Eighteenth Symposium on Naval Hydrodynamics (1991) / Chapter Skim
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Nonlinear and Linear Motions of a Rectangular Barge in a Perfect Fluid
Nonlinear and Linear Motions of a Rectangular Barge in a Perfect Fluid
Pages 85-100
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From page 85... ...
on tile free surface. Efficient artificial bou ndary conditions are i~nple~nented tight allow nonlinear and linear si~nulations to be performed over a large number of wave periods.
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From page 86... ...
Even though Sindbad can be run to solve both the nonlinear and linear problems, it was felt that a proper assessment of tile validity of its results required some confrontation with more traditional linear frequency domain models. Comparisons have been made with two such models, one based on matching of eigenfunction expansions Or tile potential in tile three sub-domains limited by a rectangular barge (left, right, and underneatI~)
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From page 87... ...
The pressure i8 assigned constant along tile free surface; it call tI'us be included ill tile function of time city. Witty an appropriate choice of tile velocity potential, taxis r~'ctio~ can be taken equal to zero.
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From page 88... ...
3.3.2 Absorbing beadle Tiff absorbing beacon is a dig zone, si~ilar to that used in Al. Ill taxis zone, tile free surface boundary conditions are '~o~lif~e~l lay ad`li~'g a calming terser.
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From page 89... ...
3.3.3 Absorbi'~g Wave'~aker 'I'l~e al~sorbi'~g beacI' al~ows lo~'g silllu~atiOlis to be perfor~ned in tI`e nu''~erical tank wI~en tI'e generation a~d tIte propagation Of surrace waves are ti~e o''ly co'~cerns. A ~lilficulty al'pears ror tI~e si''~ulation or tI`e rree '~otions Or a body i'~ tI~e ta~k.
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From page 90... ...
(13) r1'1'e potential ~ is the solutions of tile i,al,lace valuation together witty tile free surface boundary conditions a'td tile kinematic boundary co'' |
From page 91... ...
tI~e a,cceleratiott of tI~e bo(ly, XG ~na.y be '1eter'~`i'~ed. 'l'l~e evol~'tio'~ etl'~a.t,i`~ ror tI'e free surface variables (¢,x)
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From page 92... ...
right Or the Charge (l,) I lert (~' -- - see fi'g'''~ ,l.
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From page 93... ...
Isfx ~1 ~ ~ :~ ~ ~ ~ AL 7 SO / SR FiglI[e 4: (;~01~1Pt[lC dC1}I';tIO1'S R) [ 1.I'0 II1~[ il~trgrn.1 e~llln.1.1cl' ~- ~ ~ INS ~ ~ ~ 141CI`1.51.y.
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From page 94... ...
rs) _Integrnl Equntior, (sharp corners)
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From page 95... ...
Fig''re 8. Swa.y trall~fer [ulictio 2.00 E 1.75 E 1.50 _' w 1.25 ~ 1.00 Q :5 0.75 > 0.50 ~c 0.25 O.OC Figilre 10: Itoll tra.'l~rer [tinctioll Sindbad (rounded corners)
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From page 96... ...
6 Conclusion A simulation technique based on tile Mixed Eulerian-Lagrangian method leas been described. It allows the simulation of tile now and tile resulting barge motions to be performed with either linear or fully nonlinear boundary conditions on the hull and on tile free surface.
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From page 97... ...
.0 I;'ig~lre 11: Mel vet ti '''e (~'o',li''ear Si'',''l?
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From page 98... ...
) (l, "t't,'''1'ttIF;ll';'JIt ',r p~<':~.~tit'F, iV;~.v'`n," \~;~- Ili;~, ill ice, l~l'~w;~.r Ace~le'',i' l'''l~lisl~ers, 1~1' '175`1!
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From page 99... ...
The definition of the reflected wave that we give is therefore difficult to interpret is one refers to the Eulerian velocity potential in the fluid domain. However, as we use a Lagrangian specification for the time-stepping procedure, there is no ambiguity for the implementation of the method; we refer to the potentials attached to a marker labeled by its abscissa xc along the reference position of the free surface (that coincides with the x-axis)
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