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[ICEM] Bad quality surface mesh elements at curve

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Old   December 11, 2014, 10:56
Lightbulb Bad quality surface mesh elements at curve
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Benjamin Hogan
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Hi there,

Relatively new to ICEM CFD. I am meshing a streamlined land based vehicle and have encountered a small problem.

I am using a tetra-prism mesh.

For some reason at the trailing edge of the car, where the car's surface meets the symmetry plane, when I use the Octree mesher the surface mesh doesnt seem to stick to the last curve?



I have tried remeshing the bad elements along the curve, but instead it appears to ignore the curve completely?



Any help would be greatly appreciated. Cheers!

Ben
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Old   December 12, 2014, 09:29
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You need to find and use the "Edge Criterion" control. Search the help or CFD-Online for more info.
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Old   December 12, 2014, 10:39
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read this ->> https://docs.google.com/file/d/0ByIL...BQT3pQMjQ/edit
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New to ICEM CFD, try this document --> https://goo.gl/KAOIwm
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Old   December 12, 2014, 20:45
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Hi Simon,

Thanks for your reply. I have thoroughly experimented with edge criterion today and whilst decreasing the 'edge criterion' made the problem significantly worse, and increasing the 'edge criterion' improved the situation with a reduced the number of bad cells, it has not solved my problem.

Under closer inspection it turns out that a few cells all around the domain are occasionally not sticking to the curve?

I have attached a few more images that I hope explain the problem a bit more.

Any help or advice would be greatly appreciated - this is really driving me bonkers!





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Old   December 12, 2014, 20:48
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For those few cells, you can repair them manually, under the edit mesh tab -> move node -> project node to curve, select those nodes, and VOILA
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Old   December 12, 2014, 20:58
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Hi DiamondX,

Thanks for your reply - very helpful. This would work if I were to perform the action on each of the bad cells.

I am wondering why this problem has started to happen all of a sudden? I have meshed very similar geometries previous to this and have not had the above problem?

Would it be something in general mesh settings? Any thoughts?

Cheers!

Ben
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Old   December 12, 2014, 21:01
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Today, it happened to me. I was using the "move node" option, after some saving and re-opening, I didn't have to use it. I really don't know... Make a super zoom on that curve, see if it's really attached to the surface maybe ?!
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Old   December 13, 2014, 08:59
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I have tried changing the geometry, refining the mesh, coarsening the mesh, altering the edge criterion and still no luck.



If anyone has any thoughts or suggestions please let me know.
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Old   December 13, 2014, 15:03
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Define a node spacing for the red curve via curve mesh setup. Use the maxsize (or smaller) of the smaller surface elements. You can preview the nodespacing by activating it in displaytree (RMB on curves).
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