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[ICEM] Negative element volumes

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Old   March 24, 2014, 04:59
Default Negative element volumes
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Hi,

I tried to mesh the geometry (see Geometry.png) as a structured grid with hexas. The problematic area is marked with a red frame. When importing the mesh in CFX and try to run it, a message pops up saying that there are some negative elements (see Primitive2D.png). The blocks in the problematic region can be seen in Blocks.png. I tried to get rid of those elements by refining the mesh or changing the blocks slightly, but nothing helped. There is a rather small gap between the pipe and the lid. Somehow the mesher can't cope with the region lying behind this geometry. Anyone an idea?

Best regards.
G.
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File Type: png Geometry.png (22.5 KB, 7 views)
File Type: jpg Blocks.jpg (43.8 KB, 6 views)
File Type: png Primitive2D.png (21.8 KB, 5 views)
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Old   March 24, 2014, 06:04
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Ludvik Lanicek
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In Blocking use "Block Check" (red tag button) and select "Fix Inverted Blocks". In Edit Mesh try "Check Mesh" and "Volume Orientation".
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Old   March 24, 2014, 11:53
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Hi,

that was a nice hint as ICEM detects the problematic area but did not really solve the problem. I said "Fix" when error messages occured in the "Check Mesh" process. But the "Negative element volume" error still persists in CFX.

Any other idea?

Best regards.
J.
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Old   April 4, 2014, 09:30
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Hi,

I finally solved the problem. "Edit Mesh" -> "Check Mesh" could not fix all the problematic elements and stated "that the elements were too bad to be fixed." So sometimes, the fixing process fails. I changed the blocks I used by making them slightly larger at some edges and suddenly it worked. So it was just "try and error" strategy and a little bit of luck.

Best regards.
G.
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