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[ANSYS Meshing] Blade tip blocking

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Old   January 29, 2013, 10:28
Default Blade tip blocking (icem)
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Hi everybody,

I'm meshing a three blade wind turbine and some blocking located at the blade tip are causing me trouble.
In the 1st picture you can see the blade tip with sharp trailing edge and its blocking. There are O-grid blocks around the blade and then all edges converge to a unique vertex in the very extreme of the tip + O-grid distance (vertex 624).
In the message box you can see that a collapsed edge is causing an internal error. This is causing negatives volumes as it is shown in the histogram (negative volumes for the same point of view are shown in the 2nd picture).

How can I avoid that?

Is there a better option for blocking at the blade tip?

Thanks in advance!
Attached Images
File Type: jpg Blade_tip_blocking.jpg (63.3 KB, 154 views)
File Type: jpg Negative_volumes.jpg (97.7 KB, 115 views)

Last edited by Bollonga; January 29, 2013 at 17:58. Reason: Prefix should be ICEM instead of ansys meshing
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Old   January 29, 2013, 11:06
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attach files.
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Old   January 29, 2013, 14:31
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that's not what I would call a sharp trailing edge...
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Old   January 29, 2013, 14:54
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In the picture the visible edge is the leading edge. The trailing one is on the backward side.
Also, it can be confusing because there's a curve of the same colour as the surface.
But I think that's a sharp edge.

Thanks.
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File Type: png Blade_tip_curves.png (11.2 KB, 54 views)
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Old   January 30, 2013, 06:06
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Well, geometry files are not mine so I can't share them until I got permission.

I've realized that negative volumes are not only at the blade tip but in the whole blade surface. I'm gonna try a simpler blocking around the blade and I'll try again.

I'll keep posting.
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Old   January 30, 2013, 06:14
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Like this?















PS: This was not done by me. I guess this master piece was done by Ralen (But I am not sure)
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Last edited by Far; January 30, 2013 at 06:34.
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Old   January 30, 2013, 06:45
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see this post

Problem with meshing half NACA0009 in 3D

For 2nd thought

mesh of a spinnaker
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Old   February 11, 2013, 18:33
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Hi, I'm back with the blade tip blocking after some days off. I've seen Ralen's approach but I have some questions. In the comment #12 of the thread:

Problem with meshing half NACA0009 in 3D

In step 2 and 3 I don't know exactly in which surface I have to do the o-grid. I guess it's in the selected surfaces in the attached picture, if I am right how do I create an outer o-grid in just that selected surfaces? If I enable around selected blocks the o-grid appears all around the blocks, and not just in the selected surfaces.
Attached Images
File Type: png blade_tip_blocking.png (34.8 KB, 44 views)
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Old   February 12, 2013, 05:58
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Quote:
Originally Posted by Bollonga View Post
In step 2 and 3 I don't know exactly in which surface I have to do the o-grid. I guess it's in the selected surfaces in the attached picture, if I am right how do I create an outer o-grid in just that selected surfaces? If I enable around selected blocks the o-grid appears all around the blocks, and not just in the selected surfaces.
I've already solved that, I was just messed up with the o-grid selection.
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Old   February 13, 2013, 11:18
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After several trials I've managed to get some valid blocking for the blade tip following Ralen's approach. See picture 1 before associating vertices
Then I've made all the vertex-point, edge-curve and face-surface associations (picture 2 and 3).
But when I start meshing, there's somethins strange at the tip (see pictures 4 and 5), this has happened to me other times but I don't know how to fix it now. I've checked all associations and they seem all right to me. Why does this happen?
Attached Images
File Type: png Tip blocking.png (31.2 KB, 43 views)
File Type: png tip_edge_association.png (40.9 KB, 24 views)
File Type: png tip_surface_association.png (36.5 KB, 24 views)
File Type: jpg tip_mesh_problem_side_1.jpg (62.5 KB, 31 views)
File Type: png tip_mesh_problem_side2.png (62.9 KB, 34 views)
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Old   February 13, 2013, 11:36
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Quote:
Originally Posted by Bollonga View Post
But when I start meshing, there's somethins strange at the tip (see pictures 4 and 5), this has happened to me other times but I don't know how to fix it now. I've checked all associations and they seem all right to me. Why does this happen?
Solved, I just had to move one of the vertex because it was to close to side1 instead of side2.
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Old   February 13, 2013, 12:14
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Quote:
Originally Posted by Bollonga View Post
Solved, I just had to move one of the vertex because it was to close to side1 instead of side2.
good...................
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Old   February 20, 2013, 05:45
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I've found a new issue. I've been trying to solve it for a while but I can't find a solution.
The problem is that I want to mesh two parallel edges from a rectangular surface, everything pretty simple (purple surface in picture 1). I've done the associations point-vertex, edge-curve and face-surface. I do the bunching (picture 2), copying to all parallel edges, but it's not meshing properly (picture 3). The two long parallel edges are being mesh just from a concentrated point near the corners (pictures 4 y 5).

What is the cause? What can be the solution?

Thanks a lot!

PS: I don't know if I should open a new thread for this matter, as it is no longer related to the balade tip.
Attached Images
File Type: png rectangular_surface.png (43.5 KB, 18 views)
File Type: jpg bunching_corner.jpg (32.6 KB, 12 views)
File Type: png rectangular_surf_meshed.png (36.7 KB, 14 views)
File Type: png vertex_1239.png (10.8 KB, 13 views)
File Type: png vertex_1241.png (15.3 KB, 11 views)
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Old   February 20, 2013, 05:47
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It is the association issue. check associations !
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Old   February 20, 2013, 06:10
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Quote:
Originally Posted by Far View Post
It is the association issue. check associations !
I've checked all associations, even edge to surface ones (picture 1). Everything seem okay. I've done the same for the nearby rectangle and this one has been properly meshed (picture 2).

You think it's a edge to curve association issue of the two long sides?
Attached Images
File Type: png associations_rectangle.png (18.5 KB, 18 views)
File Type: jpg rectangle_ok.jpg (96.4 KB, 26 views)
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Old   February 20, 2013, 06:12
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Yes. It could be edge to curve or vertex to point association problem.
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Old   February 20, 2013, 06:25
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I still don't find the problem. What does the white arrows in previous picture 1 mean? I don't hace those arrows in the other rectangles.
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Old   February 20, 2013, 06:35
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Blocking -> Associate -> Update Association.

If it doesn't work, you would have to redo all the association hand by hand.
Your problem sometimes occures if you delete curves or trim surfaces ... It's always better to disassociate a curve (Blocking -> Associate -> Disassociate from geometry -> Edges), and then reassociate.

Good luck
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Old   February 20, 2013, 06:46
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Quote:
Originally Posted by BrolY View Post
Blocking -> Associate -> Update Association.
That solved the problem! Far, you're the man.
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Old   February 20, 2013, 09:53
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Quote:
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That solved the problem! Far, you're the man.
I meant Alenxadre, merci beaucoup! Thank you too, Far!
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