getting unwanted internal faces

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 November 13, 2014, 02:57 getting unwanted internal faces #1 New Member   Arjun Join Date: Jan 2014 Location: Chennai Posts: 21 Rep Power: 3 Dear all, I am new to blockMesh utility. I have attached my domain with corresponding vertices numbering. I want to divide my domain in to four as marked in the figure. for that following codes are used: hex(0 1 2 8 10 11 12 18) (10 10 1) simpleGrading (1 1 1) //block 0 hex(8 2 3 7 18 12 13 17) (10 10 1) simpleGrading (1 1 1) //block 1 hex(7 9 5 6 17 19 15 16) (10 10 1) simpleGrading (1 1 1) //block 2 hex(9 3 4 5 19 13 14 15) (10 10 1) simpleGrading (1 1 1) //block 3 But i am getting two internal face, its orientation is (7 17 9 19) and (9 19 3 13) I want to get rid of this internal face. Or help me with any other condition that will nullify the effect of internal face. DSC_1749.jpg Last edited by Arjun Jayakumar; November 13, 2014 at 04:52.

November 13, 2014, 05:19
#2
Senior Member

Tushar Chourushi
Join Date: Jul 2009
Location: IIT-Indore, India
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Quote:
 Originally Posted by Arjun Jayakumar Dear all, I am new to blockMesh utility. I have attached my domain with corresponding vertices numbering. I want to divide my domain in to four as marked in the figure. for that following codes are used: hex(0 1 2 8 10 11 12 18) (10 10 1) simpleGrading (1 1 1) //block 0 hex(8 2 3 7 18 12 13 17) (10 10 1) simpleGrading (1 1 1) //block 1 hex(7 9 5 6 17 19 15 16) (10 10 1) simpleGrading (1 1 1) //block 2 hex(9 3 4 5 19 13 14 15) (10 10 1) simpleGrading (1 1 1) //block 3 But i am getting two internal face, its orientation is (7 17 9 19) and (9 19 3 13) I want to get rid of this internal face. Or help me with any other condition that will nullify the effect of internal face. Attachment 35071
I would rather create blocks out of nodes (9,19) and divide block 0 and 1, similar to block 2 and 3.

Anyways, try defining your Boundary Conditions like this,

defaultFaces
{
type empty;
}

-
Best Luck!

November 13, 2014, 06:02
#3
New Member

Arjun
Join Date: Jan 2014
Location: Chennai
Posts: 21
Rep Power: 3
Quote:
 Originally Posted by Tushar@cfd I would rather create blocks out of nodes (9,19) and divide block 0 and 1, similar to block 2 and 3. Anyways, try defining your Boundary Conditions like this, defaultFaces { type empty; } Re-run your case, I hope it will solve your problem. - Best Luck!
dear tushar,

I have already tried this by setting the defaultfaces to empty but this will not help to solve the problem.
Its showing higher velocities at the patch surface, which result in too high courant number.
Do you know how i am getting these internal faces, without defining any where in the blockMesh dictionary.

November 13, 2014, 06:34
#4
Senior Member

Tushar Chourushi
Join Date: Jul 2009
Location: IIT-Indore, India
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Quote:
 Originally Posted by Arjun Jayakumar dear tushar, thank you for your time. I have already tried this by setting the defaultfaces to empty but this will not help to solve the problem. Its showing higher velocities at the patch surface, which result in too high courant number. Do you know how i am getting these internal faces, without defining any where in the blockMesh dictionary.
Dear Arjun,

The error is in the blockMesh, due to node (9, 19) which is connected to a face. If you remove this node and use only 3 blocks it will work, as it will follows the block rule.

If your case demands such mesh only. Then, you can try "merge" option of OpenFOAM. Although, I never tried it but I think that will help you resolve.

Please, do share to FOAM community if you happen to get correct solutions.

-
Best Luck!

November 13, 2014, 07:36
#5
New Member

Arjun
Join Date: Jan 2014
Location: Chennai
Posts: 21
Rep Power: 3
Quote:
 Originally Posted by Tushar@cfd Dear Arjun, The error is in the blockMesh, due to node (9, 19) which is connected to a face. If you remove this node and use only 3 blocks it will work, as it will follows the block rule. If your case demands such mesh only. Then, you can try "merge" option of OpenFOAM. Although, I never tried it but I think that will help you resolve. Please, do share to FOAM community if you happen to get correct solutions. - Best Luck!
dear tushar,

I need to define a patch on face (4 14 15 5).

If i try with 3 blocks it will lead to error "face 0 in patch 0 does not have neighbour cell face: 4(4 14 15 5).

I am not familiar with merge. which all faces do you suggest to merge.

Thank you

November 13, 2014, 08:20
#6
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Tushar Chourushi
Join Date: Jul 2009
Location: IIT-Indore, India
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Quote:
 Originally Posted by Arjun Jayakumar dear tushar, I need to define a patch on face (4 14 15 5). If i try with 3 blocks it will lead to error "face 0 in patch 0 does not have neighbour cell face: 4(4 14 15 5). I am not familiar with merge. which all faces do you suggest to merge. Thank you
Dear Arjun,

You can easily construct 3 block for the case which you have referred in the figure. Follow carefully the blockMesh strategy of OpenFOAM, refer link below for the same:

http://www.openfoam.org/docs/user/blockMesh.php

For merge patch I am not an expert. You can explore it.

-
Best Luck!

 November 13, 2014, 15:03 #7 Senior Member     Marco A. Turcios Join Date: Mar 2009 Location: Vancouver, BC, Canada Posts: 727 Rep Power: 18 An alternative method is to generate the 3-block mesh which works, then use topoSet to select the faces that correspond to face 4 14 15 5 and use createPatch to generate the boundary patch. I've found this approach is more consistent and allows you to make all kinds of boundary patches that only partially cover the domain boundaries, and requires less debugging of the blockMesh dict file which can become a real headache.

November 14, 2014, 07:48
#8
New Member

Arjun
Join Date: Jan 2014
Location: Chennai
Posts: 21
Rep Power: 3
Quote:
 Originally Posted by mturcios777 An alternative method is to generate the 3-block mesh which works, then use topoSet to select the faces that correspond to face 4 14 15 5 and use createPatch to generate the boundary patch. I've found this approach is more consistent and allows you to make all kinds of boundary patches that only partially cover the domain boundaries, and requires less debugging of the blockMesh dict file which can become a real headache.
Thank you for your suggestion Marco. I think it will take some time for me to familiarize with topoSet utility. Will post the updates and looking forward to your help in future.

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