Cookbook Dp402

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RetroHULL_BuB_1v PARTIALLY PARAMETRIC HULLFORM VARIATION

Daehwan Park FRIENDSHIP SYSTEMS park@friendship-systems.com

1 INTRODUCTION This cookbook introduces how to use a CAESES project file RetroHULL_BuB_1v.fdb for hullform variation from mothership base. This project file has been used in several ship yards and design offices to perform hullform optimization in the combination with CFD soft-wares in their use. Practically it is also used for

saving the man-hours in the ordinary hullform variation works. For example, after scaling the main dimension afterbody setup like changing boss position and fitting the propeller diameter or moving up and down stern profile to secure the propeller clearance.

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2 TIPS BEFORE START

1. Model Refresh Disable

Inserting imported data (i.e. offset groups, curves, surfaces an so on)

Changing several parameter values

Any case when the geometric update is not needed.

2. Pin On/Off

When entity must stay selected in the Object Editor

3. Go easy to the entity location

Move the cursor on the entity name in the edit box.

Select the entity in the pop-up box.

The selected entity is opened in object tree.

4. Shut off STL

During setting the form variation, shut off the scope for trimesh variation.

Since the data size of surface is larger usually, long duration for form variation will be needed to

obtain surface variation result.

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3 IMPORT DATA

Open retroHull_Bub.fdb file. In the provided file KVLCC2 data like boundary curves, offset groups and

surface mesh are contained. For the new design, all the corresponding data must be imported again.

Import boundary curves in IGES format.

o abdyFos

o fbdyFos

o BulbProfLow

o BulbProfUpp

o Stem

o SternProfLow

o SternProfUpp

Fig 1 : Boundary curves

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Import offset groups in SHF format.

o Aftbody

o Boss

o Bulb

o Forebody

o Stem

o SternOH

Fig 2 : Offset groups

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Import surface mesh of STL format.

This STL data are needed to be exported usually to CFD software which should be connected to

CAESES.

o bossHole

o Deck

o Hull

o Transom

Fig 3 : Trimesh from STL import

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4 SETTING MOTHERSHIP DATA

Insert boundary curves in the curve containers.

Insert all imported boundary curves in the corresponding boundary curve containers under the scope of

1_MotherShip. For example, the imported fos curve of afterbody can be contained like Fig 4.

Fig 4 : Insert the imported boundary curve in the curve container

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Insert offset groups in the offsetgroup containers.

Insert all imported offset groups in the corresponding offset group containers under the scope of

1_MotherShip. For example, the imported stem offsetgroup can be contained like Fig 5.

Fig 5 : Insert imported offset groups in the offset group container

Insert parameters of mothership

Parameters Values (m) Description

B 58 Beam

Bhalf 29 Half beam

Draft_Design 20.3 Design Draft

Draft_HydroStatic 20.3 Draft for hydrostatic calculation

Propeller_Gap 1.5 Distance between propeller and boss tip

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Rb 2.7 Round bilge radius

xBossTail 7.2701 X position of boss tip

xBulbBeak 328.085 X position of bulb tip

xDeckAftSho 70.2442 X position of after deck shoulder

xDeckBeak 323.498 X position of deck peak

xDwlAftSho 87.4 X position of aft dwl shoulder

xDwlForeSho 268 X position of fore dwl shoulder

xFp 320 X position of fore perpendicular

xParBeg 130.3921 X position of beginning of parallel midbody

xParEnd 238.502 X position of end of parallel midbody

xSternValley 10.4088 X position of stern valley

xTransom -5.5 X position of transom

zBulbBeak 10.4048 Z position of bulb tip

zDeck 28 Z position of deck

zShaft 5.8 Z position of center of shaft

zSternValley 10.6635 Z position of stern valley

There are parameter values detected or calculated directly by offset groups.

Parameters Values Description

Cb 0.8042 Cb value calculated from the imported offset groups

Lcb 0.0356 Lcb value calculated from the imported offset groups

xPropeller 5.7701 xBossTail – Propeller_Gap

zTransom 18.799 Transom height extracted from the offsetgroup sternOH

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5 SETTING DESIGN PARAMETERS

5.1 1_main

Parameters Values (Default) Description

Lack_CbLcbYesNo 0 Cb and Lcb fitting with Lackenby Variation

Station_span 16 Target_Lbp / 20

Target_Beam 58

Target_Cb 0.80424627

Target_DeckHeight 28

Target_DesignDraft 20.3

Target_Lbp 320

Target_Lcb 0.035586

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5.2 2_Propeller_boss

Parameters Values (Default) Description

Boss_Dx 0 X direction displacement of boss tip

Boss_Dz 0 Z direction displacement of boss tip

Boss_HoleDia 1.5 Diameter of boss hole (applied when Boss_Hole_YesNo is

1)

Boss_Hole_YesNo 0 0 : Boss_HoleDia is not applied. Otherwise applied.

Propeller_Diameter 10.1

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5.3 3_Transom

Parameters Values (Default) Description

Transom_Dz 0 Z direction displacement of transom

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5.4 4_fbdy

fbdyFob : Variation of forbody bottom width around Fob region

Parameters Values (Default) Description

dyFobFbdy 0 Maximum Y direction displacement

Mf_x_ymax 0.3 X position of dyForeFobMax in the region

xEnd xFp*0.97 = 310.4 X end of the region

xStart xFp*0.85 = 272 X start of the region

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fbdyShift : X direction shift including forward parallel midbody position.

Parameters Values (Default) Description

dxParEnd 0 X direction displacement of Fwd. Parallel midbody

fbdySectShift_TAE 0 Tangent at end of shift function

fbdySectShift_TAS 0 Tangent at start of shift function

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fbdySide : Y direction variation of section

Parameters Values (Default) Description

dySideFbdy 0 Maximum dy value for frame variation.

Mf_awd_z 0.3 Multiplying Factor to After Height of func_DyContour

Mf_fwd_z 0.6 Multiplying Factor to fore Height of func_DyContour

Mf_x_ymax 0.8 Multiplying factor to X position of DyMax

xstart xFp*0.85 X start of the region

zTop Target_DesignDraft Z boundary

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fvfix : Variation for forebody volume fixing

Parameters Values (Default) Description

isFVF 0 0 : Not applied, 1 : Applied.

Mf_dxFVF 0.75 Multiply factor for controling volume distribution in x

direction.

xFVFEnd Target_Lbp X end of the region

xFVFStart Station_span*15 X start of the region

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5.5 5_abdy

abdyFob : Variation of aftbody bottom width around Fob region

Parameters Values (Default) Description

dyFobAbdy 0 Maximum Y direction displacement

Mf_x_ymax 0.7 X position of dyFobMax in the region

xEnd xDeckAftSho+(xParBeg-

xDeckAftSho)*0.5

X end of the region

xStart xSternValley*2 X start of the region

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abdyShift : X direction shift including aftward parallel midbody position.

Parameters Values (Default) Description

dxParBeg 0 X direction displacement of Awd. Parallel midbody

abdySectShift_TAE 0 Tangent at end of shift function

abdySectShift_TAS 0 Tangent at start of shift function

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abdySkeg : Y direction variation of sections with skeg

Parameters Values (Default) Description

dySkeg 0 Maximum dy value for skeg frame variation

Mf_pivot_fwd_z 1 Z position of pivot at xEnd

Mf_x_ymax 0.4 Multiplying factor to x position for maximum dy

xEnd xSternValley*3

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avfix : Variation for aftbody volume fixing

Parameters Values (Default) Description

isAVF 0 0 : Not applied, 1 : Applied.

Mf_dxAVF 0.35 Multiplying factor for controlling volume distribution in x

direction.

xAVFEnd Station_span*5 X end of the region

xAVFStart xSternValley X start of the region

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5.6 6_Bulb

Parameters Values (Default) Description

dyBulb 0 Maximum dy value for bulb frame variation

dlBulb 0 Bulb length variation

dzBulbTip 0 Bulb tip height variation

dzBulbElev 0 Whole bulb height elevation

Mf_xForYMax1 0.7 Multiplying factor to the first x position for dyBulb

Mf_xForYMax2 0.75 Multiplying factor to the second x position for dy Bulb.

uppProfStartFactor 0.2 Cutting position of upper profile of bulb

xBulbStart Station_span*18.5 X start of the region

zStartDivi Target_DesignDraft*0.6 Z position for dividing upper part at x start

zStartMid Target_DesignDraft*0.2 Z position of dyBulb contour at x start

zStartTop Target_DesignDraft*1.03 Z position of top at x start

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5.7 7_BilgeRadius

Parameters Values (Default) Description

Rb_newValue 0 New bilge radius

Mf_Xstart 0.2 Multiplying factor to xParBeg for x start of the region

Mf_Xend 0.95 Multiplying factor to xFp for x end of the region

Rb_YesNo 0 0 : Not applied, 1 : Applied

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6 HYDROSTATICS VISUALIZATION

Example

Forebody design variables Aftbody design Variables

dlBulb -1 m

dyBulb -3 m

dzBulbElev -1 m

Propeller_Dia 11 m

bossDz 0.25 m

transomDz -0.5 m

dyFobAbdy -2m

dySkeg 1.5m

Forebody and aftbody volume is fixed, i.e. the value of isFVF and isAVF is 1.

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7 STL EXPORT

For exporting STL file, follow the procedure below.

Open the scope 4_Export_STL.

Select the image trimesh bossHole.

Select console command line.

Type

o .exportSTARCCMSTL(“bossHole.stl”)

Enter

Do same way for other trimeshes of deck, hull and transom.

The exported files located in the folder below.

Working Directory … /manual_result/baseline/input

In order to reference the command for export

Type ‘export’ in the console.

Type Ctl + Space.

All commands with the prefix ‘export’ pops up on the console box.