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vk.com/club152685050Applying Ocean Loading from| vka Hydrodynamic.com/id446425943Analysis

12 6.357081E-01 8.999005E+01 6.357080E-01 8.999005E+01 1.042556E+00 4.340762E-02 5.293267E-01 8.999037E+01 5.293267E-01 -9.000961E+01 1.605987E-07 0.000000E+00

18.3.10. Mass Properties

This section defines the mass properties of the hydrodynamic model but is currently unused.

MASS

xcg ycg zcg

Mass(1,1) mass(1,2) .. mass(1,6)

.

.

Mass(6,1) mass(6,2) .. mass(6,6)

where

 

 

 

 

 

MASS

keyword to denote start of mass information

 

xcg ycg zcg

X, Y and Z coordinate of CoG

 

 

 

mass(j,k)

mass matrix term

 

 

 

Example 18.9: Mass Properties

 

 

 

MASS

 

 

 

 

 

0.000000E+00

0.000000E+00

-5.000000E+00

 

 

 

1.383750E+07

0.000000E+00

0.000000E+00

0.000000E+00

0.000000E+00

0.000000E+00

0.000000E+00

1.383750E+07

0.000000E+00

0.000000E+00

0.000000E+00

0.000000E+00

0.000000E+00

0.000000E+00

1.383750E+07

0.000000E+00

0.000000E+00

0.000000E+00

0.000000E+00

0.000000E+00

0.000000E+00

7.780000E+08

0.000000E+00

0.000000E+00

0.000000E+00

0.000000E+00

0.000000E+00

0.000000E+00

7.780000E+08

0.000000E+00

0.000000E+00

0.000000E+00

0.000000E+00

0.000000E+00

0.000000E+00

7.780000E+08

18.4. Example Analysis Using Results from a Hydrodynamic Diffraction Analysis

In this example, a 30m x 30m x 22.5m box with 7.5m above the water level (z = 0m) was modeled in a hydrodynamic diffraction analysis.

The following conditions exist:

The diffracting elements are 3m x 3m.

Waves are defined in eight directions and four frequencies (0.031, 0.5, 0.97, and 1.43 rad/s).

Forward speed and hydrostatic pressures are not included.

The pressure results from the hydrodynamic diffraction analysis are 45°, 1.43 rad / s, t / T = 0, as shown in the following figure:

 

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vk.com/club152685050 | vk.com/id446425943Example Analysis Using Results from a Hydrodynamic Diffraction Analysis

Figure 18.1: Hydrodynamic Diffraction Analysis Pressure Results

An .ahd file named analysis_1, which contains the data from the hydrodynamic diffraction analysis, was generated via the AQWA product's AQWA2NEUT utility, as follows:

aqwa2neut analysis 1

The diffracted wave loading data in the analysis_1.ahd file is imported (OCREAD) and applied to the structural model for further analysis, as shown in the following example input:

/verify,difwaveeg

/FILNAME,difwaveg

/prep7

/TITLE,difwaveeg, EXAMPLE FOR AQWA LOADING

/com **************************************************************************

/com SHELL MODEL OF A HOLLOW BOX TUBE /com CREATED 20/05/10

/com **************************************************************************

antype,static

nlgeom,off

!define shell section sectype,11,shell secdata,0.1

!define ocean matwat=2 idwat=2 idcur=3 idwav=4 depth=250.0

!define geometry /prep7 !wpoff,,,-15

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vk.com/club152685050Applying Ocean Loading from| vka Hydrodynamic.com/id446425943Analysis

k,,-15,-15,-15 k,,15,-15,-15 k,,15,15,-15 k,,-15,15,-15 l,1,2

l,2,3

l,3,4

l,4,1 k,,-15,-15,0 l,1,5 k,,-15,-15,7.5 l,5,6

adrag,1,2,3,4,,,5,6

a,1,2,3,4

!Mesh et,1,181 type,1 mat,1 secnum,11 esize,1 amesh,all et,2,154 keyopt,2,4,1

keyopt,2,8,idwat

r,2

rmore,0.0001

type,2

mat,1

real,2 esurf

!steel material properties MP,EX, 1,2.1e11 MP,PRXY,1,0.3

MP,ALPX,1,0.0

MP,DENS,1,7800.0

!water density mp,dens,matwat,1025.0

!supports

d, 1,ux d, 2,ux d,977,ux d,497,ux d, 1,uy d, 2,uy d,977,uy d,497,uy d, 1,uz d, 2,uz d,977,uz d,497,uz finish

!

/SOLU

!CASE 4 H=1 T=4.384199 PH=0 D=45 acel,0,0,9.8

!ocean

octype,basic,ocean1

ocdata,depth,matwat

!!diffracted wave octype,wave ocdata,8,45.0 octable,1.0,200,0.0

!

!!ocread to read in external data file ocread,analysis_1,ahd

!

! list all slist,all oclist,all

!!apply inertia relief

!!irlf,1

NSUBST,1,1

! 1 SUBSTEPS

 

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vk.com/club152685050 | vk.com/id446425943Example Analysis Using Results from a Hydrodynamic Diffraction Analysis

TIME,1.0

OUTPR,all,1

OUTRES,all,1 solve

finish /post1

etable,x,smisc,13

pletab,x,avg

The following figure shows the analysis results using the pressures from the diffracted wave:

Figure 18.2: Analysis Results Using Pressure Data from a Hydrodynamic Diffraction Analysis

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of ANSYS, Inc. and its subsidiaries and affiliates.