[ICEM] Check Mesh can't work !

peter.wang · April 21, 2010, 04:59

I have been diagnosing some tetrahedral mesh with ICEM > Edit Mesh > Check Mesh. But I found some terms couldn't work, involving Delaunay-violation, Overlapping elements.
I have presented more detail about my problem in the attachments, including four mesh data file. Please give me a hand, I'm waiting online.

peter.wang · April 23, 2010, 00:03

Why not hand? I'm waiting online!

peter.wang · April 23, 2010, 00:04

Please help me!

PSYMN · June 8, 2010, 19:52

I missed this one, and now you have probably moved on. However, if you still need help with this, let me know.

Simon

peter.wang · June 10, 2010, 02:31

Quote:

Originally Posted by PSYMN

I missed this one, and now you have probably moved on. However, if you still need help with this, let me know.

Simon

Absolutely need! Can you offer some suggestion? Free contact with me via Email sanshi.wang@gmail.com.

PSYMN · June 10, 2010, 13:09

Ok, I just took a quick of your attachment and see that this is just about quality metrics. I am curious about why you were doing this research...

I checked (on my own and fired off an email to development and doc) and see that the doc is correct. Your examples are not. Both of these checks are looking for surface elements (triangles), you have provided volume elements (Tetrahedrals).

So Overlapping elements is not usable because it only works on surface elements (TRI_3 and QUAD_4). It checks for all surface element edges if the any angle of the vector between the centroid of the surface element and the mid point of the element edge projected into the surface element plane and the vector between the centroid of a surface neighbor element and the mid point of the element edge projected into the surface neighbor element plane is less than 5 degrees. If so this will be marked as an overlap. These can cause a problem for delaunay because it is difficult to fit a decent tetra between the overlapping tris.

The Delaunay check is similar. it is meant to be run before delaunay, so it applies to tri elements only (which it says in the first few words of the doc.)

Just a side note; Most Delaunay meshers are now much more robust and failing the delaunay check is no longer a concern. I usually just skip it and focus more on the critical issues of single edges and overlapping elements....

June 8, 2010, 19:52	Still need help?	#4
PSYMN Senior Member Simon Pereira Join Date: Mar 2009 Location: Ann Arbor, MI Posts: 2,663 Blog Entries: 1 Rep Power: 47	I missed this one, and now you have probably moved on. However, if you still need help with this, let me know. Simon

June 10, 2010, 13:09	Checks for Surface mesh...	#6
PSYMN Senior Member Simon Pereira Join Date: Mar 2009 Location: Ann Arbor, MI Posts: 2,663 Blog Entries: 1 Rep Power: 47	Ok, I just took a quick of your attachment and see that this is just about quality metrics. I am curious about why you were doing this research... I checked (on my own and fired off an email to development and doc) and see that the doc is correct. Your examples are not. Both of these checks are looking for surface elements (triangles), you have provided volume elements (Tetrahedrals). So Overlapping elements is not usable because it only works on surface elements (TRI_3 and QUAD_4). It checks for all surface element edges if the any angle of the vector between the centroid of the surface element and the mid point of the element edge projected into the surface element plane and the vector between the centroid of a surface neighbor element and the mid point of the element edge projected into the surface neighbor element plane is less than 5 degrees. If so this will be marked as an overlap. These can cause a problem for delaunay because it is difficult to fit a decent tetra between the overlapping tris. The Delaunay check is similar. it is meant to be run before delaunay, so it applies to tri elements only (which it says in the first few words of the doc.) Just a side note; Most Delaunay meshers are now much more robust and failing the delaunay check is no longer a concern. I usually just skip it and focus more on the critical issues of single edges and overlapping elements.... Cecilia Zhang likes this.

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April 23, 2010, 00:03		#2
peter.wang New Member peter wang Join Date: Apr 2010 Posts: 4 Rep Power: 16	Why not hand? I'm waiting online!

April 23, 2010, 00:04		#3
peter.wang New Member peter wang Join Date: Apr 2010 Posts: 4 Rep Power: 16	Please help me!