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Old   January 6, 2012, 02:51
Unhappy Skewed elements on KVLCC2 hull
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Terence Chung
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Hi everyone. I'm meshing a ship hull on Gambit and having skewed elements on 6 faces of the hull. I have applied a curvature sizing function on the hull side and have tried various ways(eg. refining the curvature sizing function, splitted the faces with skewed elements) but they do not work so far. I have the screenshot of the mesh here. Suggestions/ reasons would be most welcome.

Thank you in advance!

Terence
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Last edited by s7evin; January 6, 2012 at 03:59.
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Old   January 6, 2012, 05:41
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Maxime Perelli
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try to reduce the max size (in size function panel)
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Old   January 6, 2012, 13:21
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Just try to mesh different volumes differently with smaller mesh size.
And try to use use different schemes in areas where skewness is high.
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Old   January 10, 2012, 03:09
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Thanks mAx and shk12345! Reducing the max size for size function works!
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Old   January 16, 2012, 13:16
Default ACIS error 8032 and ACIS error 30001 encountered for KVLCC ship hull
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I have another problem here. I'm trying to create the flow volume by subtracting the ship hull from a brick and the flow volume is multiphase, the top for the air and bottom one for water. I have persistently encountered the following errors:
1. ERROR: ACIS error 8032: inconsistent edge-face relationship
2. ERROR: ACIS error 30001: coincident face_face_ints with different body vertices.

I have done the volume checks and there are no errors detected. Funnily enough, I didn't encounter this problems when I did a scaled up version of the exact same model. Sorry for the numerous questions, I am very new to Gambit. I can also send the .dbs if you think you want to have a closer look.

Suggestions/ reasons are very welcome! Thanks!
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Old   January 17, 2012, 02:16
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Maxime Perelli
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substracting will only work, if you do it with 2 volumes, or 2 surfaces.
But not with a volume and a surface.
In your case, your need to split your volume, with the surface.
Once your split is done, you can do your other split for multiphase.
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Old   January 17, 2012, 04:14
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Yeah, all were in volume form when I attempted the subtraction. I have already split the volume with surface as well. Could there be other reasons?
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Old   January 17, 2012, 04:21
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hull volume should be fully in your outer volume (not just one half for instance), and both volume should be real
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Old   January 17, 2012, 09:04
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hi
just try to make the two volume geometry in some cad model as gambit is too old now.
then import in gambit and do meshing and bc there and then import in fluent.
means make two real volume one your ship hull as a single volume and then make the outer two boxes and then substract them when they are 2 volumes.
Or try to do that in gambit whatever suits you.


Hope that will help you
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Old   January 17, 2012, 13:49
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Hi max, the hull volume is fully in their outer volumes and I have aligned to ensure it is as such. Also both volumes are real. I still could not subtract to obtain the flow volume.

Hi shk12345, what cad model do you recommend? I have tried to do it on Solidworks but there was so much cleanup to be done that it was more economical to do it on gambit.

Many thanks for your patience!
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Old   January 17, 2012, 13:51
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Quote:
Originally Posted by s7evin View Post
Hi max, the hull volume is fully in their outer volumes and I have aligned to ensure it is as such. Also both volumes are real. I still could not subtract to obtain the flow volume.

Hi shk12345, what cad model do you recommend? I have tried to do it on Solidworks but there was so much cleanup to be done that it was more economical to do it on gambit.

Many thanks for your patience!
try to make the solid ship hulk in solid works and make the outer portion in ansys workbench
i hope that will make the work easier

regards
shk
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Old   January 18, 2012, 08:37
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ok I checked your geometry (half).
You have a problem at edges 1-2-6-143-12
You may fix this issue.
But I tried on the full geometry, and it is ok if you unite first both outer domains, and if you have only one hull volume. For that unite doesn t work, and you need to delete both hull volumes (lower geometry disabled). Then delete the common surface (face.81), and recreate volume from all hull surfaces.
Then substract is ok.
But attempting to split on the middle will fail.
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Old   January 18, 2012, 12:15
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Pardon my ignorance, but do I have to keep the flow volume split for multiphase?
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Old   January 19, 2012, 02:07
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Yes you can, but you should do the split, after substract is successful
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Old   January 28, 2012, 10:38
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Thank you for the advice mAx!
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