Mesh creation in ANSYS AQWA for Sea Keeping Analysis

[Alvarocotaquisp]

Originally Posted by CWTeebs

I realize this thread is old now, but, I've been using AQWA for the past few months, and, now that I'm actually GOOD at it I'm interested in helping others get started, as a hobby. It's a sophisticated program but extremely difficult to use.

Anyway, if anybody wants help, email cthibault@mainemarinecomposites.com



Again, I realize that this is all very old topics, but there's also not much of an AQWA user community out there that I've found, but I've found that for all but the simplest shapes (cylinders, box barges), it's impossible to satisfy all of the meshing criteria. This is okay in most cases as the simple shapes are pretty good indicators of wave loadings. The 'GOON' option also doesn't really constitute true 'errors', they are really warnings about the geometry as the relative size of the panels can cause the calculated element strengths to be erroneous.

I'm messing around with Excel's optimizer in VBA to jiggle the points to satisfy the mesh on a per-body basis.

How CWTeebs. im Alvaro. Im ship's engineer studient from unversity from Peru. Here we are using the ansys ICEM CFD to calculate the resistance to advance of a ship and compare ours results with experimental tests (tow test) (this estudy was presented in a conference in other countrie). but now i want learn to use the AQWA to can make studies about breakwater to my investigation project. Your help will be very very useful here because in our country, our university is the unique that has this major and we dont have many facilties to develop our major. we are using RHINOCEROS, MAXSURF, AUTOSHIP, we want learn AVEVA MARINE too but it's very expensive to have the license. we know something about POSEIDON and SHIPCONSTRUCTOR too but cant develop them because we dont have the license. well i hope that you can help me. i'll thank you to much. good bye!!!!

[Alvarocotaquisp]

Hi friend im new in this. id like to learn more about the AQWA and ASAS to my project will be great if you can send to me some tutorials o AQWA.

my msn is alvarocotaquispe@gmail.com ...thanks

[Alvarocotaquisp]

im Alvaro. Im ship's engineer studient from unversity from Peru. Here we are using the ansys ICEM CFD to calculate the resistance to advance of a ship and compare ours results with experimental tests (tow test) (this estudy was presented in a conference in other countrie). but now i want learn to use the AQWA to can make studies about breakwater to my investigation project. Your help will be very very useful here because in our country, our university is the unique that has this major and we dont have many facilties to develop our major. we are using RHINOCEROS, MAXSURF, AUTOSHIP, we want learn AVEVA MARINE too but it's very expensive to have the license. we know something about POSEIDON and SHIPCONSTRUCTOR too but cant develop them because we dont have the license. well i hope that you can help me. i'll thank you to much. good bye!!!! MY MSN is alvarocotaquispe@gmail.com

[Nabeelarslan]

Hi Friends,

I performed an analysis in aqwa workbench on a hull and found the pressure due to wave loadings.Now I want to transfer this data to aqwa wave or asas for structural analysis under his wave loading.Can anywone tell me the procedure to transfer the data obtained from the analysis to ansys aqwa wave or asas?

Regards
Nabeel

[JannesH]

Good Afternoon Nabeel,
since I am woking on a projekt with exactly the same target, it would be nice to get in
touch. I am doing projekt work at IIT-M Feel free to contact me:JannesH@gmx.de
Unfortunately I am not yet be able to help u cuz I started a couple of days ago.

Best Regards

Jannes

[Nabeelarslan]

Good Afternoon Jannesh

Its great to know that you are also working on the same project.I'll keep in touch with you regarding my working.You may please also keep me informed.

Regards
Nabeel

[wgingenieria]

Hola Alvaro, usa los archivos solo para tus estudios, no los distribuyas por la red. Espero te sirvan

Originally Posted by Alvarocotaquisp

Hi friend im new in this. id like to learn more about the AQWA and ASAS to my project will be great if you can send to me some tutorials o AQWA.

my msn is alvarocotaquispe@gmail.com ...thanks

[CWTeebs]

Just curious, where is the last pdf, "AQWA-Tutorials" from? Is that something you generated?

- CWTeebs

[Nabeelarslan]

http://wenku.baidu.com/view/1692acd9...ght=36&count=5

Check this link out. Hope you may get some useful data from here. Also see other files at this link.

Nabeel

[JannesH]

Hey Nabeelarslan,
how is your project going so far. Did you find a good way of transferring the pressure contour from aqwa into mechanical?
After a long period of model generation for aqwa itself due to a kind of cmplex
hull shape i finally reached the point you got stuck a while ago.
In order to avoid any difficulties due that complex shape I went back to a simple box shape in order to prove the way. After generating another model for ASAS using an mechanical macro and writing an .dat file for wave I face a simple problem. The Manul refers to the fact that for exportation of the pressure values an LOAD case 1000 in ASAS has to exist. Since I don"t have that my generated .dat File for import into mechanical shows no element loads.Only the COG and Accel. is included. The run of WAVE shows no errors, but in in the .out file I am missing a proper LINK to the asas model. How did you generate the LOAD Case 1000 in ASAS. If you like I can also send you the dat file for checking... Thanks for your help
Best regards from Chennai
Jannes

[Nabeelarslan]

Well Jannesh before creating ASAS file from ANSYS apply unit load(pressure) on all the diffracting elements, it will generate load case 1000 in the ASAS file. before meshing the model cut it at water line so that dafracting and non-diffracting elements are separated.
Do tell me whether it worked or not.
Regards
Nabeel

[JannesH]

Dear Nabeelarslan,

Thank you very much for your reply.
I did as you said as follows, by using WOrkbench Ansys Structural.
Loaded the Geometrie into the Modul, same Geomterie I used for the AQWQ LINE run,
splitted at waterline etc.
I used the inbuild mesh function to with a max mesh size of 5m.(my box is 30x30x30 with water
leverl at 7.5m)
I apllied to each surfcace wich should be diffracting
a static pressure load of 100 Pa.
I inserted into the solution tree a Commands APDL "anstosas,box,0"
This File consists now a LOAD CASE 1000 as you promised. but unfortuantely it
also consits Elements of FLA2. which cause some trouble running AQWA Wave in the end.

I am facing following Erros:
I.

CROSS CHECKS ON ELEMENT, MATERIAL, GEOMETRY, AND SKEW DATA
----------------------------------------------------------

*** ERROR *** MATERIAL NUMBERS MISSING
9
10
AQWAWAVE 12.01.00.0 ( ) 12:40 24-04-2012


[Don't know where this is comming from, since I choose the material in the Geometrie
and the QUS4 Elements have Material 8 which is causing no problem]


II.

NO. OF EACH ELEMENT TYPE IN JOB
-------------------------------

ELEMENT TYPE NUMBER OF ELEMENTS
------------ ------------------


FLA2 48
QUS4 4560



*** ERROR *** MATERIAL 9 REFERENCED ON ELEMENT 6435 IS NOT DEFINED
*** ERROR *** MATERIAL 9 REFERENCED ON ELEMENT 6434 IS NOT DEFINED
*** ERROR *** MATERIAL 9 REFERENCED ON ELEMENT 6433 IS NOT DEFINED
*** ERROR *** MATERIAL 9 REFERENCED ON ELEMENT 6423 IS NOT DEFINED
*** ERROR *** MATERIAL 9 REFERENCED ON ELEMENT 6422 IS NOT DEFINED


[this goes on]

I have the impression that this is a result of some fundamental mistake I am making
maybe due to meshing?


III.

CREATING COMPONENT TREE
-----------------------


BUILDING STRUCTURE ANSY ON PROJECT ANSY

ERRORS HAVE OCCURRED WHILST READING THE ASAS DATA FILES

[Of course this is the result of the whole mess]

Hopefully you can help me out one more time.
Are you usign workbench as well?

[JannesH]

Dear Nabeelarslan,

I figured out the problem of the FLA2 elements and their not existing material property.
I didn't bother much about the boundary conditions while exporting the model since it was
only about the geomtrie and the mesh. Well this is where I made a mistake.

That's why weak springs were automatically added by the software.
Those were concerted into FLA2 Elements while using the anstoasas macro.
I defined a fixed support to restrict motions and now those elements are not shown
anymore. AQWA WAVE runs without any Errors and now the box_aqld1001.dat shows as follows


/TITLE, CASE 1001 'H = 2.0 T = 20.0 D =-180.0 P = 0.0'
! COMPONENT ANSY
SFEDELE,ALL,ALL,PRES
FDELE,ALL
LSCLEAR,INER
SFE, 1, 2,PRES,0, -5.7482E+02, -3.3539E+02, -3.0726E+02, -5.4465E+02
SFE, 2, 2,PRES,0, -5.4465E+02, -7.6705E+02, -7.9372E+02, -5.7482E+02
SFE, 3, 2,PRES,0, -3.0726E+02, -2.9148E+02, -5.3071E+02, -5.4465E+02
SFE, 4, 2,PRES,0, -5.3071E+02, -7.5148E+02, -7.6705E+02, -5.4465E+02
SFE, 5, 2,PRES,0, -2.9148E+02, -2.8648E+02, -5.2659E+02, -5.3071E+02
SFE, 6, 2,PRES,0, -5.2659E+02, -7.4637E+02, -7.5148E+02, -5.3071E+02
SFE, 7, 2,PRES,0, -2.8648E+02, -2.9204E+02, -5.2966E+02, -5.2659E+02
SFE, 8, 2,PRES,0, -5.2966E+02, -7.5148E+02, -7.4637E+02, -5.2659E+02
SFE, 9, 2,PRES,0, -2.9204E+02, -3.0964E+02, -5.4802E+02, -5.2966E+02


....[this goes on]


No I am only facing a small problem about how to input that DATA properly into the
Mechanical Workbench Project Tree.

I added a Commands (APDL) in the Solution Section and insertet the generated Input
Information

!TITLE, CASE 1001 'H = 2.0 T = 20.0 D =-180.0 P = 0.0'
! COMPONENT ANSY
/INPUT,box_aqld1001.dat

Somehow int doesn't show any normal stresses due pressure. It only reacts on the
Acceleration Information at the end of the box_aqld1001.dat File

ACEL, 1.7022E-07, -8.1131E-07, -9.9184E-02
CGLOC, 1.5000E+01, 1.5000E+01, 0.0000E+00
DCGOMG, 1.3688E-06, -3.4701E-07, 2.1454E-08

So basicly my box is hanging from fixed at the top and therefore the bottom
shows some deformation.

Do you mind telling me, how you inserted your results?

Best regards

Jannes

[JannesH]

Dear Nabeelarslan,

meanwhile I could solve my problems and the import of DATA works fine.
The problem which occured earlier was caused by the size of the box.
The reaction due to gravity were just several times bigger than due to hydrodynamic forces. So it was just out of sight.
I still have problems with plotting only the SFE in Workbench. All the information regarding that are based on ANSYS classic.
Well this is a minor thing.
Now my vessel is floating well balanced in an acceleration filed under inertia relief option and reacts according to the hydrodynamic forces.
Main bahut kush hoon!
Since you seem to be very experienced with AQWA I d like to ask a question about the RAO in AQWA. If I decrease the time step of my calculated of my calculated frequencies, the solution seems increase. Maybe a problem with convergence. Any Idea how to deal with that in AQWA or how to check convergence?

Best regards

Jannes

[UTKARSH RAMAYAN]

Hi Jannesh,
I am working as a research scholar in iit madras on offshore wind turbine in ocean engg depertment.glad to know that u r also working here . i really need some assistance regarding ansys asas software.
I will be really greatful to u if u can provide me some information about this software .
with regards
UTKARSH RAMAYAN