 Geometry represented by B-Splines (IGDEF=1)</p><p>7.7 Geometry represented by MultiSurf (IGDEF=2)</p><p>7.8 Analytic representation of the geometry</p><p>7.9 Modifying the DLL Subroutine GEOMXACT</p><p>7.10 Bodies with thin submerged elements</p><p>7.11 The Optional Spline Control File</p><p>7.12 The use of default values to simplify inputs</p><p>7.13 Advantages and disadvantages of the higher-order method</p><p>8. ANALYSIS OF MULTIPLE BODIES (NBODY &gt; 1)</p><p>8.1 Input to FORCE (IALTFRC=1)</p><p>8.2 Input to FORCE (IALTFRC=2)</p><p>8.3 Input to FORCE (IALTFRC=3)</p><p>8.4 Parameters in the configuration files</p><p>8.5 Global symmetry indices</p><p>8.6 Output</p><p>9. GENERALIZED BODY MODES (NEWMDS &gt; 0)</p><p>9.1 Input Files</p><p>9.2 Using DEFMOD with the Low-Order Method</p><p>9.3 Using the DLL Subroutine NEWMODES</p><p>9.4 Hydrostatics</p><p>9.5 NBODY Analysis</p><p>10. USE OF IRREGULAR FREQUENCY OPTION (IRR &gt; 0)</p><p>10.1 Input parameters</p><p>10.2 Automatic free-surface discretization (IRR=2 and ILOWHI=0)</p><p>04</p></li><li><p>10.3 Automatic free-surface discretization (IRR=3 and ILOWHI=0)</p><p>10.4 Automatic free-surface discretization (IRR=3 and ILOWHI=1)</p><p>10.5 Assigning different values of IRR for NBODY&gt;1</p><p>11. MEAN DRIFT FORCES USING CONTROL SURFACES</p><p>11.1 Control surface file (CSF)</p><p>11.2 Low-order control surface file</p><p>11.3 Higher-order control surface file</p><p>11.4 Combining two control surface files</p><p>11.5 Automatic control surfaces</p><p>11.6 Output</p><p>12. SPECIAL EXTENSIONS</p><p>12.1 Internal tanks</p><p>12.2 Trimmed waterlines</p><p>12.3 Radiated waves from wavemakers in tank walls</p><p>12.4 Bodies and wavemakers with vertical walls</p><p>12.5 Bodies with pressure surfaces</p><p>12.6 Integrating pressure on part of bodies</p><p>12.7 Bodies in channels of finite width</p><p>13. THE F2T UTILITY</p><p>13.1 Definitions of radiation and diffraction outputs</p><p>13.2 Acquiring input data for F2T with WAMIT</p><p>13.3 How to use F2T</p><p>13.4 Output files</p><p>13.5 Options 5 and 6</p><p>13.6 Theory</p><p>13.7 Dimensional input and output data</p><p>14. COMPUTATIONAL TOPICS</p><p>14.1 Number of equations (NEQN) and left-hand sides (NLHS)</p><p>14.2 Solution of the linear systems</p><p>14.3 Temporary data storage</p><p>14.4 Data stored in RAM</p><p>14.5 Data stored in scratch files</p><p>14.6 Multiple processors (NCPU&gt;1)</p><p>14.7 Modifying DLL files</p><p>14.8 Reserved file names</p><p>14.9 Large arrays of field points</p><p>15. THEORY</p><p>15.1 The boundary-value problem</p><p>15.2 Integral equations for the velocity potential</p><p>15.3 Integral equations for the source formulation</p><p>15.4 Discretization of the integral equations in the low-order method (ILOWHI=0)</p><p>15.5 Discretization of the integral equations in the higher-order method (ILOWHI=1)</p><p>15.6 Removal of irregular frequencies</p><p>15.7 Integral equations for bodies with thin submerged elements</p><p>15.8 Mean drift forces based on pressure integration</p><p>05</p></li><li><p>15.9 Mean drift forces using control surfaces</p><p>15.10 Internal tank effects</p><p>15.11 Pressure surfaces</p><p>APPENDIX A DESCRIPTION OF TEST RUNS</p><p>A.1 Truncated vertical cylinder (TEST01)</p><p>A.2 Irregular-frequency removal (TEST02)</p><p>A.3 Mean drift force and moment (TEST03)</p><p>A.4 Body in a channel or near a wall (TEST04)</p><p>A.5 Multiple bodies (TEST05)</p><p>A.6 The ISSC Tension-Leg Platform (TEST06)</p><p>A.7 The ISSC Tension-Leg Platform (TEST07)</p><p>A.8 Elastic column with generalized modes (TEST08)</p><p>A.9 Spar with three strakes (TEST09)</p><p>A.11 Higher-order analysis of circular cylinder (TEST11)</p><p>A.12 Irregular-frequency removal (TEST12)</p><p>A.13 Multiple bodies (TEST13)</p><p>A.14 ISSC TLP (TEST14)</p><p>A.15 Semi-Sub (TEST15)</p><p>A.16 Barge with bending modes (TEST16)</p><p>A.17 Cylinder with moonpool (TEST17)</p><p>A.18 Elastic column (TEST18)</p><p>A.19 Catamaran barge (TEST19)</p><p>A.20 MultiSurf Barge (TEST20)</p><p>A.21 Spar with three strakes (TEST21)</p><p>A.22 FPSO with two internal tanks (TEST22)</p><p>A.23 Radiated wave field from a bank of wavemakers (TEST23)</p><p>A.24 Motions of a hinged vessel (TEST24)</p><p>A.25 Air-cushion vessel with pressure chambers (TEST25)</p><p>APPENDIX B FILE CONVERSION USING THE UTILITY V6V7inp</p><p>APPENDIX C USING THE WAMIT-RGKERNEL INTERFACE (By J. S. Letcher, Jr.)</p><p>06</p></li><li><p>Chapter 1</p><p>INTRODUCTION</p><p>WAMIT Version 7 is a radiation/diffraction panel program developed for the linear analysisof the interaction of surface waves with various types of floating and submerged structures.WAMIT Version 6.4S, which is described in a separate User Manual [29]1, performs theextended analysis for the second-order solution in bichromatic and bidirectional waves,including sum- and difference-frequency components.</p><p>Version 7 has been developed to exploit important features of contemporary computingsystems, especially in the PC environment. For systems with relatively large random-accessmemory (RAM) and with multiple processors (CPUs, also known as cores), Version 7 isdeveloped to take advantage of these features with substantial reductions of the computingtime in many applications. Another important development in this context is the 64-bitoperating system, which is essential for data access with large RAM.</p><p>The remainder of this Chapter gives a general description of WAMIT Version 7, andchanges made from earlier versions. Users of earlier versions should refer particularly toSections 1.2, 1.3 and 1.4 which list the changes introduced in Versions 7.0, 7.1 and 7.2.A mark in the left margin, as on this line, is used throughout this User Manual to callattention to changes in Version 7.2.</p><p>WAMIT includes options to use either the traditional low-order panel method or a moreversatile higher-order method based on B-splines. The description and use of WAMIT forboth the low-order and higher-order methods of solution has been unified as much aspossible. Most of the input and output files are generic, applicable to both methods inthe same form. The principal exception is the Geometric Data File, which specifies thegeometry of the body surface. To simplify the understanding and use of this User Manual,chapters are organized separately for generic information common to both methods, andfor specific information which refers to either the low- or higher-order method separately.</p><p>In Chapter 2 a tutorial description is given to help users get started using WAMIT inthe PC/Windows environment. The examples described in Chapter 2 are for the simplestcontext of a single body.</p><p>1Throughout this User Manual numbers in square brackets refer to the references listed after Chapter 15</p><p>11</p></li><li><p>Chapter 3 defines the various quantities which can be evaluated by WAMIT, and whichare contained in the output files.</p><p>Chapter 4 gives more detailed information regarding the generic input files, includingthe Potential Control File (POT) and Force Control File (FRC) which specify the principalnon-geometric inputs for WAMIT. Also described in this Chapter are the files fnames.wam,config.wam and break.wam, which are useful to specify input filenames and various pa-rameters or options.</p><p>Users of Version 6 should note that some changes have been made which are intendedto make the input data more consistent. As a result, Version 7 may require modificationsof old input files, as explained in Section 4.1. Appendix B describes the utility v6v7inp,which has been prepared to automate the conversion of old input files.</p><p>Chapter 5 describes the output files, which contain the principal data computed by theprogram as well as log files, error files, and auxiliary files which provide useful informationregarding the geometry of the structures.</p><p>Chapter 6 describes topics which are specific to the low-order method. These include thelow-order Geometric Data File (GDF), which defines the coordinates of panel vertices, theuse of the source formulation to evaluate the fluid velocity and second-order mean pressureon the body surface, and the analysis of bodies with thin elements such as damping platesor strakes.</p><p>Chapter 7 describes topics which are specific to the higher-order method, including thesubdivision used to represent the body surface and velocity potential on this surface, andthe representation of the potential in terms of B-splines. Alternative methods for definingthe body geometry are described including the use of low-order panels, the use of B-splinesto provide a higher-order continuous definition, the use of explicit analytical formulae, andthe use of MultiSurf geometry files.</p><p>Chapters 8-12 describe several extended features in WAMIT. These include the analysisof multiple interacting bodies (Chapter 8), the use of generalized modes of body motionwhich can be used to describe structural deformations, motions of hinged bodies, etc.(Chapter 9), and the use of a method to remove the effect of the irregular frequencies(Chapter 10). Chapter 11 describes the procedure for evaluating the mean drift forces andmoments by integration of the momentum flux on a control surface which surrounds thebody in the fluid. Chapter 12 describes additional extensions to include the dynamics offluid in internal tanks, trimmed waterlines, radiated waves from wavemakers, interactionsof bodies and wavemakers with vertical walls, applications where part or all of the bodysurface consists of free surfaces with oscillatory pressures, a simplified method to includeor omit parts of the body surface when integrating the pressure force and moment, andthe analysis of bodies in channels of finite width.</p><p>Chapter 13 describes the utility F2T (Frequency-to-Time domain) which is used totransform the linear WAMIT outputs to the corresponding time-domain impulse-responsefunctions.</p><p>Chapter 14 describes various computational topics including temporary data storage,numbers of unknowns, and input parameters, to provide a qualitative basis for estimating</p><p>12</p></li><li><p>the requirements for RAM and hard disk storage, and for estimating run times. Instructionsare provided for using multiple processors and extended RAM to reduce run times. Section14.7 outlines the procedure for modification and use of .dll files to describe the geometryand generalized modes. Section 14.8 lists the reserved filenames used by the program.Section 14.9 describes an alternative procedure to evaluate field pressures and velocitieswhen the number of field points is very large.</p><p>A brief outline for the theoretical basis of WAMIT is presented in Chapter 15. Reference26 contains a more complete review of the pertinent theory.</p><p>A list of relevant references is included after the final chapter. Appendix A includes de-scriptions of the standard test runs. Appendix B documents the use of the utility v6v7inpfor converting Version 6 input files. Appendix C describes the use of the interface betweenWAMIT and the MultiSurf kernel.</p><p>1.1 WAMIT Version 7</p><p>WAMIT is a radiation/diffraction program developed for the analysis of the interactionof surface waves with offshore structures. WAMIT is based on a three-dimensional panelmethod, following the theory which is outlined in Chapter 15. The water depth can beinfinite or finite. Either one or multiple interacting bodies can be analyzed. The bodiesmay be located on the free surface, submerged, or mounted on the sea bottom. A varietyof options permit the dynamic analysis of bodies which are freely floating, restrained, orfixed in position. In addition to the conventional case where the bodies are rigid, andmoving with six modes of rigid-body motion, WAMIT permits the analysis of generalizedmodes to represent structural deflections, motions of hinged vessels, devices for wave-energy conversion, etc. Part or all of the boundary surface can be defined as a free surfacewith an oscillatory pressure, as in the case of an air-cushion vehicle or oscillating watercolumn.</p><p>The flow is assumed to be ideal and time-harmonic. The free-surface condition is lin-earized (except in Version 6.4S where the second-order free-surface condition and bodyboundary conditions are imposed). We refer to this as the linear or first-order analysis.Mean second-order forces are included in this analysis, since they can be computed rig-orously from the linear solution. The radiation and diffractio...</p></li></ul>


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