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[ICEM] Non Manifold Boundary

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Old   July 27, 2009, 07:36
Default Non Manifold Boundary
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Ben
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Does any one know what this error is?

A minor internal error has occurred.
You may continue to work but if problems arise they may be related to this error.
Try using the check/fix function to fix the problem
The following message was designed to aid developers fix the problem:

non-manifold boundary at node 2081

any help would be great, I am creating a structured mesh using ICEM for a fully appended sub marine hull form, and i get this error when i try to create the boundary layer around the sub.

any help would be great

Ben
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Old   July 28, 2009, 09:56
Default Non-manifold
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A manifold node is a node with a ring of elements around it... (think a surface node with 8 nodes around it.)

A non-manifold node is a node with more than one ring of nodes around it. This can happen when you pinch two surfaces together. At the point where they touch, there is a ring of nodes on each of the surfaces that touch at that point. Other interesting combinations are also possible.

It signals blocking that is inproperly connected or folded back onto its self, usually due to merge verts...
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Old   May 26, 2010, 05:30
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Hi, I am having a similar problem to Ben. I have created a block then mirrored the block about an axis which runs through one of the vertices. When I try to create an ogrid in either of these blocks I get the same non manifold boundary message as Ben. I attempted to split the vertice to solve the problem but it will not allow me to do so. I had the same problem when taking a top down approach to mesh the same geometry (2D planar).

Any help would be appreciated.

Neil
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Old   May 26, 2010, 05:58
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Problem solved! My geometry has been extruded a very small amount (necessary to run a seemingly "2D" simulation in CFX). The problem arising from the non-manifold boundary was due to a vertice which had been associated with the opposite surface however all vertices appeared to be on the same plane because of the scale of the extrusion (0.01 mm).

Thanks for the post Simon, the problem dawned on me because of it.

Neil
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Old   May 27, 2010, 09:57
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Unfortunately I spoke too soon regarding a solution to the problem. I encountered the same error later on at a different section of the geometry and all vertices were on the same plane. The only solution I found was deleting all blocks surrounding that vertice and attempting to reblock from different approaches. Eventually it worked but for no discernible reason. Further insight would be appreciated.

Neil
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Old   May 27, 2010, 14:51
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That was a minor error... Probably not worth worrying about. Did it stop the mesh from generating? Did the elements look bad? If you want to send me your files, I can help you debug.
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Old   May 28, 2010, 09:35
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It didn't stop me from creating a mesh , however, it was preventing me from creating an Ogrid which I required in order to properly capture the boundary layer. As I did not assign mesh parameters until I had the blocks created, I couldn't fully determine the effect it had on the elements.
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Old   March 31, 2012, 03:52
Default manifold node
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I have a similar problem to this.

The geometry is illustrated in the attachment : the two bodies have different material propeties and heat source, so they must be seperated to two meterial point. But when I O-grid the blocks , the manifold occured.
Attached Images
File Type: jpg halfsphere23.jpg (43.9 KB, 12 views)
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Old   March 31, 2012, 10:59
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XJTH... Sorry I don't understand what "occurred".

As for blocking materials, you must actually assign the blocks to the materials. It is an interactive step, not merely a flood fill.

To do so, right click on the body you want to add blocks to, change the option to blocking material and then select the blocks... Apply...

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