[ICEM] penetrating elements

robboflea · July 29, 2013, 13:27

I am having problems with penetrating elements coming out of my mesh check and I don't know how to get rid of them. I am modelling a 3d turbine airfoil and my penetrating elements all lay on hub surface or at the interface between the blade and the endwalls. Attached are some pictures, the penetrating elements are the red subset. There are a few visible (though quite small elements) as red lines on the blue blade edges at the tip and some at the hub.

What can be the reasons for having penetrating elements? What are the most common ways to solve the problem?

Thanks a lot in advance!

cesarcg · July 31, 2013, 10:14

If you are using the blocking method, this can be an issue of vertex to point and edges to curves association. You should also check if the faces are being associated to the surfaces you want them to, otherwise, correct that.

Let me know whether yes or no you solve the problem.

Regards

robboflea · July 31, 2013, 19:43

Thanks for the hint.

I double checked and it looks like all curves are associated correctly (at least I think so), so the vertices and the block faces.
Any other ideas?

Thanks

Rob

cesarcg · July 31, 2013, 20:03

Could you post some pictures of the blocking in the region that you are having problems with the penetrating elements?

Regards.
César

sadjad.s · August 1, 2013, 05:31

Hi mate,
i encountered this error while i was working with blocking and converting to unstructured mesh and using mirror option. (under transform options).
But when i exported it to fluent there was no problem.
So ignore it and export it to make a try.

robboflea · August 1, 2013, 05:36

I'll give a try in Fluent and see if it gives back something reasonable.
Thanks for the hint

Rob

PSYMN · August 1, 2013, 14:17

Run a cutplane or scan plane across the trailing edge and zoom in to see the reason why...

Far · August 1, 2013, 14:24

Are you using ICEM CFD HEXA? If yes can you show some blocking pics?

robboflea · August 3, 2013, 10:57

Hi Far,

yes I am using hexa meshing. Attached is a picture of the blocking. Is a "shifted periodic" blocking.

Far · August 3, 2013, 11:31

Use scan plan to pinpoint the problem area as suggested by Simon.

For further details take a look on following thread. Simon has given a detailed explanation of many options in ICEM CFD Hexa for turbomachinery meshing.

http://www.cfd-online.com/Forums/ans...l-turbine.html

robboflea · August 3, 2013, 15:31

Thanks for the hint. I am still not able to come to anything meaningful as an explanation. Btw what is the exact definition of "penetrating element"? From the manual I seem to understand that they are elements, laying on external surfaces who intersect other surface elements.

If I am correct then penetrating elements should always be numbered in couples. Am I right? Why when I create a subset out of my problematic elements I see these penetrating elements alone?

Sorry for the question if it sounds stupid.
Thanks for the help

Rob

August 1, 2013, 05:31	Answer	#5
sadjad.s Member sadjad Join Date: Jan 2012 Posts: 72 Rep Power: 14	Hi mate, i encountered this error while i was working with blocking and converting to unstructured mesh and using mirror option. (under transform options). But when i exported it to fluent there was no problem. So ignore it and export it to make a try. __________________ ICEM, CFX and Fluent expert

August 1, 2013, 14:17		#7
PSYMN Senior Member Simon Pereira Join Date: Mar 2009 Location: Ann Arbor, MI Posts: 2,663 Blog Entries: 1 Rep Power: 47	Run a cutplane or scan plane across the trailing edge and zoom in to see the reason why... __________________ ----------------------------------------- Please help guide development at ANSYS by filling in these surveys Public ANSYS ICEM CFD Users Survey This second one is more general (Gambit, TGrid and ANSYS Meshing users welcome)... CFD Online Users Survey

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July 31, 2013, 10:14		#2
cesarcg Member Cesar Join Date: Nov 2012 Location: Guanajuato, México Posts: 78 Rep Power: 16	If you are using the blocking method, this can be an issue of vertex to point and edges to curves association. You should also check if the faces are being associated to the surfaces you want them to, otherwise, correct that. Let me know whether yes or no you solve the problem. Regards

July 31, 2013, 19:43		#3
robboflea Senior Member Join Date: Nov 2011 Posts: 109 Rep Power: 15	Thanks for the hint. I double checked and it looks like all curves are associated correctly (at least I think so), so the vertices and the block faces. Any other ideas? Thanks Rob

July 31, 2013, 20:03		#4
cesarcg Member Cesar Join Date: Nov 2012 Location: Guanajuato, México Posts: 78 Rep Power: 16	Could you post some pictures of the blocking in the region that you are having problems with the penetrating elements? Regards. César

August 1, 2013, 05:36		#6
robboflea Senior Member Join Date: Nov 2011 Posts: 109 Rep Power: 15	I'll give a try in Fluent and see if it gives back something reasonable. Thanks for the hint Rob

August 1, 2013, 14:24		#8
Far Senior Member Sijal Join Date: Mar 2009 Location: Islamabad Posts: 4,558 Blog Entries: 6 Rep Power: 54	Are you using ICEM CFD HEXA? If yes can you show some blocking pics?

August 3, 2013, 11:31		#10
Far Senior Member Sijal Join Date: Mar 2009 Location: Islamabad Posts: 4,558 Blog Entries: 6 Rep Power: 54	Use scan plan to pinpoint the problem area as suggested by Simon. For further details take a look on following thread. Simon has given a detailed explanation of many options in ICEM CFD Hexa for turbomachinery meshing. http://www.cfd-online.com/Forums/ans...l-turbine.html

August 3, 2013, 15:31		#11
robboflea Senior Member Join Date: Nov 2011 Posts: 109 Rep Power: 15	Thanks for the hint. I am still not able to come to anything meaningful as an explanation. Btw what is the exact definition of "penetrating element"? From the manual I seem to understand that they are elements, laying on external surfaces who intersect other surface elements. If I am correct then penetrating elements should always be numbered in couples. Am I right? Why when I create a subset out of my problematic elements I see these penetrating elements alone? Sorry for the question if it sounds stupid. Thanks for the help Rob