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[ANSYS Meshing] Volume Orientation Problem

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Old   November 9, 2012, 09:55
Default Volume Orientation Problem
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Kentin cal
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Hello everybody!

Here is my problem :
pier.jpg

As you can see on this picture, it shows a draft tube pier. I use o-grid and an hexa meshing.
After an ICEM checkMesh, it informs me that negative volume are present on this part. I tried many stuff to fix the problem but it unfortunately did not come off.

I wil be very glad to have some help,

Kentin
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Old   November 9, 2012, 11:12
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what do you mean by negative orientation? is it negative quality?

Negative orientation : Blocking > Edit Block > Change Block IJK

Negative quality : Improve blocking
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Old   November 9, 2012, 11:32
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Negative volumes are defined when i do a Blocking->Pre-Mesh Quality (criterion determinant 3*3) between -1;1.
I find volumes below 0 with this criteria, concentrated on pier nose (see picture in my first post).

Once again, i find these volumes when i do a checkMesh with option createSubset. I Volume Orientation Subset is created and means that i have an error here. I tried to unrefine mesh and other things but i did not find solutions to solve this volume orientation problem.

If you have any idea...
Thanks a lot,

Kentin
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Old   November 9, 2012, 18:45
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make sure edge bunching law all same for all parallel edges.
Use scan edge to see where does the problem come.
You may share your project, i can take a look at it...
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Old   November 12, 2012, 10:53
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I checked all parallel edges and did not find anything special.
Same thing for scan planes, actually first picture i posted came from a scan. And as you can see, there is no special thing visible..
If you have any others ideas to check meshing, i ll be very glad to hear it!

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Old   November 12, 2012, 11:31
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sometime for a simple update of the pre-mesh can help solve the problem. Would you mind sharing your project. i can take a look at it. Thanks
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Old   November 13, 2012, 06:01
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in my mind, if you have some negative volumes, maybe you have some problem association ,you shoud see the edge association
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Old   November 13, 2012, 13:09
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Thanks but i finally found the solution.

In blocking->check Blocks->Fix Inverted Blocks, very usefull tool! No negative volume anymore.

Thanks for all your advices.

Kentin
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Old   November 13, 2012, 13:31
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Quote:
Originally Posted by Far View Post
what do you mean by negative orientation? is it negative quality?

Negative orientation : Blocking > Edit Block > Change Block IJK

Negative quality : Improve blocking
Are u talking about change block IJK?
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Old   November 14, 2012, 04:01
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Negative orientation is not negative quality but negative volume specified by 3*3 determinant quality.
I found the solution thanks to this post :
How to fix negative volume elements in icem cfd?
I just used the tool i notice in my last post..
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