AQWA Stuff

Discussion in 'Software' started by CWTeebs, Oct 13, 2011.

  1. CWTeebs
    Joined: Apr 2011
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    CWTeebs AnomalyGenerator

    I saw a number of people struggling with AQWA and decided to start a thread to generate ideas, post projects and solve problems.

    I forgot what this one was called exactly, so I just called it a 'Knuckle' WEC (Wave Energy Converter). The idea is that there would be a genset doing PTO or pumping fluid to shore for shoreside power. I created the simple geometry in Rhino3D, exported as an IGS, imported into ANSYS Design Modeler, fixed a few of the surfaces (so that normals point outwards). Then I created a Hydrodynamic Diffraction project (AQWA), ran the linear frequency domain calculations required by all subsequent analyses. I then edited a time domain analysis to add hinge connections with a specified stiffness to create the effect you see in the movie.

    I posted a movie on YouTube here:

    http://www.youtube.com/watch?v=pLZFx7l7c9U
     

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  2. CWTeebs
    Joined: Apr 2011
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    Location: Maine

    CWTeebs AnomalyGenerator

    (Disclaimer: my next upload will be of an actual ship, I promise).

    This next simulation is an 'Oyster' SurgeWEC made by a company called Aquamarine. I didn't have exact specifications, so any resemblance to the real video is merely coincidental.

    The first screenshot is the design I tried to replicate. The second is the model I made in Rhino, it only has the first two sections (a single intermediate strut). The third is the geometry after I've meshed it in ANSYS (I ended up removing the middle strut).

    The first link is the result in AQWA in a regular wave, and the second is a real video of an Oyster.

    http://www.youtube.com/watch?v=O2SnqpGdBdI

    http://www.youtube.com/watch?v=S4O0JcNfTKo
     

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  3. gowest
    Joined: Nov 2011
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    gowest New Member

    Hi CWTeebs,

    Nice Work! trying to learn wamit, is it possible to export from solidworks to AQWA ?

    The 'Knuckle' WEC is called McCabe Wave Pump, not far from where me.
    http://www.youtube.com/watch?v=ZyvrTNYMbOY
     
  4. CWTeebs
    Joined: Apr 2011
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    Location: Maine

    CWTeebs AnomalyGenerator

    Gowest,

    Thanks for the information on the McCabe pump, I've updated the video description. To be honest, I simulated it because I saw it in an ANSYS product brochure, lol.

    I said my next video would be a ship, but, I lied. I have it, I just have to take a screen capture of it, lol. Instead I've uploaded a video of an oscillating water column wave energy converter with internal pressure chamber. The actual height of water and body pressures can be extracted in more detail using the subprogram AQWA-FLOW.

    http://www.youtube.com/watch?v=yaml8G10tQo&feature=player_embedded
     
  5. bbinzaghi
    Joined: Dec 2011
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    bbinzaghi New Member

    Hi CWTeebs,

    Thanks for your video. I am currently focusing on wave surface and extremely concerned with 2nd order terms. So, I want to use AQWA-FLOW to generate or output some relevant results which has been calculated by AQWA-LINE.

    Could you let me know where is AQWA-FLOW.exe because can not find AQWA-FLOW.exe existing in my installation dictionary. My ansys version is 12.

    Highly appreciate :)
     
  6. CWTeebs
    Joined: Apr 2011
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    CWTeebs AnomalyGenerator

    On my system it's located at:
    C:\Program Files\ANSYS Inc\v130\aqwa\bin\winx64\AqwaFlow.exe

    That's 64bit version 13 though

    To use AQWA-FLOW you must have included the LDOP option in the previous AQWA-LINE run. Otherwise the actual syntax for running AQWA-FLOW is pretty straightforward, just include a text file of locations in the fluid domain where you want the pressures and fluid velocity components evaluated. I can't remember how it handles points that are identically *on* the hull, e.g. in old aerospace codes to calculate velocities exactly on an airfoil the potential locations are moved slightly in the normal direction, then evaluated, but I'm not sure how AQWA-FLOW handles that.

    You can e-mail me at cthibault@mainemarinecomposites.com
     
  7. Nabeelarslan
    Joined: Jan 2012
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    Nabeelarslan Nabeel

    hi all
    my first post here hope to get solution to my problem

    I m beginner in ANSYS AQWA. I perform analysis on some simple structures like cylinders and a 10x4x2 m. but now i m moving towards a little complex structures having triangular face both sides. in the above mentioned simple structures the meshing was uniform and no triangular elements were generated but with the structure i mention later the meshing produces triangular and of variable sizes. when i solve the above mention structure following errors are encounter.
    1)elements must be at least 1.000x Facet radius apart.
    2)The ratio of the areas of adjacent elements must be less than 0.333

    If any body could help me. I''l be sincerely thankful to that persons

    Regards

    Nabeel
     
  8. Nabeelarslan
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    Nabeelarslan Nabeel

    I am using workbench hydrodynamic diffraction approach.
     
  9. CWTeebs
    Joined: Apr 2011
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    CWTeebs AnomalyGenerator

    You need to adjust the maximum element size and defeaturing tolerance when meshing. You may also need to enable the 'GOON' (for Go On) option (but remember to check the mesh quality, as a rule of thumb you don't want more than 10% of the panels that comprise the mesh to fail the mesh metrics).
     
  10. Nabeelarslan
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    Nabeelarslan Nabeel

    thanks for the reply

    i used different element sizes and defeaturing tolerance and kept the ratio of the the to about .6 as mentioned int the aqwa help.as i m using workbench hydrodynamic approach so cannot use the GOON option there :(

    i have no control of meshing in aqwa workbench. if u could tell me some technique to control meshing in aqwa workbench.

    another thing which i tried today is created mesh in ansys APDL to have a better mesh quality (i created a very good mesh which i consider an ideal mesh for structural analysis) and generated its aqwa file using "anstoaqwa" command and then converted it to DAT file and opened it in aqwags but it again gave the same errors :(

    i have no clue what to do because i have no instructor with me :(
    if u could upload a video on youtube analyzing a ship in aqwa for some RAO, hydrostatic analysis and a pressure and motion contour :)
    I'll be so much obliged by ur help.

    Regards
    Nabeel
     
  11. CWTeebs
    Joined: Apr 2011
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    Location: Maine

    CWTeebs AnomalyGenerator

    >> as i m using workbench hydrodynamic approach so cannot use the GOON option there

    Actually, setting the Workbench option "Ignore Modeling Rule Violations" to "Yes" inserts the GOON option behind the scenes (in the AQWA-LINE job file that gets generated). In the case of the mesh metrics, these are really just suggestions, e.g., WAMIT doesn't even check the mesh quality. In many instances, you can have a number of panels that aren't ideal, so long as most of them are okay, but this is more of an art, not a science. When you do this, you must check for the message that says "X modeling rule violations ignored" where X will be the number of panels that fail the mesh metrics. Again, as a rule of thumb, if X is less than 10% of the total number of panels, this is probably okay, but you want to get it as low as possible. For a number of experimental devices with weird geometries, it's often impossible to get a perfect mesh.

    >> i have no control of meshing in aqwa workbench. if u could tell me some technique to control meshing in aqwa workbench.

    Yes you do, you can directly manipulate the maximum element size, defeaturing tolerance, local element size to a particular region of your mesh, and the mesh method.

    >> i have no clue what to do because i have no instructor with me
    if u could upload a video on youtube analyzing a ship in aqwa for some RAO, hydrostatic analysis and a pressure and motion contour

    I've been really busy lately, but, I've been planning on doing just that. Right now, I'm working to secure rights to experimental tank tests that I can use to replicate in AQWA, for the purpose of marketing my abilities in AQWA. There's been a TON of people asking for help.
     
  12. Nabeelarslan
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    Nabeelarslan Nabeel

    Thanks again for your help

    It was really helpful for me and at least I am able to preform an analysis for a little complex model.

    I am feeling a bit awkward within my self that I keep on putting more questions to u, but I think it will continue as long as I attain reasonable skills or you are fed up of me :)

    The thing I want to ask is that as I mentioned in my last post that i used a DAT file in AQWAGS.The problem I face now is that it contained only nodal and elemental information and has no information regarding material properties like mass, moment of inertia and frequencies.I have figured out a bit how to write information in the DAT file Manually but i want to give all this information in the AQWAGS interface.I tried to do so and it accepted the frequency values but was not respondent to the mass or moment of inertia inputs.I need some help regarding this.

    Hope you'll not mind my repeated questions :)

    Regards
    Nabeel
     
  13. Nabeelarslan
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    Nabeelarslan Nabeel

    Hi Friend,

    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 you tell me the procedure to transfer the data obtained from the analysis to ansys aqwa wave or asas?

    Regards
    Nabeel
     
  14. CWTeebs
    Joined: Apr 2011
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    Location: Maine

    CWTeebs AnomalyGenerator

    Attached Files:


  15. CWTeebs
    Joined: Apr 2011
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    Location: Maine

    CWTeebs AnomalyGenerator

    I'm sorry, I completely missed your original question. ANSYS is trying to incorporate this into Workbench, but, I've got a tutorial that explains how to export the stress range transfer function for FEA analysis, I'll see if I can get an electronic copy.

    EDIT:
    Are you the person that was e-mailing me about solving hydroelastic problems with FEA <-> AQWA communication?
     
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