Numerical Investigations of a Hydrodynamic Interaction between two Floating Structures in Waves

Numerical Investigations of a

Hydrodynamic Interaction between

two Floating Structures in Waves

J.A. Pinkster and I.N. Dmitrieva

Report Oktober 1999

Transactions of the Third international Conference in Commemoration of the 300-1h Anniversary of Creating Rùssian Fleet by Peter The Great, 3 - 9 June 1996, St. Petersburg, Russia, Volume 2, ISBN 5-88303-071-8

TU Deift

Faculty of Mechanical Engineering andMarine Technology Ship HydromechanicsLaboratory

t,

transactions of the Third International Conference

.'.-. '?'

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St.Petersburg State Marine Technical University

of the 300-th Anniversary of Creating Russian Fleet

Feter the Creat

3-9 June 1996

-.y

in Commemoration

'SI,. 45 t,5

CRF-96

1996

Volume 2

-.

St.Petersbùrg, Russia

4

r-:

SLP

b. Statt Manne T«hakal Uiiverity

CRF-96

Transactions of

the

Third International Confereice

in Commemoration

of the 30G-du Anniversary of Creating Russian fleet by

Peter the

Great

3-9 June 1996

VolUme 2

ISBN 5-88303-0714

_Ocn6rMTy

CONTENTS

Organizers ...n..pe.fl.eee 11

-Grcetlags to Perticipant of the Third late louai Conference

.'3OO Yeiirs of Russian fleet" (CRF-96)

List of øoyars, OkohiItcys and DUma's Dyaks Who11o4 PsrtkMted Adaption

of the EdIct (1696) on Creation of theRegular Russian Heet (In Ran). 15

'Peter the Great" Medal

Statute of the Memorial Jubilee Medal."Petertbe Great" 17

Laureates of "Peter the Great"Medal 17

Results adProspectsoÎ internatiÓnulCo-operation Lu tb Sphere nl

Marine Educution, Shipbuilding and Shipping

VOLUME I

Reports

R.V.Thompsoa Safely and Marine Transport... V.A.Pos*nov Scientific and Engineering Society of Shipbuiiders

Named after Academician A.N.Krylov (in Russian)

24

Symposium "History of'Shipbuilding and

Fket"

...

SectiOn 1 "General: Aspects of History ofFleet"

R.C.Wbittcn Admiral of the Fleet of the Soviet Union Sergei O. Oorshkov -and the Rise of Soviet Sea Power

F. aellec Baltic: the Worldwide MaritimeHeritage of an Inner European Sea M. Coleman Russia and America: Balancing t'he Account ooks front tnore than

a Century of Maritime Trade . ...

R.C. Whitteib A Civilian Organization for theSupport at-American

Maritime interests

-V-. von Wir Garzyuskl The White Movement under the Andrew Flag 192C-24 (in Russian)

SP. Rudaya Creation of Medical and Sanitation _{Service in the Russian} Fleet

(In Russian)

147

V.D.Doce&Lo St.Petersburg _{- the Marine Capital of Russia (in Russian)}

156

SectIon 2 "History of_{Sblpbnlldbig"}

161

F.M'.Walker The Russian _{Imperial Yacht 'Livadia"}

161

L.R.Amfllokhjey, _{W.B.AN11IJOIIjCV,}

V.M.Ggeeapreas L.Eùler - to the Fleet (In Russian)

167

E.V.Kutcheryko, Formation._{of the Russian Shipbuilding School}

(In Russian)

176

&A.Mbov, W.B.AmfUokIg,,

_{LM.Me Sireamliness}

of the Ships of the Peter's Fleet (In Russian)

Igl

N.P.Mazaeva, E.V.Kutcberyùo,,

W.B.Amfilokh, influence of Ptculiarjtje,

of the Section-Area

_{Distjbtj0 of Histoc}

Ships on the Friction _Resistance (in Russian)

lU

A.A.Pngaby,,s.A.J0,

_{Some Aspects of theHistory} of 'Submarine_{Creating(In Russian)}

195 V.1. Alezantho,, _{MK. Glozmne}

Investment of Admiralty Shipyard to Creation and Development of_{Russian Underwater Navy}

(in Russian) ₂₀₄

V. Yn.Lelzermaa,_{Development of 'Shipbuilding Technology}

on the Russian Shipyards

...20?

Section 3 "HIstory_{of Marine Weapons"}

20$ A.l.Mk ¡(orov, S.G.Proshkin, A.G.Boysrsky _{History of Mine}

Weapons Development 'in the Russian _{Navy (in Russian)}

20$

LS.Kolobkoi, Stages

of Development of Mine and Contra-Mine Weapons (In Russiañ)

E.N.Mgev, _{V.T.Tcben)oiJqrgy On the Scientific 'Provision'}

of the Problem on Submarines' Ballistic

Rockets Launch by the Scientists of 'the_{Navy Academy} (inRussian)

VE.Fedoro, Development of Optic Means of_{Observe In the Russian Fleet}

(in Russian) ' '

'

SectIon 4 1-listery_{of M'nrlee Edneatlog"}

- __________

G.C.Broae,kgky Admiral_{'S.Makarov's Marine}

Teaching (in Ruasi.,.rn..,.,,,,,.,.Z«

'NN.MaIo, Navy_{Education In Russia}

in 300 years fin

L%. Kozyr'Sanjpl _{of the Navy corporation culture}

'

of the beggining

_o(XXtIj

' ---..i611

'-'4

V.V. kozyr Literature Premium N amed _{after The Count S.A..Stroganov"} in lheRussian Navy (in Russian)

265

M.A.Mikhailiv, I.N.ßaranova, A.V.Starkov _{Information System Rusian fleet}

inthe Russian-Japincese War (in Russian) ₂₇₃ M.H.Thkrry Rok of Joseph Conrad ¡n the Historkgraphy of Shipbuilding

and Navigat_n

216

Symposium "Marine. Ecology"

_zu

A.V.Afanasyev Economic and Ecological _{Aspects of Fluid Cavitation Treatment}

in Ships Power Enginecring(in Russian.) _US

VM .Drowosekov, T.N .Shatilovis,._{S.O.Grlgòrieva, A.Lkamburoya}

Prospects of Sanatori um Improvement on t he Bah ic Sea Shore (in Russian) 293 M.L. Zaîérman On, límportance_{of Underwater Vehicles for Preservation}

of Ocean Biological Resourses

297

L.S.keser, V.N.Psbenia _{Engineering Aspects of Sea Fleet Ecological} Improvement (in Russian)

.305 Si .Krolenko H ydroecological _{Safety During Tim ber-CargoTransportation}

...

(in Russian)

3L6 R.R.Mikhaileako Ecological Estimation of the Influence of the Dike Complex

(in Russian)

.321

VJ.Reuhayak Fuel-Aqueous Emulsions: _{New Theoretical Aspects of Application}

(in Russian)

.332

M.A.Spiridonov, A.E.Rybalko Marine_{Geoecology as a New Trend}

of Investigations (in Russian) ₃₃₉

V.A.kudalk Geoact ive Zones as a Generator o Planet Emergencies and Disasters (in Russian)

345

V.A.Riidalc, E.LMdjko, Geoacth'e_{Zones and their Influence on Human}

Health and State (in Russian)

Synipun. LJisderk,,at.

E)ynainic Objects"

'V.N.PyIa, Underwater Technical'_{Means for World' Ocean Research} and Development (in Russian)

A.V.AwI.sky On' the New Views_{and Investigations in Acoustics.}

for Underwater Facilities (in Russian) 390

V.M.CavrøovConttol Algorithms of Research AU Vs.Drifting on Pre-Sèt Depths 39*

YuJ.Zhukov, M.A.komarov The Questions of Constructing Expert System for

Training a User of Navigating-Manager Complex of Mobile Objects (in Russian) 410

Y.S.Kinpnev, Y.P.Ogurtsov, A.KJ1limouo _{Portable Echo Sounder}

with Discrete Indication (in Russian) ₄₁₆

L.N.Uahenln, V.M.Krasaykh, Y.! .Sauaiko, Characteristic Equal ions and Software for Investigations of Underwater Vehicles Tanspor-t

and Energy Characteristics (in f(ussian) 424

SympQsiu. "Marine Artificial Intelligence Systems

437

V.LAlexandrov D.M .Rostovtscv, A.P. M atlakh, YuLNechaev, V.!. Póiako,

The InteUlgence System of Analysis and Prediction of Tankers Seaworthiness 437

V.E.Baltrashevich, D.V.Vvanov Consulting Expert System with Fuzzy Logic 443

V.1.Borslievlch, W.L.Okinili,, VN.Sidorenco A Method of Integral Estimation

of the State öl Complex Systems by L-fuz7y Sets Approach 449

Y.Bertrnni On the Feasibility of Fully-Automatic Ship Operation ₄₅₅ A.V.Boukhaaoìky, A.LDegtyarev The înstrumçñta) Tool of Wave Generation

Modelling in Ship-Borne Intelligence Systems ₄₆₄

S.A.Dubovik, YJ.Nechae, Algorithm of Stability Analysis Based on the Method of Functional Actioñ on. the Ship-Borne Intelligence Systems

In Real Time Scale ₄₇₀

A.LGalkovlcb Using of Methods of Artificial intelligence for the Decision of

a Problem of a General Arrangement of a Vessel ₄₇₃

T.A.Gavrilova Human-Centered Approach toComputer-Aided Knowledge

Engineering

₄₀

Yu.LNechev Ship-Born intelligence Systems: Conception and the Special

Features of Information, Calculation and Measuring Technology _4$9

V.D.Rot!aaova, LEFedotaev, N.D.Iuaevk Computer-Aided _{Implementation}

of the 6Duer Airborne Operationally ConsultingExpert System investigative Prototype

AX.RidInsId The Usageof Artificial Neuronal Nets for _{the Decision of}

e Mukialzernatjve:pjerp Recognition ₅₀₇

A.V.Radinnkl, V.A1yadkIa Artificial Neuronal Nets

Yu;LSIek Design of intelligent Control Systems of Underwater

Dynamic Objects _.515

S.V.SutUIo, S.V.Yegorov A Submarine Manoeuvring Simulator _{as Tool}

for Expert and integrated Control Systems ₅₂₅ D.A.Vasunla The Intelligence System Choke of Angle Courseand Ship's

Speed in Storm Conditions

ALA2enk1n, Aa.A.Zeokió Intelligent Control Systems based on Cognitive

Çompuler Graphics _.543

LIáI 01 PartIcipants

VOLUME 2

Reports ₂₄

Seminar "Problems of ships' operation" ₂₄

Y.K.Trounin Problems of Ship's Operation ₂₄ A.A.Loukovnikov New Requirements of 1MO, lACS and Russian Maritime

Register of Shipping ₂₇

SS.Kocbyi Register o. Shipping Activities in Discharge of the ISMC Regulations

(in Russian) ₃₀

A.l.Toporkov New Requirements of Safety olManne Cargo Transportation

(in Russian) _.32

R.L.Reiaer Practice and Appikat ion Prospects of_{the Procedure for Sea-going}

Ships Hull Renovation _.33

G.V.Bavykln, V.K.Trounin Training Marine_{Surveyors in Russia .35} M.A.Kouteynikov, V.B.Lipls On the Methodology of Assignment Operation

Restrictions for Ships Considering Their _{Seagoing Possibilities in the Rules of} the Russian Maritime Register of Shipping (in Russian)

G.V.Yegorov System Providing Safe Exploitation_{of Bulk Caniers'} Hulls (in Russian)

H.van Kehupeina, J.Piakste Computer Aided instructions (CAl) Program for

Load Line Assignment (freeboard) Ca(cuJatIonL....,..,,,,

Symposium "Ship design and production" ₇₁

O.V.Vzarenkov, A.S.Roganov, VJ.Sokolov Provision of Accuracy of Ships'

Hulls Shape during their Making up on the Formation Place (in Russian) 71

A.LVcylkuuskays, A.R1îirnashev Classi Vicution Algorithm for Safety Supply

of a Damaged Ship (in Russian) _7$

LA. Kujik Cartes Algebra Applying in Knowledge Base of Intelligence Systems

(In RussiOh) ₈₇

N.V.AIeshln, V.STaradonow, L.P.Volkov, D E.!offe,, A.P. Yegorov,

V.F.Zubakhin, V.E.Meshcberyakov, Yu.V.Polyakov Manoeuvering Tests

of a Vessel Equipped with Rotor-:Rudders(in Russian) ₉₆ V.V.Vasllieva, S.VShkado _{The internal Waves and their Influence on}

Moving Body's Hydrodynamics ₁₁₀

G. Goryausky On e Propeller Operation in a Closed-Tube Modelling 117

V.LJinklne Hydromechanic Problems of Seagoing Tug Barge Systems 124

VS. Taradonov BetzZhukovski Coefficient_{and Theory of an Ideal Wind}

Turbine with Horizontal and Vertical Axes (in Russian) 127

A.V.Boukhanovúy, L.JJeopatoùkbia Statistkal Estimai ionof Extreme Waves

In Storni ₁₄₂

LG.Novlkoy Calculation Methodfor Multislit Chenal of Hydrojet Propulsor

(In Russian) _14$

V. Bertram Economical Aspects of Jumbo Container Vessels 151

ASePOtthOy Application of System Approach for Offshore Technical

Complex Design ₁₅₈

Y.Yoshlda The Optimall Setting of a Planing Craft's Chine Une. ₁₆₄ H.KevaIag, J.Plnkaaer Design Optimisation _{of a Fast Monohull 175} J.Lbtewalk, I.SPolipaaov Upgrading the Performance of MarinePropulsion

Plants of Ships Built in the 1980's _1*6

Yu.V.Colovesbkla, N.LTi1ijkoy _{influence of Mechanic-Corrosion}

Exploitation Factors on the Hull Crack Stability (in Russian) ₁₉₉

Symposium "Ship Hydrodynamics _and

_Dyssmics"

₂₀₃

ASb. Ahkinthe,

_{Ye. N. Srrkia loptimal Contra-Rotating Propellers Design....2ß3}

Vi. AIe,androw, M.K.Glozmaii, L.L.VlshRevsky Propellers with Shifted Blade Connection as Means of Decreasing of Vibration and Improving

of The Service Quality of The Transpt t Ships 221

W.L Amfdo&hiyev, LA. Barba,iel, N.P. Mazayea The Optimization of Slot

Injection of Polymer Solutions for the Flat Plate. 230 L.S. Aitjushko', W.5. Amphilokblev Similarity Criteria for Turbulent Flow

of Dilute Polymer Sølutions ¡n Pipes and Problem of Drag Reduction Scale-Up...237 V.L.Releaky, S.V.MordacevOn Capsizing Probabilityof a Ship Due to

Breaking Waves Action 247

eitram Past,, Present and Future in Ship Hydrodynamics 259

Beukeknan Fluid Momentum.in Ship Hydrodynamics 268 SD.ßògatyrev, O.DShlshkina, VV.Vasilieva Experimental Investigation of

Opportunity of Internal Waves Inducing by Drifting Iceberg... A.V.ßoukhanovsky,A.B. D yarey Nonlinear Stochastic Ship Motion Stability

in Different Wave Regimes .296

I.N.Dinitrievs, V.V.Maxinsov, LS. Nuadnerinteraction Effects between.a Set

of Floating Bodies and Waves 307

B.F.Drouuo,, B.A. Barbanél Development of Large-Scale Surfacing Models 'Tuna" for the Research of Boundary Layer Control Methods .322 A.SLGotmaa The Comparative Criterion in Deciding on the Ship Hull Form

with Least Wave Resistance .332

V.M.Greenpress, E.P.Lebedev Thruster Controllable Pitch. Propeller BladeOutllne 344 S.Guaana Simulation Method of Ship Parameters Optimization 346

U.V.Guuie Numerical Simulation of BodyFluid Interactions. Basic Concepts

Models and Tools, Applications.

J.Hjduk The Application of Ship Handling Simulators for Training

oíManoeuvring

L.K.Kobyaski, J.Nowldd Prospects of Training Ship Masters and Pilots

on Physical Manoeuvring Simulators 368

A. M.KracM Resistance and Propulsion Tests with Systematically Varied

Modd Series. The A-, B-, C- and D-Series. .379

LG.Latorre High Speed Cavitation Tunnel Project for Waterjet/Propeller

Research. Initial Design and CFD Study 397

LV.Lavreaev Ship Collision with a Freak Wave at the Aguihas Current...

LJ.Lopstoukhln, VA.Rothkov,_{A.V.Boukhanovsky, A.B.Degtyarev}

Stochastic Simulation of the Wind Wave Climate ₄₂₂

A.G.Lyakhovitsky Influenceof The Ship Hydrodynamics on Development

of the High-Speed Vessels of the Transient-Regime_{of Motion 432}

S.V.Mordachev, A.V.FeIdIIIaII On Calculation_{of a Probability of Assumed}

Situation Realization ₄₄₂

Yu.I.Nechaev _{Problem of Uncertainty in Hydrodynamic Experiment Planning}

453 J.A.Pinkster, LN.Dimlrieya Numerical Investigations of a Hydrodynamic

Interaction between Two Floating Structures in Waves ₄₅₇ A. Ponumarey, V. Ihoy, A. Bagiinin, V. Bochagov,_{V. Sidorov Application of}

a Complex of AutomaticallyControlled Interceptors for Improvement

of Propulsive, Seakeeping and Maneuvering Characteristics of High-Speed Craft 479

V.P.Sokolav, S. V.SUtulo Study of the Seakeeping of a Fast Displacement

Catamaran Equipped With Above-Water Bow _{Antipitching Fins 487} S. VSutulo Computer Simulation of Three-Dimensiónal _{Manoeuvering Motion}

of a SWATH Ship ₅₁₅

V.V.V*isflie'va, A i.Shkadov, TN&oIsyeva Thin _{Pycnocline Hydrodynamic}

Influence on a Body in Fluid of Finite Depth ₅₂₈

List òíPit1dpaats. ₅₄₁

ORGANISERS

St. Petersburg. Staté Marine Technical University under the support of

UNESCO, "Admiralty Shipyards" State Enterprise, Russian Maritime Register of Shipping, Krylov Rearch and ScientificSociety.

Address: MTU, 3 Lotsnianskaya Str., St.Petersburg, 190008, Russia

Phone: (812): 1140761., Fx. (812)1138109 Edltedby Dr. Alexander B. Degtyarev Mr. Evgenyi V. Labzin Dr. Serge V. Sutulo Dr. VasÌIy K. Trounin

INTERNATIONAL COMMIITEE

Chairman Prof. D. Rosto1sev - Rector of the MTU, Russia Dr. V. Alexaadrov Director General of Admiralty Shipyard State

Enterprise, Russia

Prof. A. Badran - UNESCO Deputy Director, France

Rear-Admiral F. Bellec - Director of the Paris Maritime Museum, France Prof. S. Ka*tner - Professor at Bremen Technical Higher School, Germany Prof. L. Kobyliáskl - President of the Board of the Foundation for Safety of

Navigation and Marine Environment. Protection, Poland Prof N. Mars Chairman of the European Co-ordinating Committee for

Artificial Intelligen, University of Twente, Enschede, The Netherlands

Mr. N. Reshetov - Director General of the Russian Maritime Register of Shipping, Russia

Prof. L. Perez Roja. Director of the Department in the Madrid Institute of

Naval Engineers, Spain

Prof. H. Soding - Professor at the Institüte of Shipbuilding of Hamburg University, Germany

Mr. F. Wa&er - National Maritime Museum, Greenwkh, UK

GREETINGS TO PARtICIPANTS

OF THE THIRD INTERNATIONAL

_CONFERENCE

"300 YEARS OF RUSSIAN

FLEET " ,(CRF..96)

Dear participants of the Conference, ladies and gentiómeni

On behalf of the organisers I_{am glad to welcome you to the Third final} International Conference "300 Years of Russian Fleet".

We are assembled here in the city founded by the distinguished reformer of Russia, creator of the Russian Fleet Peter the Great in the year of the glori-ous jubilee.

Peter's timo witnessed remarkabió achievements, brilliant military victo-ries, promoted the national self-consciousness enforcement and Russia entering

the European community.

History of the Russian Fleet is versatile and instructive. It ¡s filled with examples of courage and heroism of the_{seamen, talent and high: skill of} ship-builders, scientists and inventors.

The present stage of development .of Russia and its fleet in particulär has much in common with the Peter's epoch. Following the traditions of the great reformer, we arrived to this forum to underline again our aim. at co-operation, good will and consolidation of efforts in development of science and practico of shipbuilding and operatión.

I wish all the participants fruitful _{discussions and contacts, good}

un-pressions of staying in St. Petersburg.

Chairman of the Iateraatlojjal Committee Rector of MTU, Professor . . .

. D.M. Rostovtsev

"PETER THE GREAT" MEDAL

STATUTE OF TIlE MEMORIAL J1JBLLE

"PETER THE GREAT"

The medal "Peter the Great" was established by the International Working Group recommendations in. 1991. It is given by: the Internatiönal Association "Petronauka" (Petroscience) founded by St.Petersburg State Marine Technical

University to all those who had make a considerable contribution to the

development and support of the ship science and technology and for teaching marine specialists.

The International Jury Is organised for considering proposals of candidates. The awarding with the medal and Certificate takes placeopenly closely to the birthday of Peter theGreat on May 30 (June 9, the New style).

LAUREATES OF "PETER THE GREAT"

1992

Dr.-Eng. W.BLENDERMAN Institut ftirSchlffbau der Universitat Hamburg, Germany

Prof..A.N. HOLODILIN StPetersburg State Marine Technical

University,, Russia

3 Prof. L.LKOBYLINSKI Technical University of Odanek, Poland 4.. Prof. D.M.ROSTOVTSEV Rector of St.Petersburg State Marine

Technical. University, Russia Mr1 A.V.RUTSKOY VIce resident o. Russia

Adm. Y.E1SELIVANOV Captain of 'Leningrad Naval Base, Russia Arcbpdest VLADIMiR :SOROKIN Orthodox Theological Academy and

Smnary.StPetersbur& Russia

& Rear Adilral VN$TSHERMKOV Vk4v1yor øfStPtersburg. Russia

Eng. F.M.WALKER National Maritime Museùm, Greenwich, UK IO.Prof. V. von WIREN-GARZYNSKt City University of New York, USA

1993

Dr. J.BAKKER Director, Scheepvaartmuseum, the Netherlands Mr. 1.A.BYKHOVSKI Captain of the ist rank (ret.), Russia Prof. D.FAULKNER University of Glasgo, UK

Mm. LV.KASSATONOV, Russia

Mrs. N.V.KOLYAZINA Director, the Menshikov Palace Museum, St.Petersburg, Russia

Mr. A.P.KOROLEY Director General, Centrai Marine Design Bureau "Almaz", St.Petersburg, Russia

Prof. SN.KOVALEV Designer General, Centrai Design Bureau for Marine Engineering "Rubin", St .Petersbürg, Russià

Mr. F.MAYOR Director-General, UNESCO

Dr. B.VPLISSOV St.Petersburg State Marine Technical. University, Russia lO.Prof. Y.LYOITKOUNSKJ St.Petersburg State Marine Technical

University. Russia

1994

i. Dr. V.A.ALEXANDROV Director General of the "Admiralty Shipyards" State Enterprise, Russia

Mrs. N.L.DEMENTYEVA Director of the museum

"'Peter and Paul Fortress", St.Petersburg, Russia Mr. Y.M.GUTKIN State Design Institute "Sojuzproektverr,

St.Petersburg, Russia

Prof. SKASTNER Hochschule Bremen, Germany

Prof. A.G.KURZON St.Petersburg State Marine Technical University, Rusíia

Rest Mm. N.N.MALOV St.Petersburg, Rûssia

Prof. N.P.MURU Naval Engineering High School, St.Petersburg, Russia Prof. V.A.POSTNOV 'St.Petersburg State Marine Technical

University, Russia

9. Dr. V.K.TROUNJN River Ship Design Centre mc, St.Petersburg, Russia lO.Mr.LF,TSVETKOV Institute of the History of Science and Technology,

St.Petersburg, Russia.

1995

I. Prof. N.V.ALESHIN St.Petersburg State Marine Technical University, Russia

Prof. V.D.DOCENKO Naval Academy, St.Petersburg, Russia

Adm. V.V.GRISHANOV Captain of the Leningrad Naval Base, Russia Mrs. N.A.KISELEVA St.Petersburg State Marine Technical University,

Russia

Mr. E.V.LABSIN St.Petersburg State Marine Technical University, Russia Mr. N.A.RESHETOV Head of the Baltic Inspectorate of the Russiàn

Maritime Register of Shipping, St.Petersburg, Russia Prof. E.NROSEN WASSER St.Petersburg State Marine Technical

University, Russia

Prof. D.E. SLOGET Academic secretary at. the Institute of Marino Engineers, UK

Prof. A.V.YALOVENKO Rector of the State Maritime Academy, St.Petàrsburg, Russia

lO.Prof. V.E.YUKHNIN Head and General Designer, Severnoye Design Bureau, St.Petersburg, Russia

1996

Mrs. L.Ya ØAGREYEVA Secretary of Krylov Research and Scientific. Society, St.Petersburg, Russia

Prof. W.BEUIOELMAIj Dem University of Technology1 The Netherlands Mr. G.A.C}fERj4ßJflN Marine writer, St.Petersburg, Russia

Acad. AI.N.CHILINGAROY Vice-Speaker of the RussianDuma

Mrs. M.COLEMAN Director of Russian-Ameijcancultural centre, USA Mr. A.V.KOUTEYNIKOV General DesIgnerand Director of Marine

Engineering Bureau "Malakhit", St.Petersburg,

Russia

rV4.LANENKO Director General of Nikolaev Shipyard

named after "61 Communars", Ukraine

Pusf. V.ftMATSKIEWJCZ St.Petersburg State Marine Technical University, Russia

Aàn. A.N.MELNIKOV Chief of Regional Maritime _{Center, St.Petersburg,} Russia

lO.Prof. V.M.PASRIN Director of the Krylov Shipbuilding_{Research Institute,} St.Petersburg, Russia

I1.Mr. V.A.PEEVALOV Principal designer of crúlser "Peter the Great", "Severnoye" Design Bureau, St.Petersburg, Russia 12.Prof. LV.RÂKITSKY St.Petersburg State Marino Technical University,

Russia

13.Pvof. A.A.ROUSSBSKY Krylov Shipbuilding Research Institute, St.Petersburg, Russia

14.Prqt. GIP.TtJRMOV Rector of the Far East _{Polytechnic, Vladivostok,} Russia

I S.M,. L.LYERMASH Principle Designer of_{Soviet "mosquito fleet" of the} Second World War, St.Petersl,urg, Russia

l6.Reas.Ad. LG.ZAKHÀROY Head of the First Centrai Naval Construction

Research Institute of the Defense Ministry, St.Peteraburg, Russia

NUMERICAL INVESTIGATIONS OF A

}ffflRØDjAMJC INTERACTION BETWEEN

TWO ILOATING STRUCTURES IN

_WAVES

:

j. PINKSTER*.

Delfi Univers4)'ofTeehnàiogy, The NEtherlands:

Lis. DM11 k;IEVÄ**

St Petersburg Siate Marine Technical University, Russia CRF'196-Conference: 3-9-June1996..St.Petersburg, Russia

Abstract

For several years numerical, methods have been available -(or

evaluating the wave diffraction load& on targe volume fixed or floating

offshore structures such as storage tanks, gravity and

sezuisubmersibic

platforms, etc. These techniques have been further extended

_{in order that}

mean and slowly varying wave drift responses might be assessed In the_case

when the geometry of the body

_{is complex, interaction effects between}

bodies become important

In this paper one of thé versión's of the pro'añi'DELFRAC

_for

multibodies which is based on- the three-dimensional potential theory is

investigated. In ordér to solve theproblern use is máde of discrètisation of 'a boundary integral equation on. the submerged surface of the body by means of-using of a source distribution.. The boundary intégral procedùre is _based on an assumed constant distribution of the source strength over each pene! into which the surface is divided. ::

For such solutioñ a;great number of panels are required, especially

because of several- bodies"i teractions. As an éxample of such an interaction effect two structures which àre floating in waves in each other's vicinity have been selected.

Professor, Prof., Dr. ir. Associate Prof., Ph.D.

The hydrodynamic coefficients of eaéh body and hydrodvnarnic _interaction coefficients are calcúlated for several configurations of bodies. Results are obtained fór. two closely spaced floating bodies free to move independently. The dimensions of bodies are similar. Comparisons with experimental and

theoretical results of other authors are discussed. Some conclusions _about

the use oía 3D diffraction metho.d and especially the version of DELFRAC program. for multibodies are given.

Computation times strongly depend _{on the number of bodies. For the}

case of a single body (cylinder or box with approximately the _{same total}

number of panels ) the calculation of forces and motions including drift

forces takes lO minutes

_{per frequency and per body. For the case of}

calculations of two bodies' interaction the time increase to one hour. If it is

not necessary to calculate the drift forces using the pressüre integration

method the time of calculation can be decreasedto 20 minutes per frequency.

i Introduction

In ofThhore industry the use of several structures, floating in each other's

vicinity, is a rather common practice. In such case the behaviour of each of

these structures is influenced, besides possible restraints due to mooring connections, by hydrodynamic interaction effects due to the neighbouring

structure.

The above problem has been discussed bya number of authors. First of them is Q. van Oortmerssen j I Ji, whom the method of cálculation of first order

quantitlà was developed on a base of 3D technique. R.E. Taylor

and J.

Zietsman 2 J have proposed the method of interaction analysis which as based on combining a finite élement idéalisation of the fluid region close to a

body with a boundary Integral representation of the far field behaviour

They have highlighted that such a method can be selected as an economical numerkal techmque Further development of this problem has been _{made by}

D.M. Ferreira and C.-HLee [ 4 1. They have represented the effective

method of the calculation of drift forces on two independent close bodies

Lastly a method to obtain the solution of the

equations in the unknown source strengths has been worked out by LA, Puikster [6] This method as

based on successive approximation of source strengths

Nowadays the first problem is to improve the existing methods and to do its faster and niore effective. The second problém is to Obtain _{more data for a} verification of results of computattoils and to analyse data obtained

In order to solve the last problem the present investigation has been carried out. Next aim of our investigations is to show that 3-D diffraction methods generally can be applied to such cases and for instance, the computer code DELMULTI j suitable for suchinvestigations.

458

I

t.

In The present study, attentiOn

_{is paid to interaction effects}

_{In the}

hydrodynamk reaction forces of first order as well as the drift forces, acting on oscillating floating bodies.

2 Theoretical Aspects

Following to G. van Oortmèrssen._.[ 1.

J: and to J:A Pinkster

E 6 J, consider two rigid floating bodies of arbitrary shape in response to excitation

by a long crested regular wave. The flúid is assumed to be ideal and

irrotational.

Use is made of a rectangular Cartesian

_{coordinate system The orIn of}

the coordinate system is located on the free surface of the fluid The z - axis is vertical and positive upward The oscillating body motions are described

in local coordinate systems of each body Each local _{system is connected}

with the centre of gravity

The free surface is defined in the same way as in all potenUaF cases The flow field rs characterized by a velocity potential

t1(xí, X2, xa,t)= p:(xt,X2,

q=_iw[(.po

+)+

+:

where

Tite potential function 'p as a function of coordinates can. be_{separatedfttto} contributions from all modes of motion of both bodies and from the Incident and diffracted wave potentials:

- wave amplitude;

(') -the scattering _{wave protenliâldueto motion offirst body In}

the j-th mode;

- the complex amplitude ofj-th mode of motionfor

the.firstbody;

- the scattering wave potential dúe tornötion of second body in the j-th mode;.

-. the complex amplitude ofj-thmode of motion for the second body;

According to potential. theory, the described potentias satIsfy tu.

Laplace equation in combiflation with several known boundary oendidons. The pressure In any point òf fluid can bC calcúlätèd wIth both otCfltiaSÍ of each body:

2{(

+ + +

(3)

The hydrodynamic reaction force in the k-th mode on the first body is follows:

F(»

=

po)2 e'°'

Ji (y1 Q)

y(2))

nkdS

(4)

and on the second body:

= po)2 e_Lwt

ic(,j

+

;(2))

(5)

As it can be seen froni the equations (4)

_{- (}

5 ) and according to G. van

Oortmerssen the following coefficients may be defined: = - PO2 _k (I)dS;

Qk?

= -

k (2) lS'

kJ2 P02

L)

nk'PJdS;

(6)

= - poet II n ,1O)

_dS:'

These coefficients define the force components due to appropriate motioñ

according.to the following tule

- the force of. k-mode 'on S(» dúe to motion in the j-mode. ófSW;

Q*)

_{- the force of k-mode on}SO)due to motion in the j-mode of5(2),_etc

Therefore, the coefficients Qii.P and Q(2) ' are connected with' body's interáction, wheñ the coefficients PkJ» and Pkj( describe the 'forces due to

own bo4y motions. : '

Using á well-known way. all coefficientscan be separated: into real ançi imaginary parts as follow;

Pkj«) o)2a3J

+ibkJ°;

p(Z)

₊

Q&j» =re2

4»

+ =

2dkJ2 +

i

(7)

460

where a andbkj are well-known added mass anddamping coefficients;

4JkJ and e are in-phase and out-of-phase interactlòn coefficients.

As it is shown by Oortmerssen, for the case of muitibòdy's motions thé

interaction coefficients satisfy the symmetry relátionshlps, i.e.

el.. (1)_A (2).

aicl. 'jk

(2)

Ckj

Cik

it ls.obvlous that in the case óf single body's motions the coefficients4 and

arc equalto zero. .. :

The.relationships (8) can be an effective basIs [br Che king calcul4tlons of the iüteraction effects of two bodies.

3,

1 quátions f Motion of TwoUnconfltéd Bødies

We describe here the equations of motions for the severál bodies to

illustrate clearly the mechanism of thè.iñteractiónbetweén the bódies as well as hydrodynamic interaction coefficients

According to potential theory the équations ófmótiòfls can be written

as follow: '

first body

EHoez:(Mij(i) +

aj')_ io1q»

+

'c»Jyj

+

(_w2d1j(» _1oec41°'];,..= X'(». second.body

+

ag1):_ lø;b12

csj(2)j;

+

-

Ic1j(!Jyj =.X';

461 (8.)

where Mij - the inertia matrix of body; - the dimensional added mass,.

the dimeñsional damping coefficient;

d1- inphase hydrodynamic.interáction coefficients ,yielding a force in i-mode dueto moti ou' in thej-mode of a.àéighbour

structure; . 's

r

- out-of-phase hydrodynamic interaction coefficients, yielding a force in i-mode due to motion in the j-mode of a neighbour

structure;:. :

. '

X1 wave exciting force.;

-complex amplitudeofmotion.in the j-mode of first and second bodies respectively.

The affix (I) or.(2) serves to identify the bOdies, while the subscripts

i and

j denÑà the modes of motion. .. . . .

In order to calculate mean 'drifts forces, acting

_{on bolli bodies, the}

pressure integration method is applied See Pinkster_{[ 7] The pressure field}

(3)15 kown nfter'solving a first order problem.

4; Tile Computer Code

In order to solve the potential' problem of multibody interaction the

computer code DELMULTI. was, developed at the Delfl University of

Technólógy. This code is one of .thà versions of the piogram DELFRAC

which is based on the application of 3D linear diffraction _{theory Basically}

the.probléms are. defined as boundary value problems where the 'solution is

found by using a panel method. Using'this.code'a calculation _{c'an be made}

for two or several bodies which may oscillàte in waves with zero forward

speed or be fixed:Rclative locations of each 'bodycan be arbitrary.

For evaluation of the Creen function and its derivatives the MIT

routine is used f 8 J The input data which include a description of each body arethe. same as iii the case of the program, DELFRAC for_{one bOdy [.3.].'}

'5 Qakudations rand Cònejusiois

5 1 Description of Bodies

:Ili.:der.r to. analyse the results of cömputations and'.especially the hydrodynanuc interaction between two structures, floating in waves, two

bodies have been selected (accoiding

to the results of computations and

experiments of G van Oortmerssen f I]) cylinder;

'box.

Thesbodies are:shownin'.figuresl -2, 'includIng the panels. in figure ¡

the meshes of two bodies from rjJ

bòstto

side are shówn.. One of

configurations of these bòdies is shown ¡n 'figure 2.

Fig.l

The bottom view of two bodies,

total numbers of panels ofa cylinder and abox. are 392 and 432 respéctively.

Fîg.2

The distance between the centres of two bodies is 152.75 meters,

the ratio distance / draft ¡s 5.Ofl.

463

The.Urst:body.Is afloating cylindér of radius R = 47.9 m. The draft of the cyhnder is 30 m The centre of gravity is located at the waterline of the cylinder The wetted surface of the body is discretized by 98 panels per

quadrant or 392 foi the whole body Use is made of quadrilateral panels but In the bottom triangular panels are applied close to the centre of cylinderas

can be seen in figure 1

For the calculation of drift forces 7 waterline

elements have been applied per quadrant

Thé s cand body is a' rectangular barge of 109.7 m length, 101.4 m

breadth with a draft:of 30 in. The calculation point ïs

at gravity entre

located at the waterline The wetted surface of box as discretized by 108

numbers quadrilateral panelsper quadrant or 432 for the whole body. For

calculation of the drift forces Il waterline elements per quadrant are apphed

The table below shows the number of panels, per wave length at

different periods for the two investigated bodies.

Tab. I

Number of panels' per wavelength for two bodies

From this table il can be seen that the mesh refinements for the two bodies

are satisfactory. Even for the highést frequéncy the number of panels per

wave length is sufficient in order to calculate the first order loads and

motions in accordance with existing practice

_{However, for accurate}

calculation of second order loads these numbers of panels for the highest

frequency are not enough. For. this case. smaller paiaels are preferable.

In figure 2 one configuration of the two bodies as shown Calculations

were camed out for three distances between bodies See table 2

Túb. 2 Distances between':bodjes

464

Frequecy yad/èe 005. ' 0.3., 0.5 0.7 0.75

Period, ': sec 125.6 20.93

i256

' 8.971 8.373

Wàve 1àngth

'm'.

24609.6 :683.4

246.1' 125.55 109.37

98*4 l=.IO'6&m]: 2308.6 .64.11'

.74.77 23.09 ' '26;93 '11.78 13.74

126

11.97 Box 108*4 [l9.l4.m]. 26925 Separation .distance,..m 50' '100 150

Distancebetween the centres ofbodies,ni 152.75 202.75 _252.751

Litio distauce/draft, - . . 5.092 6.758' 8.425

52 Calculation Conditions

In our numerical investigation we obtained results for regular waves. In this case, the amplitude of wave is! m. The circular frequenciesof oscillation of the incident waves _{are varied from 0 05 to 0 75 rad/sec corresponding}

to wave periods of 125.6 to 8.373 seconds. This raüge corresponds to the

range offrequenciesapplied by van Oortmerssen[ .

The calculations were carried out for one wave direction- 180 degree All of results were obtainedfor_{a..water.depth.of 220 meters and forone}

draft of 30 meters. .

The program of investigation of bodie?

_{interaction consisted of}

comparisons of the following data:

hydrodynamic. coefficients (surge and heave added mass and damping

coefficients) calcùlated for single bodies _{by using the maiñ DELFRAC}

program;

the same hydrodynainic coefficients obtamed _{by taking into account the} interaction effects and using the version of DELFRAC for multibodies,

.*hich: are equal. to zero for the

case ola siñg1ebody i

drift forces on each body. calculated by a pressure illtegration fflethod.

5.3 Descriptions ofDimensionsof

_{Output Data}

Output files of all versions of DELFRAC contain dimensional values.

In order to compare the results they _{were made non-dimensional according}

to the data of van Oortmerssen. (: I _{j in the following way:} Non-dimensional wave frequency

_o'=

P/g,

where _{is. dimensional circular wave frequency;}

1(2) is the length of second _{body (in our case it is a box);}

g - gravity acceleration.

Non-dimensional hydrodynamic coefficients_{are given in the table 3.}

Defiñition Body I (cylinder) Body II .( box Non-dimensional added mass

A1k"

/(y(i))

' 1k

Non-dimensional dampiñg

B/(.pV(» Ig/1°)

B'/(pV

Jg/i)

Non-dimensional interaction coefficients: coupled added mass

(1) /(pV(1))

coupled damping coefficients

e)/(pV(2) ,jg/I(2))

in which:

p is the massdensity of water, g is gravity acceleration;

IC') or 1(2) are the diameter of a cylinderortbeIcngth of abox

respectively; ..

V) or '1(i) are the volumes of displacement ófatìrst orsecond

bodies respectively

añd other values are described earlierin the equàtlons of motions.

5.4 Discussions of the Results

We obtained the results f. calculations using the multibody version of DELFRAC which was created at the Deift Unwersity of Technology This program .DELMULTI is based on the.Sohition of a 3D diffraction problem

and takes into account interaction effects. This can be made by using thò

velocity potential which. consists the contributions from allmodes. of motion of both bodies and from the incident and diffracted wave fields.

As the first step of the investigations we obtained the hydrodynamic

forces on two bodies separately using the main 3D diffraction program

(see

description of this program ref. j 3]). These results were comparedwith the

results of van Oortmerssen obtained by using the 3D

diffraction code

466

d2

/(pv(2))

Tab. 3

Non-dimensional hydrodynamic coefficients

developed in MARIN. The good correlation between the results for single and rather simple bodies has been obtained with the using of the different 3D codes even for the cases in which different number of panels have been used. The last can be seen from the table 4.

Tab.4

Comparison. ofthe total number of panels

In fig. 3 through fig.

LO the results are given of calculations

of

hydrodynamic coefIicientsof.two: bodies - cylinder and box separately for

the smallest separation distance between them, where the

.èffects of

interaction

are more significant

Agreement between the results

of

DELFRAC and f van Oortmerssen. is found tobe generally very good for

all coefficients.

On the same graphs the results for the single bodies áre a1s9 shown. By

comparing the graphs, it. can be seen that th interaction effects are more

important for the horizontal mode than for the vertical mode and also for

the ràther high frequénòies. In our calculated case the coefficients diverge

above the non-dimensional wave frequency w' > I . No effects due to the

presence of the neighbouring structure are observed at the lower range of

frequencies. _1.0

o

0 .5 10 1.5 2.0

'!(UW

Fig. 3. Surge added mass coefficient A'11 of the box as a fimction of a nou-dimensional wave frequency 0'.

467

.--.Ç

DEtMAC 0 CLCwva,si., a E,ÍaMWCSfNIø

... !.

(C(LF*C1 Olstanc 152.7km J_w',

a

L .8

'X

. .6 H a .4 .2

Type of a body DELFRAC van Oortmerssen [Ii

Cylinder

.3fl

. .. 92

1.75 :1.50 X 1.25 LOO 1.00

p.75

N-.

.25

Vedc& Added mass coeffident of a box with total 432panélá

o

0 .5 10 1.5

468

20 2.5

Fig. 5. Surge added ma coefficient A! _{of the cylinder as a function of} on-dimensiona1 wave frequency w'.

. Q ö-- ØILFRAC O a.. . - 5l.b(DELffiAC) Dstance15Z.75m. :

¼

9.

.w a

r

G----o OELFR.0 C OaisMsu.n . O Eub,s.I,Dsrn.I .... IgIIbOOLFRAC) -5m -' DIstance 152.

1_cl.

o .5 10 1.5 2.0 & = wxi4 .Q(l).l g)

Fig. 4. Heave added mass coefficient A» of thé-box as a flinótion of₈

ñon-dimensional wave frequency w'.

1.0

.8

ucoeffldento1 a cyOnd9rta

.2

o .5

Fig,. 6. Héave addéd mass coefficient A'aPefthe s a

tìofl of a.

nOiÑIiflieflsiOñal wave frequency o'.

4otizontai dwnpingc000ddeflt of abox wmrtøt6I432p*n.Is

10

Fig. 7. Surge damping. coefficient: B'Ø« of the box as a iiPn

of

an»i-diníensional wave frequency w'.

469 Is ... DELFRAC O-.o.ø CWLØPIVnInI*I D.: .. (OWAAC) . . Dstanco 152.75 rn . ¡ .

i

r

---i

.8

4

.2

o

Verticat damping coeffident of a box wIth total 432.panels

470 u

!'IJ."kj.1ii

'Q'

D D o

_?øD

PC' N. U.IOELFC o

£z.u.;;--.

it

iii

mr

'o -st

r

i

Distance152.75 m

iil

J.

o .5 10 1.5

Fig. 9. Surge damping coefficient D'i' of the cylinder as a function of a

non-dimensional wave frequency '.

o .5 10 15

w'x'I()c»Ig)

Fig. 8. Heave damping coefficient B'a, of the box as a function of a

non-dimensional wave frequency (0'.

.4 2 .4 .2 o -.2

Verticai dasflping coefflctent of a cyUndar$th totat 392 panee

io

471

10 1.5

1.5

Fig IO Heave damping coefficient W»fthecyIthdetas*Tiinction oft

non-dimensional wave frequency '

Figúres ii -14. give an impress on of theinteractioneffectswhtch exist

for the muhibody case The hydrodynamic interaction coefficients i1

and q

are gwen in non-dimensional forms.

4ydrodynasnlc intOraction coeffidentS between a cyHnder and a box

w' = x4 (PP

Fig. 1.1. Hydrodynansic interaction coefficients d1112' and dÍl" between the

box and the cylïdcrasa t%mctonàfaion-dimensional wave frequency w'.

D.. 1ap.*.rivuuá'

o--0

*.D

m '.0 DIstanc 152.7

w'

u...-uoaFR*cQ 4. aFPACMmL. G---O c.t c..._... q fta.iOsiuus.in (!PL)

1__n(bui

t52.75

I-,.

,i.,

.5 o

Pfddynamc kfleractlon çoeffld8rtt&.betwae cVra bôx

472

.5.

.

t0

1.5

Fig. 13. Hydrod'nainic interaction coefficients d'3? d'3? between the box and the cylinder.as a fimctii ofa nondùnen.iona1 wave frequency w'.

Fig. 12. HydrÑIyfl'nc iac6c cccits e'11» and e'11

between the

box and the cyb eTfiwctio of a r"& flsionaI wave frequency w'. a cyllndar.and a box 4-e- -+

G. Oc---,

V. L-DtsanCeT75m V

-.1

.3

.2

o

0 _.5

Hydroctynamic interaction coetficIent between a Cylinder and a box

10 ₁₅

'xI(lt»Ig)

Fig. 14. Hydrodynamic interaction coefficientsC3? and e,.» between the box

and the cylinder as a function of a non-dimensional wave frequency w'.

From the calculations presented in figures 11 throúgh 14 it can be seen

that the hydrodynamic _{interaction coefficients really have the symmetry}

relationships. These coefficients _{depend strongly on the presence of the} moving neighbouring structure over a wide range of fréquencies, _especially the coefficients dq which _{are not equal to zero at all frequencies calculated.} Following van Oortmerssen [1], _{it can be concluded.that,. where the effect of}

the neighbouring structure on the added mass and damping diappears _at

very low frequencies, this is not the case for th interaction forces. Even at

low frequencies, _{a structure will experience hydrodynamic forces as a result}

of the motions of _{a nearby floating structure. These forces appear to be in}

phase with the motion of _{the neighbour, since for frequencies approaching}

zero the coefficients

_{tend to zero. For the}

_{case of hydrodynamic}

interaction forces the _{correlation between calculated and measured values}

are reasonable.

For the second and third

_{configurations of the bodies the}

_same

COnC1USÎOS can be drawn _{as in the previous case. A significant influence of}

interaction efTects is observed for the horizontal hydrodynamic _coefficients and no influence_{on the vertical hydrodynamic coefficients}

The influence of the distance between two interacted bodies _{can be seen}

from figures 15 - 16. As expected, _{the interaction forces decrease with}

increasing distance between the two bodies. For this distance which is 8.425

times to compare the draft of _{bodies, the interaction still exists however. Of}

course, it is interesting to continue the calculations in order.to obtain the

results for other bodies'

_{configuration. However, the computing cost}

increases significantly.

The last part of

_{our investigations is related to the calculation ofdrift}

forces which were obtained for_{several cases of wave heading - 180, 225 and} 270 degrees. In order 'to illustrate _{the influence ofthe wave heading on the} horizontal drift forces the_{graph 17 is shown.}

to 0.8 0.6 0.4 02 o

.t0

X X _ 0.5 II

Horizontaladded mass coefficient of a cyanderwith total.392 panels

0 05 lO is

Fig. 16. Influence of .the separated distance between two bod the auge

damping coefficieflt of the cylinder versus a non-dimensional frequency.

474

-v

Dt 152.75 ie

G---O 0t. 252.76.rn

----

SiØe body ffiAC)

I

-

\jzr

-P:

L

I : \1

\!

cqì-a

r1

G----E3 Dt 152.75 m øC Dist. 202.75 rn a --- Dt 252.75 in 9---VSebodyELRAC)

i

'J

-

--o 0.5 1.0 1.5 ₍₀

exI(PIg)

Horizontal danin9 coefficient of a cybnder

Fig. 15. Influence of the separated distance between t bodies o the 9uge

added mass coefficient of the cylinder versus a non-dimcàùnal wa frequency.

This influence can be seen at practical frequencies when the drift forces can even change direction. Ths facs is explained by complex interaction between two bodies and by significatif influeticc of wave elevation which dominate in drift forces. _Horizanta

_{thft facce oi a}

_{cylinder, ast. 50 m (by DELMULTI)}

o -250 G--- o Longit. ( 50 m. 1800) Longit ( 50 rit 225°).

a- -

Longit. (50 flL 270° } I

S'

1 s. -T

---L.

-500 0.2 0.4 0.6

, ris

Fig 17. Influence of wave heading on the longitudinal drift force transfer

function of the cylinder vs a wave frequçncy.

In figures 18

19 the results of comparisons of drift forces are

presented. The results of the calculations by Ferreira and Lee (see ref. (4] )

are shown in the same figures as well as experimental points of van

Oortnierssen. On comparing the. cunes good agreement was found between

the theoretical results of Ferreira and Lee and those obtained using the

program DELMULTI.

In summary, it can be concluded that the using of 3D methods for the

calculation of first order and mean second order forces in the interaction

case can give quite satisfied results.

Computation urnes strongly depend on the number of bodies. For the case of a singIe body (cylrnder or box with approximately the same total number of panels ) the calculation of forces and motions including drift

forces takes 10 minutes per frequency and per body. For the case of

calculations of two bodies' interaction the time increase to one hour. 1f il is

not necessaiy lo calculate she drjft forcà using the pressure Integration

method the lime of calculation can be decreased

to 20 mInutes per

frequency. h is necessasy to underline that for the multibody case a

computer 1DM - 486 DX with freqùency 66 MHz and 32 Mb 1.AM Is used. For calculation of a single body a computer ¡BM - 386 DX with frequency 40 M}k and 16 Mb RAM is used.

O)

°02

ir

0.6

01

-0.25 -0.50 -0.75 0.2

Horizontal nondimenslonaf drift farce on the rectangular box

0.8

-Heading

-

2700

476

Fig. 18. _{The longitudinal drift force transfer function of the}

rectangular box versus a wave frequency for the several calculation conditions.

Total horizontal nondimenslonal _{drift force, wave dir. 180°}

S---. Comp. surf, moth.

rn- -rn Near field moth.

a _{Far field moth.}

a _{Experkn. Oortmorson}

'

Exporn. Loken

' CalcuL by DELMULTI

v--- y _{Comp. surf, moth. 1792 pan.} Comp. surf, moth. 816 pan.

rn-- s Near field moth. 1792 pan.

+ Near field meth. 816 pan.

a _{Expern. Oortmorson}

'---e Calcul by DELM(L11

0.6 w, ris

Fig. 19. _{Total longitudinal drift force transfer function obtained by}

several

methods as a function of a wave frequency.

-0.2

6 Conclusions

The main COnClUSIOnS from._{our numerical. investigations are as follows:}

hnear 3D. diffraction

_{theory is suitable to predict h.ydrodynamlc}

interaction effects betweeñ floating _bodies;

the comparisons of _{computed and measured. values Of hydrodynamic}

coefficients of the bodies and _{hydrodynamic intèraction coeffiòients are}

quite good;

the computed results

_{obtained using the multibody version}

_of

DELFRAC correlate well with _{the results of Other authors}

the biggest interaction effects are observed at rather high frepiencies and can be significant. When two structures have the same size and similar motions amplitudes, it appears that. the hydrodynamic forces due _{to the} motions of the neighbour, can be Of the same order Of magnitude as the forces, induced by the body's _{own motions.;}

in literature only few results it can be found of _{3D calculation of drift}

forces acting _{on two or more bodies, especially when bodies have an}

arbitrary or ship shape. In _{order to havà moré experimental}

_{data for a}

testing of existing computer codes the investigations have tO be

continued. However, some conclusions about. drift forces _{can be made} from our analysis.

Acknowledgment

This investigation _{was carried out during the research fellowship of one} author at the Deift. University of Technology. The author _{expresses. hr deep} appreciation for the possibility_{to work in this field of OffshoreStructures} Hydrodynamics.

References

I. _{Oortmerssen van G. Hydrodynamic Interaction Between Tvo Structures,}

Floating in Waves Il Second

_{Int, Çonf, on Behaviour}

_{of Off-Shore}

Structures, BOSS'79, 28 - 3! Augüst 1979. P. 339 - 356.

Taylor R.E., Zietsman J.

_{Hydrodyntnnjc loading 013 multi-component} bodies_{1/3rd International. Conference BOSS'82, 1982. P. 424 - 443.}

Dmitrieva I.N. DELFRÁC. _{3-D.poze,uia/ theory including wave djffraczion}

and drfl forces acting _{on the s:ruc:ures.11 Description of the program.}

Report M 1017 of the Shiphydrodynamics.Laboratory TU Delft. 1994. Ferreira D.M., Lee C.-H. _{Conpuzatio,, of Second-order Mean wave Forces} and Moments in Muizibody _{hiteraction. II BOSS'94, 7th International}

Conference on the Behaviour

_{of OffThore Srtuctures, 1994. Vol.2,}

Hydrodynamics and Cable Dynamics, Ed. C. Chryssossontidis, MIT. P. 303-313.

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