periodic setting

amin.z · September 23, 2014, 08:16

Hi

Sometimes I have a problem with generating periodic BC!
With a same grid, sometimes I could generate periodic BC but sometimes I face this error:
"Zone xx has inconsistent periodic setting"

What's the problem? Is mesh quality reason of this error? Or...?

Tnx

ghost82 · September 23, 2014, 08:39

I think that the problem comes because the 2 periodic faces have not the same mesh; when you set the periodic bc, both faces must have exactly the same mesh; in gambit I always use the "link" function to be sure to have the same mesh.
Moreover, take care to the axis coordinates: I had a case where the origin was not exactly in 0,0,0 but something like 1e-4,1e-4,0 and that caused an error.

Daniele

amin.z · September 23, 2014, 08:47

Dear friend! I'm checked this points and it's ok! I'm using ANSYS Meshing and in that using "match control" for linking mesh!
The strange point is this error occurs for a mesh that I set periodic BC already without any error!

amin.z · September 23, 2014, 08:49

And I should say this error occurs when I check the mesh! The periodic BC was set! But mesh check failed...

ghost82 · September 23, 2014, 08:54

It's quite difficult to say what causes this error, can you share the mesh or the cas file (also in private)?

PS: I'm not using ansys meshing so if you want share msh file or cas file.

amin.z · September 23, 2014, 08:59

Now I'm in my office and commenting with my iPad! So I cannot share anything!
If the problem don't solved, about 3 hours later I will come back home and sent something for you!

ghost82 · September 23, 2014, 09:04

Ok!
In the meantime check in the general tab what are max/min x,y,z to see if you set correctly axys origin coordinates.

amin.z · September 23, 2014, 11:11

Dear daniele!
The problem solved!
I find out in the periodic BC generating, arrangement is important and effective!
In the mesh check some faces had periodic angle of 60 degrees and other had periodic angle of -60 degrees!
This was amazing! Although you knew that!

skarthik · July 21, 2015, 09:32

Hey Amin and Daniele,

I am facing a similar problem. How did you solve the previous one?
I apply cyclic region symmetry and match control without any errors. But when I click 'generate mesh' it says that the "The mesher cannot determine a matching face/edge for the following face/edge with periodic boundary conditions. Please verify that the topology is the same shape and size. Also verify the position and orientation of any associated coordinate systems."

Refer the attached image. It is a gas turbine combustor and the inner chamber has a swirler at the inlet. The periodicity is 51.42degrees as the swirler has 7 vanes. I believe the error has something to do with the swirler because when I tried to remove the swirler and run it, it meshed without any errors.

1.jpg

2.jpg

Please let me know how you solved you solved this. I am stuck with this for the past 3 days!

PS- As a side question, is there another way to impart a swirl at the plane where the inlet gases enter the inner chamber so that I can do away with the swirler?

Thanks!!!
Karthik S

amin.z · July 22, 2015, 01:24

Hi,

Have you checked the topology? Is it okay?
and
Have you create a cylindrical coordinate system for your mesh control?

skarthik · July 22, 2015, 03:51

Hey Amin,

Thanks for the reply.. Yes I have created a cylindrical coordinate system.
7.JPG

What do you mean check topology? I visually checked them an the seem similar. Is there any automated way to check them?

6.jpg

5.jpg

amin.z · July 22, 2015, 03:58

use design modeler, select each face you wanna set as periodic and ensure corresponding periodic faces have same area and edges quantities,

If it's okay, then try to generate mesh for each part lonely! suppress other parts and check it for each part separately

skarthik · July 22, 2015, 04:06

Ah I see. They are not having the same values.

The number of edges and vertices are the same, but the area is different by a few mm2.. 8517 on one face and 8512 on the other.

mehtakrunal · September 8, 2016, 06:58

Quote:

Originally Posted by skarthik

Ah I see. They are not having the same values.

The number of edges and vertices are the same, but the area is different by a few mm2.. 8517 on one face and 8512 on the other.

Hello did you find solution to this.. i am facing same issue.. mismatch in area and cyclic sym is declined

September 23, 2014, 08:16	periodic setting	#1
amin.z Senior Member Amin Join Date: Oct 2013 Location: Germany Posts: 397 Rep Power: 14	Hi Sometimes I have a problem with generating periodic BC! With a same grid, sometimes I could generate periodic BC but sometimes I face this error: "Zone xx has inconsistent periodic setting" What's the problem? Is mesh quality reason of this error? Or...? Tnx

September 23, 2014, 11:11		#8
amin.z Senior Member Amin Join Date: Oct 2013 Location: Germany Posts: 397 Rep Power: 14	Dear daniele! The problem solved! I find out in the periodic BC generating, arrangement is important and effective! In the mesh check some faces had periodic angle of 60 degrees and other had periodic angle of -60 degrees! This was amazing! Although you knew that! ghost82 likes this.

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September 23, 2014, 08:39		#2
ghost82 Senior Member Rick Join Date: Oct 2010 Posts: 1,016 Rep Power: 26	I think that the problem comes because the 2 periodic faces have not the same mesh; when you set the periodic bc, both faces must have exactly the same mesh; in gambit I always use the "link" function to be sure to have the same mesh. Moreover, take care to the axis coordinates: I had a case where the origin was not exactly in 0,0,0 but something like 1e-4,1e-4,0 and that caused an error. Daniele

September 23, 2014, 08:47		#3
amin.z Senior Member Amin Join Date: Oct 2013 Location: Germany Posts: 397 Rep Power: 14	Dear friend! I'm checked this points and it's ok! I'm using ANSYS Meshing and in that using "match control" for linking mesh! The strange point is this error occurs for a mesh that I set periodic BC already without any error!

September 23, 2014, 08:49		#4
amin.z Senior Member Amin Join Date: Oct 2013 Location: Germany Posts: 397 Rep Power: 14	And I should say this error occurs when I check the mesh! The periodic BC was set! But mesh check failed...

September 23, 2014, 08:54		#5
ghost82 Senior Member Rick Join Date: Oct 2010 Posts: 1,016 Rep Power: 26	It's quite difficult to say what causes this error, can you share the mesh or the cas file (also in private)? PS: I'm not using ansys meshing so if you want share msh file or cas file.

September 23, 2014, 08:59		#6
amin.z Senior Member Amin Join Date: Oct 2013 Location: Germany Posts: 397 Rep Power: 14	Now I'm in my office and commenting with my iPad! So I cannot share anything! If the problem don't solved, about 3 hours later I will come back home and sent something for you!

September 23, 2014, 09:04		#7
ghost82 Senior Member Rick Join Date: Oct 2010 Posts: 1,016 Rep Power: 26	Ok! In the meantime check in the general tab what are max/min x,y,z to see if you set correctly axys origin coordinates.

July 21, 2015, 09:32		#9
skarthik New Member Karthik S Join Date: Jul 2015 Posts: 18 Rep Power: 10	Hey Amin and Daniele, I am facing a similar problem. How did you solve the previous one? I apply cyclic region symmetry and match control without any errors. But when I click 'generate mesh' it says that the "The mesher cannot determine a matching face/edge for the following face/edge with periodic boundary conditions. Please verify that the topology is the same shape and size. Also verify the position and orientation of any associated coordinate systems." Refer the attached image. It is a gas turbine combustor and the inner chamber has a swirler at the inlet. The periodicity is 51.42degrees as the swirler has 7 vanes. I believe the error has something to do with the swirler because when I tried to remove the swirler and run it, it meshed without any errors. 1.jpg 2.jpg Please let me know how you solved you solved this. I am stuck with this for the past 3 days! PS- As a side question, is there another way to impart a swirl at the plane where the inlet gases enter the inner chamber so that I can do away with the swirler? Thanks!!! Karthik S

July 22, 2015, 01:24		#10
amin.z Senior Member Amin Join Date: Oct 2013 Location: Germany Posts: 397 Rep Power: 14	Hi, Have you checked the topology? Is it okay? and Have you create a cylindrical coordinate system for your mesh control?

July 22, 2015, 03:51		#11
skarthik New Member Karthik S Join Date: Jul 2015 Posts: 18 Rep Power: 10	Hey Amin, Thanks for the reply.. Yes I have created a cylindrical coordinate system. 7.JPG What do you mean check topology? I visually checked them an the seem similar. Is there any automated way to check them? 6.jpg 5.jpg

July 22, 2015, 03:58		#12
amin.z Senior Member Amin Join Date: Oct 2013 Location: Germany Posts: 397 Rep Power: 14	use design modeler, select each face you wanna set as periodic and ensure corresponding periodic faces have same area and edges quantities, If it's okay, then try to generate mesh for each part lonely! suppress other parts and check it for each part separately

July 22, 2015, 04:06		#13
skarthik New Member Karthik S Join Date: Jul 2015 Posts: 18 Rep Power: 10	Ah I see. They are not having the same values. The number of edges and vertices are the same, but the area is different by a few mm2.. 8517 on one face and 8512 on the other.