CFD Online Logo CFD Online URL
www.cfd-online.com
[Sponsors]
Home > Forums > OpenFOAM Native Meshers: blockMesh

round tube - checkMesh error

Register Blogs Members List Search Today's Posts Mark Forums Read

Reply
 
LinkBack Thread Tools Display Modes
Old   November 5, 2013, 12:02
Default round tube - checkMesh error
  #1
New Member
 
klemen
Join Date: Aug 2012
Location: Slovenia
Posts: 21
Rep Power: 5
fogl is on a distinguished road
When i made a straight tube and "checkMesh" i receive no errors. But when i add a 90 round tube on top, "checkMesh" returns 4 errors (please see below). I made a round tube using this instructions: defining and connecting two circular pipes using blockMesh

When i run paraFoam, everything looks nice. I tried to change the tube grading but this didn't solve the "High aspect ratio" problem. I have no idea how could i solved the non-orthogonality error - isn't this obveous that the faces will be non orthogonal if the tube is not straight?

Any idea how can i solve this problem?

Regards
Klemen


--------------------------
Checking geometry...
Overall domain bounding box (-0.008 -0.00654102 0.002) (0.00654102 0.00654102 0.0339986)
Mesh (non-empty, non-wedge) directions (1 1 1)
Mesh (non-empty) directions (1 1 1)
Boundary openness (-1.31732e-17 1.60882e-17 2.02306e-16) OK.
***High aspect ratio cells found, Max aspect ratio: 7.93329e+192, number of cells 330
<<Writing 330 cells with high aspect ratio to set highAspectRatioCells
Minimum face area = 1.05207e-23. Maximum face area = 6.85601e-07. Face area magnitudes OK.
Min volume = 1.66667e-300. Max volume = 1.87778e-10. Total volume = 2.065e-06. Cell volumes OK.
Mesh non-orthogonality Max: 180 average: 17.3038
*Number of severely non-orthogonal faces: 478.
***Number of non-orthogonality errors: 1103.
<<Writing 1581 non-orthogonal faces to set nonOrthoFaces
***Error in face pyramids: 2244 faces are incorrectly oriented.
<<Writing 1189 faces with incorrect orientation to set wrongOrientedFaces
***Max skewness = 8.04445, 7 highly skew faces detected which may impair the quality of the results
<<Writing 7 skew faces to set skewFaces
Coupled point location match (average 0) OK.
Failed 4 mesh checks.
fogl is offline   Reply With Quote

Old   November 13, 2013, 03:46
Default
  #2
Member
 
B T KANNAN
Join Date: Jul 2011
Location: CHENNAI (MADRAS), INDIA
Posts: 54
Rep Power: 6
skyinventorbt is on a distinguished road
Quote:
Originally Posted by fogl View Post
When i made a straight tube and "checkMesh" i receive no errors. But when i add a 90 round tube on top, "checkMesh" returns 4 errors (please see below). I made a round tube using this instructions: defining and connecting two circular pipes using blockMesh

When i run paraFoam, everything looks nice. I tried to change the tube grading but this didn't solve the "High aspect ratio" problem. I have no idea how could i solved the non-orthogonality error - isn't this obveous that the faces will be non orthogonal if the tube is not straight?

Any idea how can i solve this problem?

Regards
Klemen


--------------------------
Checking geometry...
Overall domain bounding box (-0.008 -0.00654102 0.002) (0.00654102 0.00654102 0.0339986)
Mesh (non-empty, non-wedge) directions (1 1 1)
Mesh (non-empty) directions (1 1 1)
Boundary openness (-1.31732e-17 1.60882e-17 2.02306e-16) OK.
***High aspect ratio cells found, Max aspect ratio: 7.93329e+192, number of cells 330
<<Writing 330 cells with high aspect ratio to set highAspectRatioCells
Minimum face area = 1.05207e-23. Maximum face area = 6.85601e-07. Face area magnitudes OK.
Min volume = 1.66667e-300. Max volume = 1.87778e-10. Total volume = 2.065e-06. Cell volumes OK.
Mesh non-orthogonality Max: 180 average: 17.3038
*Number of severely non-orthogonal faces: 478.
***Number of non-orthogonality errors: 1103.
<<Writing 1581 non-orthogonal faces to set nonOrthoFaces
***Error in face pyramids: 2244 faces are incorrectly oriented.
<<Writing 1189 faces with incorrect orientation to set wrongOrientedFaces
***Max skewness = 8.04445, 7 highly skew faces detected which may impair the quality of the results
<<Writing 7 skew faces to set skewFaces
Coupled point location match (average 0) OK.
Failed 4 mesh checks.
Reduce non-orthogonality, skewness etc.,
Try increasing the number of cells in the round tube.
--
KANNAN
skyinventorbt is offline   Reply With Quote

Old   July 9, 2014, 06:54
Default
  #3
New Member
 
Ali Heidari
Join Date: May 2013
Location: Tehran,Iran
Posts: 6
Rep Power: 5
Alih is on a distinguished road
hello klemen.
i have the same problem. can you solve this problem??
Thanks.

Regards
Alih is offline   Reply With Quote

Old   July 9, 2014, 15:17
Default
  #4
New Member
 
klemen
Join Date: Aug 2012
Location: Slovenia
Posts: 21
Rep Power: 5
fogl is on a distinguished road
Hello Ali,

I think i solved the problem by defining the circle (tube cross section) from five patches - a square in the middle and four curved trapezoids around the square.

I don't have the access to my computer at the moment, but i can check it next week - let me know if you don't succeed.

Regards
Klemen
fogl is offline   Reply With Quote

Old   July 10, 2014, 06:27
Default
  #5
New Member
 
Ali Heidari
Join Date: May 2013
Location: Tehran,Iran
Posts: 6
Rep Power: 5
Alih is on a distinguished road
Thank you very much Klemen.

My blockMesh file is:
code:
Code:
/*--------------------------------*- C++ -*----------------------------------*\
| =========                 |                                                 |
| \\      /  F ield         | OpenFOAM: The Open Source CFD Toolbox           |
|  \\    /   O peration     | Version:  2.2.1                                 |
|   \\  /    A nd           | Web:      www.OpenFOAM.com                      |
|    \\/     M anipulation  |                                                 |
\*---------------------------------------------------------------------------*/
FoamFile
{
    version     2.0;
    format      ascii;
    class       dictionary;
    object      blockMeshDict;
}
// * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * //

convertToMeters 0.01;

vertices        
(
    (0 8 2)        
    (10 0 1.5)    
    (10 3 2)    
    (1 8 2)    
    (0 8 0)    
    (10 0 0.5)    
    (10 3 1)    
    (1 8 0)    
);
blocks          
(
    hex (0 1 2 3 4 5 6 7) (40 15 10) simpleGrading (1 1 1)
);

edges           
(
);

boundary
(
    inlet
    {
        type patch;
        faces
        (
            (0 4 7 3)
        );
    }
    outlet
    {
        type patch;
        faces
        (
            (1 2 6 5)
        );
    }
    Wall
    {
        type wall;
        faces
        (
            (0 1 2 3)
            (4 5 6 7)
            (3 2 6 7)
            (0 1 5 4)
        );
    }
);

mergePatchPairs
(
);

// ************************************************************************* //
When i run blockMesh with this vertices, i get the error massage:
Code:
Checking geometry...
    Overall domain bounding box (0 0 0) (0.1 0.08 0.02)
    Mesh (non-empty, non-wedge) directions (1 1 1)
    Mesh (non-empty) directions (1 1 1)
    Boundary openness (5.08774e-17 -1.73343e-16 -2.05592e-16) OK.
 ***High aspect ratio cells found, Max aspect ratio: 2.76503e+194, number of cells 6000
  <<Writing 6000 cells with high aspect ratio to set highAspectRatioCells
    Minimum face area = 8.95863e-07. Maximum face area = 6.3631e-06.  Face area magnitudes OK.
    Min volume = 2e-300. Max volume = 2e-300.  Total volume = 1.2e-296.  Cell volumes OK.
    Mesh non-orthogonality Max: 180 average: 157.305
 ***Number of non-orthogonality errors: 16850.
  <<Writing 16850 non-orthogonal faces to set nonOrthoFaces
 ***Error in face pyramids: 36000 faces are incorrectly oriented.
  <<Writing 19150 faces with incorrect orientation to set wrongOrientedFaces
    Max skewness = 3.57447 OK.
    Coupled point location match (average 0) OK.

Failed 3 mesh checks.

End

But when i change the vertices(while the geometry remain approximately constant), like this :
vertices
(
(-5 4 0) //0
(0 -1 0) //1
(0 0.5 0.5) //2
(-4 4 0) //3
(-5 4 2) //4
(0 -1 0.5) //5
(0 0.5 1) //6
(-4 4 2) //7
);

everything is ok. I'm confused. I don't know how i solve this problem. Do you know how solve this problem?
Thank you very much for your help.




Best regards,
Ali
Alih is offline   Reply With Quote

Reply

Thread Tools
Display Modes

Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is Off
Trackbacks are On
Pingbacks are On
Refbacks are On


Similar Threads
Thread Thread Starter Forum Replies Last Post
Errors in UDF shashank312 Fluent UDF and Scheme Programming 6 May 30, 2013 20:30
Ansys Fluent 13.0 UDF compilation problem in Window XP (32 bit) Yogini Fluent UDF and Scheme Programming 7 October 3, 2012 07:24
c++ libraries and solver compiling vaina74 OpenFOAM Installation 13 February 3, 2012 18:43
POSDAT problem piotka STAR-CD 4 June 12, 2009 08:43
Problem with compile the setParabolicInlet ivanyao OpenFOAM Running, Solving & CFD 6 September 5, 2008 20:50


All times are GMT -4. The time now is 08:06.