[ICEM] not completing mesh of the surface

m5edr · March 17, 2012, 10:41

This is a turbine blade
After many trials , the mesh of the surface is not cover the whole bade (specially along the trailing edge !!)

iam used various mesh types in Icem and played with mesh sizes but not able to solve this problem

Any help pls

rikio · March 17, 2012, 20:16

You need to adjust the Edge Criterion under Volume Meshing Parameters. It determines to what extent a tetra is cut to represent geometry. The entered value is a factor of the tetra edge. After subdivision, if a tetra edge intersects an entity (surface), the tetra will be cut if the subdivision of the edge from the intersection is less than the prescribed value.

Looking into this thread at Help at Mesh-Global Mesh Setup-Volume Meshing Parameters-Tetra/Mixed-Robust(Octree)

PSYMN · March 19, 2012, 11:07

Or turn on "thin cuts"

You may also need to reduce your mesh size.

This is a "behavior" associated with Octree mesh.

Another option would be to use another method (such as Patch Conforming Surface Mesh)...

m5edr · March 19, 2012, 11:45

Yes, i discovered that 1 day ago >>>> thin cut solve the problem

thanks

andrearudenick · March 21, 2012, 09:52

When you say "turn on thin cuts", do you mean to turn on the function "Define thin cuts" of the Volume Meshing Parameters section? or is there another ICEM function applied to shell meshing instead of volumen meshing? Because at the beginning you were talking about a surface mesh, and I'm having the same problem.

Thanks!

m5edr · March 21, 2012, 10:04

Quote:

Originally Posted by andrearudenick

When you say "turn on thin cuts", do you mean to turn on the function "Define thin cuts" of the Volume Meshing Parameters section? or is there another ICEM function applied to shell meshing instead of volumen meshing? Because at the beginning you were talking about a surface mesh, and I'm having the same problem.

Thanks!

I mean "Define thin cuts" of the Volume Meshing Parameters section"
but first you should create two parts (of thin cut) at CREATE PART

PSYMN · March 21, 2012, 10:12

Right, Define Thin Cuts affects how the surface mesh is produced with the "patch independent (Octree)" meshing approach.

It is essentially an algorithm that says "if a surface element has a node on part A, then it should not have a node on Part B." Therefore you need to make sure that the two sides are in different parts. Also, if the two sides meet at a common curve, the curve must be in a 3rd part (separate from the two sides) or it will be impossible for the algorithm to succeed and it will fail out with a message.

Best regards,

Simon

m5edr · March 21, 2012, 10:20

hi simon

iam very sorry for this overlap (I'm feel it awkward

)
I posted a problem in ICEM
could you show it

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

sorry again

PSYMN · March 21, 2012, 10:36

@m5edr...

Yes, I don't have time to read all the threads these days and I am missing more than I hit (I appreciate others on CFD-Online who can also help out).

If you want me to notice a thread, please don't pollute an unrelated thread. I would rather you just send me a private message with a link to the thread...

Best regards,

Simon

Ananthakrishnan · April 24, 2012, 18:30

Hi,
I had this problem and "define thin cut" did help. Now i have a different problem which is i am unable to create prism elements on the airfoil surfaces (these are the surface with which i have defined my "thin cut"). Is there anything i am missing??

m5edr · April 24, 2012, 18:37

Quote:

Originally Posted by Ananthakrishnan

Hi,
I had this problem and "define thin cut" did help. Now i have a different problem which is i am unable to create prism elements on the airfoil surfaces (these are the surface with which i have defined my "thin cut"). Is there anything i am missing??

check
1- if you checked "create prism layers" in Compute mesh window
2- if you checked "prism" in Part mesh setup window

Ananthakrishnan · April 25, 2012, 02:43

yeah..i have...
If i undefine the thin cut, then prism gets created. If i define thin cut, then it does'nt..

OneDotThree · April 25, 2012, 09:04

I'm replying to this posts as I have problem similar to the previous ones.

I'm trying to create an unstructured mesh for a swirler. In fact I'm meshing 1/8 of the swirler and applying periodic conditions.

The problem is that some elements miss in proximity of some periodic face edges and appear in the corresponding periodic surface. in other words there is a hole at one side and there are exceeding elements (outside the surface) at the other side.

Moreover these elements have a low quality (below 0.2), so I can't ignore them.

I tried to use the define thin cutsoption and to define different values in the edge criterion but I couldn't resolve the problem.

I'm attaching some picture to explain better:
Attachment 12730 Attachment 12731 Attachment 12732

In the first picture in green you can see the periodic faces, in the second one the holes and in the third the elements outside the geometry.

I would be very grateful if someone could help me, thanks.

OneDotThree · May 5, 2012, 12:09

Could somebody give me an answer?
I resolved this problem accidentaly but it reappears if i change any mesh parameters (also in not involved parts).
It is very annoying, I've worked on it several days but I can't manage.
I would be able also to send you the project files.
Please help me!

March 17, 2012, 20:16		#2
rikio Senior Member Rikio Join Date: Mar 2009 Location: SH, China Posts: 182 Blog Entries: 1 Rep Power: 17	You need to adjust the Edge Criterion under Volume Meshing Parameters. It determines to what extent a tetra is cut to represent geometry. The entered value is a factor of the tetra edge. After subdivision, if a tetra edge intersects an entity (surface), the tetra will be cut if the subdivision of the edge from the intersection is less than the prescribed value. Looking into this thread at Help at Mesh-Global Mesh Setup-Volume Meshing Parameters-Tetra/Mixed-Robust(Octree) Dronzer likes this.

March 19, 2012, 11:07		#3
PSYMN Senior Member Simon Pereira Join Date: Mar 2009 Location: Ann Arbor, MI Posts: 2,663 Blog Entries: 1 Rep Power: 47	Or turn on "thin cuts" You may also need to reduce your mesh size. This is a "behavior" associated with Octree mesh. Another option would be to use another method (such as Patch Conforming Surface Mesh)... ahmadreza and Dronzer like this. __________________ ----------------------------------------- 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

March 21, 2012, 10:12		#7
PSYMN Senior Member Simon Pereira Join Date: Mar 2009 Location: Ann Arbor, MI Posts: 2,663 Blog Entries: 1 Rep Power: 47	Right, Define Thin Cuts affects how the surface mesh is produced with the "patch independent (Octree)" meshing approach. It is essentially an algorithm that says "if a surface element has a node on part A, then it should not have a node on Part B." Therefore you need to make sure that the two sides are in different parts. Also, if the two sides meet at a common curve, the curve must be in a 3rd part (separate from the two sides) or it will be impossible for the algorithm to succeed and it will fail out with a message. Best regards, Simon Far and dongjia like this. __________________ ----------------------------------------- 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

March 21, 2012, 10:36		#9
PSYMN Senior Member Simon Pereira Join Date: Mar 2009 Location: Ann Arbor, MI Posts: 2,663 Blog Entries: 1 Rep Power: 47	@m5edr... Yes, I don't have time to read all the threads these days and I am missing more than I hit (I appreciate others on CFD-Online who can also help out). If you want me to notice a thread, please don't pollute an unrelated thread. I would rather you just send me a private message with a link to the thread... Best regards, Simon __________________ ----------------------------------------- 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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March 19, 2012, 11:45		#4
m5edr Senior Member mohamed khedr emam Join Date: Oct 2011 Location: Egypt Posts: 121 Rep Power: 14	Yes, i discovered that 1 day ago >>>> thin cut solve the problem thanks

March 21, 2012, 09:52		#5
andrearudenick New Member Join Date: Mar 2012 Posts: 3 Rep Power: 14	When you say "turn on thin cuts", do you mean to turn on the function "Define thin cuts" of the Volume Meshing Parameters section? or is there another ICEM function applied to shell meshing instead of volumen meshing? Because at the beginning you were talking about a surface mesh, and I'm having the same problem. Thanks!

March 21, 2012, 10:20		#8
m5edr Senior Member mohamed khedr emam Join Date: Oct 2011 Location: Egypt Posts: 121 Rep Power: 14	hi simon iam very sorry for this overlap (I'm feel it awkward ) I posted a problem in ICEM could you show it http://www.cfd-online.com/Forums/ans...-periodic.html sorry again

April 24, 2012, 18:30		#10
Ananthakrishnan Senior Member Ananthakrishnan.A.S Join Date: Feb 2012 Location: Mumbai (Bombay), India Posts: 157 Rep Power: 16	Hi, I had this problem and "define thin cut" did help. Now i have a different problem which is i am unable to create prism elements on the airfoil surfaces (these are the surface with which i have defined my "thin cut"). Is there anything i am missing??

April 25, 2012, 02:43		#12
Ananthakrishnan Senior Member Ananthakrishnan.A.S Join Date: Feb 2012 Location: Mumbai (Bombay), India Posts: 157 Rep Power: 16	yeah..i have... If i undefine the thin cut, then prism gets created. If i define thin cut, then it does'nt..

April 25, 2012, 09:04		#13
OneDotThree New Member Sergio Macchiavello Join Date: Mar 2012 Posts: 7 Rep Power: 14	I'm replying to this posts as I have problem similar to the previous ones. I'm trying to create an unstructured mesh for a swirler. In fact I'm meshing 1/8 of the swirler and applying periodic conditions. The problem is that some elements miss in proximity of some periodic face edges and appear in the corresponding periodic surface. in other words there is a hole at one side and there are exceeding elements (outside the surface) at the other side. Moreover these elements have a low quality (below 0.2), so I can't ignore them. I tried to use the define thin cutsoption and to define different values in the edge criterion but I couldn't resolve the problem. I'm attaching some picture to explain better: Attachment 12730 Attachment 12731 Attachment 12732 In the first picture in green you can see the periodic faces, in the second one the holes and in the third the elements outside the geometry. I would be very grateful if someone could help me, thanks.

May 5, 2012, 12:09		#14
OneDotThree New Member Sergio Macchiavello Join Date: Mar 2012 Posts: 7 Rep Power: 14	Could somebody give me an answer? I resolved this problem accidentaly but it reappears if i change any mesh parameters (also in not involved parts). It is very annoying, I've worked on it several days but I can't manage. I would be able also to send you the project files. Please help me!