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Validation of Time-Domain Prediction of Motion, Sea Load, and Hull Pressure of a Frigate in Regular Waves
Pages 82-97

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From page 82... ... The validation study of computed results was carried out by comparing with experimental data from a hydroelastic model of the frigate. INTRODUCTION The predictions of ship motions, sea loads and hydrodynamic pressure distribution over a ship hull are essential components of ship design. Read the entire page →
From page 83... ... of the time-dependent Green function is computed by solving an ordinary differential equation (Clement, 19984. Ship motions, sea loads, and hull pressures predicted by the computer program SEALOADS for the Canadian Patrol Frigate (CPF) Read the entire page →
From page 84... ... In the computer program SEALOADS, a series expansion method is used to achieve an analytical solution of the ordinary differential equations (Qiu and Hsiung, 19994. The linearized radiation force at time t can be obtained from Fi p (t) Read the entire page →
From page 85... ... over the wetted surface forward of the station He VALIDATION An effort was made to validate the ship motions, sea loads, and hull pressures computed by SEALOADS for a Canadian Patrol Frigate in regular waves in the deep departure condition. This took about 25 minutes to compute using 10,000 time steps (At = 0.02 sec.) Read the entire page →
From page 86... ... Motions, Sea Loacis anc! Pressures Selected predictions of motions, sea loads, and hull pressures together with the experimental results in regular waves at the deep departure condition are presented below. Read the entire page →
From page 87... ... This could be because sensor 11 is located close to the stern and the pressure due to incident waves was computed on the instantaneous wetted surface. The wetted surface could change drastically due to the shallow draft at the stern of CPF. Read the entire page →
From page 88... ... . Lc, 40 c'' 30 ~ 20 S 10 1 .4 15, 10 _ _ O ~7 ~=1~ 0.6 0.8 1 1.2 1.4 -- ~ 1~ o 0.6 0.8 1 1.2 1.4 \/L 50 1 1 1 Lo 40 � _ 30 _ _ `u 20 _ _ S 10 _ O 1 1 1 0.6 0.8 1 1.2 1.4 \/L ~ 1 1 1 o 40 _ _ c,, 30 _ _ i~ 20 Ln > 10 _ ~ ~ ~ ~ ~ _ 1 1 1 1.2 \/L 1 .4 Figure 5: Predicted motions and sea loads in regular waves, ~ = 180�, Fn=0.06 (Legend: o experimental, H/~= 1/30; x experimental, H/~= 1/20; SEALOADS, H/~= 1/30; -�SEALOADS, H/~= 1/204. Read the entire page →
From page 89... ... 10 cn i~ > 5 C' ~, 40 c'' 30 ~ 20 > 10 \/L 15 10 1 .4 1 .2 0.8 0.6 - 9~~=~ 0.6 0.8 1 1.2 \/L 15 I 0.6 0.8 1 1 \/L .sn I I _=~'W~ i o 0.6 0.8 1 1.2 .2 _ _ c'' 30 ~ _ _ ~ 20 5 _ ~ > 1C 0.6 0.8 1 1.2 \/L Figure 6: Predicted motions and sea loads 8 O 1 1 0.6 0.8 1 1.2 \/L l regular waves, ~ = 165�, Fn=0.06. Read the entire page →
From page 90... ... 1.4 _ I I I I _ 1.4 1 .2 _ _ 1 .2 1 _ _ 1 ~~ 0 8 ~ x 0 8 02 ~ ~ O X - 02 O O 0.8 1 1.2 1.4 1.6 \/L 2.5 15 _1 1 1 1 ~ _ .~ W~ x � _ ~ X~ ~ 1 1 1 0.8 1 1.2 1.4 1.6 \/L L`, 20 _ _ Lo c~ c~ `u 15 _ _ `~ 1 0 _ _ i~ O ~1 -g >m 1 ~ 0.8 1 1.2 1.4 1.6 0.8 1 1.2 1.4 1.b \/L \/L 20 15 10 5 o 25 20 ~ 15 cn `~ 10 S 5 20 15 10 5 o O I ~ ~ ~ ~1 ~. 0.8 1 1.2 1.4 1.6 \/L c 4C ~ 3C cn i~ 20 Ln > 10 o _, =:=~= _ ~ ~ ~ ~ ~ ~ ~ 0.8 1 1.2 1.4 1.6 \/L 4C 3C 2C ~ 10 ~ I I I I ~ o 0.8 1 1.2 1.4 1.6 \/L 50 _ ~ 40 _ ~== __4 ~ 20 t -- - ~ 3~ Q ~ _ S 10 I I I I n 0.8 1 1.2 1.4 1.6 ~1 _ ~ ~ ~ ~ q -- ~ 1 1 1 1 0.8 1 1.2 1.4 1.6 \/L 50 1 1 1 1 :: ' =~__ C 1 1 1 1 0.8 1 1.2 1.4 1.6 \/L Figure 7: Predicted motions and sea loads in regular waves, ~ = 180�, Fn=0.12 (Legend: 0 experimental, H/~= 1/30; x experimental, H/~= 1/20; SEALOADS, H/~= 1/30; -�SEALOADS, H/~= 1/204. Read the entire page →
From page 91... ... 0.5 _ O l l l l l 0.8 1 1.2 1.4 1.6 \/L 1 .4 _ 1 .2 _ Go JO 0.8 0.6 0.4 0.2 2.5 0.5 O 3 2.5 o (n ~ 1.5 (n Q 2 1 0.5 o 1 .4 1 .2 _ ~ 1 ~ 0.8 1 1.2 1.4 1.6 \/L 0'-~-0.8 1 1.2 1.4 1.6 \/L _ ~ � _ _ _ _ _ _ . ~ 1 1 1 0.8 1 1.2 1.4 1.6 \/L 1 o a' 0.8 (n `u 0.6 0.4 0.2 o 3 2.5 2 o (n a, 1.5 (n i~ Q 0.5 o -O ~Q ~ 1 1 1 0.8 1 1.2 1.4 1.6 \/L Figure 8: Predicted pressures on six sensor locations in regular waves, ~ = 180�, Fn=0.12 (Legend: o experimental, H/~= 1/30; x experimental, H/~= 1/20; SEALOADS, H/~= 1/30; -�SEALOADS, H/~= 1/20) Read the entire page →
From page 92... ... CONCLUSIONS Validation of the computer program SEALOADS on ship motions, hydrodynamic pressures and sea loads has been carried out for CPF. The ship motions, sea loads and hydrodynamic pressures predicted by SEALOADS, in general, agree well with experimental results under the following conditions: a) Read the entire page →
From page 93... ... (19994. Theoretical Manual for SEALOADS version 1.0 - a Computer Program for Prediction of Nonlinear Ship Motions, Sea Loads and Pressure Distribution in the Time Domain. Read the entire page →
From page 94... ... 10 cn i~ > 0.6 0.8 1 1.2 \/L ~, 20 _ _ c'' 1 5 _ _ ~ 10 _ _ >m 5 o 0.6 0.8 1 1.2 \/L 50 _ _ c'' 30 _ _ _ ~ 20 _ _ ~ > 10 _ O ~ ~ ~ ~ ~ ~ , 3.6 0.8 1 1.2 \/L ~ _ _ ~ -- ~ -- ~ ~ 0.6 0.8 1 1. \/L .sn l l ~, 40 _ _ c'' 30 _ _ (a 20 _ _ > 1 0 ~ 0.6 0.8 1 1.2 \/L 1 1 0 40 _ O 1 1 0.6 0.8 1 \/L Figure 10: Predicted motions and sea loads in regular waves, ~ = 135�, Fn=0.12. Read the entire page →
From page 95... ... . _ L~ 40 _ ~ 30 _ cn `u 20 _ Ln S 10 o 4C c,, 30 i~ 20 Ln ~-~-~ -- ~U O ns n~ ~ ~Q 0.6 0.8 1 \/L Figure 11: Predicted motions and sea loads in regular waves, ~ = 180�, Fn=0.20 (Legend: o experimental, H/~= 1/30; x experimental, H/~= 1/20; SEALOADS, H/~= 1/30; -�SEALOADS, H/~= 1/204. Read the entire page →
From page 96... ... A key pu chcal isme is to decide how close hhe uumeucal md expenmenh I resu h ueed to be for hhe ag eemeut to be cousidered, firom a ship desigmer s peu pechve, "sahsfactory" For example, s hhough hhe sms I scale of fig res 5 to 8 makes it dhfficu t to mske a precise quandh hve evaluahou of hhe dhffereuces, it appeau hhat pred cted md meas red loads close to amidships dhffer, by as much as 100% Shou d hhis be cousidered fair, sahsfactory or umsahsfactory, importaut or umimpor mt? Third y, We wou d like to buefly sddress hhe is me of umc rtainty The resu t of any expeumeut or simu ahou is uot a umiqme value, but u hher a u uge wihhiu which hhe res value is located wihh a defiued level of coufideuc While it is well knowu hhat all meas remeutaudcalcuahouare mbjectto umcerh inly, hhis knowledge is uot ofteu u cd m assessmg compausous of uumeucs simu ahous aud resu h of expeumenh Au umcertainty analy is is especially importaut iu any process for validahou of uew simu ahou medhods A fommal umcertainty aus yses wou d also preseut au oppor mity to evaluate qus ity of hhe dah, to idendfy hhe biggestsources of enor audgive dhrechou for fuh re improvemenh iu expeumeut techmques or uumeucal medhods We wouder if hhe auhhou have camed out such au aus ysis or if hhey have plau t do so iu fuh re? Read the entire page →
From page 97... ... (1995) Qu notification of correction of predicted Ed measured tr msfer fun tions for ship motions Ed wave loads R1NA Intemational Conferen e on Ship Motions Ed Maneuv mblity, London Qm, W Read the entire page →

From page 82...

... The validation study of computed results was carried out by comparing with experimental data from a hydroelastic model of the frigate. INTRODUCTION The predictions of ship motions, sea loads and hydrodynamic pressure distribution over a ship hull are essential components of ship design.

Validation of Time-Domain Prediction of Motion, Sea Load, and Hull Pressure of a Frigate in Regular Waves Pages 82-97

Validation of Time-Domain Prediction of Motion, Sea Load, and Hull Pressure of a Frigate in Regular Waves
Pages 82-97