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[blockMesh] blockMesh gives "Inconsistent point locations" for axisymmetric problem

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Old   November 5, 2013, 21:19
Default blockMesh gives "Inconsistent point locations" for axisymmetric problem
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Geoffrey Irving
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blockMesh is bailing when I give it two ungraded prisms. The output from blockMesh and the blockMeshDict are attached (I had to add a .txt extension to the latter to get it to upload).

The unusual bit of blockMesh output is me adding print statements to blockMesh to check whether it was a precision issue (based on http://www.cfd-online.com/Forums/ope...anslation.html). It doesn't appear to be precision related. It's also clearly not grading, since I'm asking for one cell in all dimensions.

Thanks in advance for any suggestions!
Attached Files
File Type: txt blockMesh.txt (2.8 KB, 19 views)
File Type: txt blockMeshDict.txt (757 Bytes, 7 views)
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Old   November 5, 2013, 21:24
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Here are excepts of both files for convenience, since looking at attachments seems bothersome.

Code:
# blockMeshDict exerpt
vertices (
  (0 0 0)
  (0 1.375 -0.0119991)
  (0 1.375 0.0119991)
  (3 0 0)
  (3 1.375 -0.0119991)
  (3 1.375 0.0119991)
  (6 0 0)
  (6 1.375 -0.0119991)
  (6 1.375 0.0119991)
);
blocks (
  prism (0 1 2 3 4 5) (1 1 1) simpleGrading (1 1 1)
  prism (3 4 5 6 7 8) (1 1 1) simpleGrading (1 1 1)
);
Code:
# blockMesh output
--> FOAM FATAL ERROR:
Inconsistent point locations between block pair 0 and 1, point 0
    probably due to inconsistent grading.

    From function blockMesh::calcMergeInfo()
    in file blockMesh/blockMeshMerge.C at line 313.
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Old   November 11, 2013, 10:10
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Jason Lassaline
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I've looked into this problem as I was experiencing similar issues. The problem appears to be with the merging of points in
src/mesh/blockMesh/blockMesh/blockMeshMerge.C. I found that not all points along the sharp edge of the wedge were being merged correctly, perhaps due to a truncation issue.

I increased mergeSqrDist at line 121 in Foam::blockMesh::calcMergeInfo by a factor of 100 to guarantee all points along this edge were merged correctly
const scalar mergeSqrDist = magSqr(10*SMALL*bb.span());
and now all wedge-shaped blocks are handled correctly. A factor of SMALL seems to be just a bit too small.
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Last edited by jvl001; November 11, 2013 at 11:14. Reason: Correction to factor.
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Old   July 8, 2014, 01:11
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Quote:
Originally Posted by jvl001 View Post
I've looked into this problem as I was experiencing similar issues. The problem appears to be with the merging of points in
src/mesh/blockMesh/blockMesh/blockMeshMerge.C. I found that not all points along the sharp edge of the wedge were being merged correctly, perhaps due to a truncation issue.

I increased mergeSqrDist at line 121 in Foam::blockMesh::calcMergeInfo by a factor of 100 to guarantee all points along this edge were merged correctly
const scalar mergeSqrDist = magSqr(10*SMALL*bb.span());
and now all wedge-shaped blocks are handled correctly. A factor of SMALL seems to be just a bit too small.
Dear jvl001
Thank you so much for your invaluable comment. I literally wasted 2 days on this issue
Best
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Old   August 7, 2014, 03:28
Default Same trouble
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Gareth
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Hi guys

I am having a similar issue

"Creating merge list

--> FOAM FATAL ERROR:
Inconsistent point locations between block pair 0 and 1
probably due to inconsistent grading.

From function blockMesh::calcMergeInfo()
in file blockMesh/blockMeshMerge.C at line 294.

FOAM exiting
"

I tried, blindly i might added, adjusting the blockMEshMerge.C file as indicated above but it didnt change the results.

This in an exert from my blockMeshDict:

blocks
(
hex (0 6 60 1 30 36 64 31) blade (10 10 1) simpleGrading (1 1 1)
prism (6 7 60 36 37 64) blade (10 10 1) simpleGrading (1 1 1)
hex (7 8 61 60 37 38 65 64) blade (10 10 1) simpleGrading (1 1 1)
hex (8 9 62 61 38 39 66 65) blade (10 10 1) simpleGrading (1 1 1)
prism (9 10 62 39 40 66) blade (10 10 1) simpleGrading (1 1 1)
hex (62 10 2 1 66 40 32 31) blade (10 10 1) simpleGrading (1 1 1)
prism (63 62 1 67 66 31) blade (10 10 1) simpleGrading (1 1 1)
prism (60 63 1 64 67 31) blade (10 10 1) simpleGrading (1 1 1)
hex (2 10 11 3 32 40 41 33) blade (10 10 1) simpleGrading (1 1 1)
hex (3 11 12 4 33 41 42 34) blade (10 10 1) simpleGrading (1 1 1)
hex (4 12 13 5 34 42 43 35) blade (10 10 1) simpleGrading (1 1 1)
hex (5 13 6 0 35 43 36 30) blade (10 10 1) simpleGrading (1 1 1)
hex (14 22 23 15 44 52 53 45) (10 10 1) simpleGrading (1 1 1)
hex (15 23 24 16 45 53 54 46) (10 10 1) simpleGrading (1 1 1)
hex (16 24 25 17 46 54 55 47) (10 10 1) simpleGrading (1 1 1)
hex (17 25 26 18 47 55 56 48) (10 10 1) simpleGrading (1 1 1)
hex (18 26 27 19 48 56 57 49) (10 10 1) simpleGrading (1 1 1)
hex (19 27 28 20 49 57 58 50) (10 10 1) simpleGrading (1 1 1)
hex (20 28 29 21 50 58 59 51) (10 10 1) simpleGrading (1 1 1)
hex (21 29 22 14 51 59 52 44) (10 10 1) simpleGrading (1 1 1)
);

If anyone can help me out...
I also attached the full file to this reply.
/* No real solution but since i asked somethign similar elsewhere i, thought i should link it
http://www.cfd-online.com/Forums/ope...use-prism.html
*/
Attached Files
File Type: txt blocks.txt (21.3 KB, 3 views)

Last edited by bullmut; August 7, 2014 at 09:17. Reason: Used a work around to solve
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Old   January 27, 2021, 12:23
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Sophie Larrivée-Larouche
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Many years have passed, I hope you are still there to answer

I would like to modify the source code of blockMeshMerge.C to correct an error similar to OP's reporter error (grading inconsistency), but the file is locked and can only be opened as readonly. Maybe this is a Linux thing, possibly a stupid question, but how can I modify the source code to test your solution?
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Old   January 27, 2021, 13:27
Default Alas, 7 years is too much
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Geoffrey Irving
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I've changed jobs 4 times since then, and also jumped from computational physics to AGI safety.
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Old   January 27, 2021, 13:31
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Sophie Larrivée-Larouche
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Ho well ! Good for you !

I realized I just had to use sudo before opening the file with gedit ! Also found my issue had nothing to do with that, and just solved it 2 minutes ago.

Thank you for taking the time to reply though !

Have a good day !
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