Meshing an axissymetric 2D case - Problems

Andyjoe · January 27, 2010, 13:31

Hello,
This day and the half of last night I spend trying to mesh an axissymetrc 2D case.
First I made a box, which was the "windtunnel". Two sites were wedges, I did it like in the OpenFOAM documentation. Then I inserted a box, which lines were polylines. Here the first problem occured. The interpolationpoints inserted had an x and y coordinate smaller than 4, but some of the mesh points had coordinates with values above 300. The convertToMeters was set to 1. So the mesh doesn't look good when I loaded it in Paraview.
I tryed simpleSpline etc. too, but then blockMesh crashed.
Then I decided to use only arcs and boxes. The mesh looked good then, but it has too much cells in z-direction. For both boxes I set the cell number in z direction to 1, but this advice seems to be ignored.
My next test was to make only one channel. The y coordinate of the ground of this tunnel follows the geometry of the simulated body. Then blockMesh always crashes, without given an error, it just tells the lines, in which the libs are crashed.
So my question is, how it is possible to create an axissymetric 2D case. It would be easy for me, if there is a possibility to use polyLines etc, because I can calculate the test objects with functions, which enables me to get Points. Furthermore I would be interested in how stable blockMesh is or if anyone knows Bugs in it.
Thank you in advertise for any answer

Andyjoe · January 27, 2010, 15:11

The last hours I kept on trying. Now I've got a concrete error message. First of all, here my blockMeshDict:

Code:

 FoamFile
 {                             
     version     2.0;          
     format      ascii;        
     class       dictionary;   
     object      blockMeshDict;
 }                             
convertToMeters 1;         
vertices                       
(
                            
(0 0 0)
(0.6 0.125 0)
(0.6  0.125 0.0108) 
(0  0 0) 
(0 1 0) 
(0.6 1 0) 
(0.6 1 0.087) 
(0 1 0.087) 

(0.6 0.125 0)
(0.91 0.125 0)
(0.91 0.125 0.0108)
(0.6 0.125 0.0108) 
(0.6 1 0) 
(0.91 1 0) 
(0.91 1 0.087) 
(0.6 1 0.087) 

(0.91 0.125 0)
(1.91 0.45 0)
(1.91 0.45 0.039)
(0.91 0.125 0.0108)
(0.91 1 0) 
(1.91 1 0) 
(1.91 1 0.087) 
(0.91 1 0.087)

(1.91 0.45 0)
(2.37 0 0)
(2.37  0 0) 
(1.91  0.45 0.0108) 
(1.91 1 0) 
(2.37 1 0) 
(2.37 1 0.087) 
(1.91 1 0.087)
);
blocks
(
hex (0 1 2 0 4 5 6 7) (200 200 1) simpleGrading (1 1 1) //windtunnel 
hex (1 9 10 3 6 13 14 7) (100 100 1) simpleGrading (1 1 1) // tail block 
hex (9 17 18 10 13 21 22 14) (200 150 1) simpleGrading (1 1 1) // tail block
hex (17 26 26 18 21 29 30 22 ) (250 150 1) simpleGrading (1 1 1) // tail block 

);
edges
(
arc 1 2 (0.2 0.098 0)
arc 3 4 (0.2 0.098 0.008526)
arc 17 26 (2.23 0.387 0)
arc 18 26 (2.23 0.387 0.0067338)
);
patches         
(
patch inlet
(
(0 4 7 0)
)
patch outlet
(
(26 30 29 26)
)
patch top
(
(5 6 7 4)
(5 13 14 6)
(14 22 21 13)
(22 29 30 21)
)
patch phoenix
(
(0 2 1 0)
(1 2 10 9)
(10 18 17 9)
(18 26 25 17)
)
 wedge frontback
(
(0 1 5 4)
(0 7 6 2)

(2 6 22 18)
(1 9 13 5)

(9 17 21 13)
(10 14 21 17)

(16 25 29 20)
(17 21 30 26)
)
);
mergePatchpairs 
(
);

Not every point defined is used. The reason is, that it makes counting easier for me. For example I know, that the secound box has the vertices 16-23.
The important line of the error message is:

Code:

face 1 in patch 1 does not have neighbour cell face: 4(5 13 14 6)#0

Googling this errormessage gave one result. There the error was in mergePatchpairs. I've already got this message too, I solved the problem by inverting the order of the vertices in the brackets. So I guess this errormessage can have several reasons. But I don't know where to look anymore. I think the vertices are in the correct order, and changing the order doesn't change anything at the message.
Could anyone assume, where the mistake could be, or has anyone experience with this errormassage?

JinBiao · January 27, 2010, 21:56

Hi, Andreas

I am also trying to do a 2D axis-symmetrical mesh. The last error you have may be caused by a wrong ordering of the vertices when you define the hexes or patches. Actually I had exact same error. And I eliminated it by re-order the vertices.

Here I have another problem. I always got an failure when I do checkMesh.

Quote:

***Number of edges not aligned with or perpendicular to non-empty directions: 11438
<<Writing 11739 points on non-aligned edges to set nonAlignedEdges

This failure even occur when I run the example provided in the openfoamwiki for 2D axis-symmetric case. Does anyone have an idea why this happens?

Regards

Jinbiao

Andyjoe · January 28, 2010, 08:29

Hi Jinbiao,

have you tried to look at your mesh with paraView? This often helps to spot the point, where the mesh is bad, whereas checkMesh just tells you numbers.

Andyjoe · January 28, 2010, 15:44

I kept on trying. Now paraview shows a mesh which seems to be ok. Theoretically this can be applied to any 2D Body which can be described as a function. Scince the body is symmetric, I only simulate the upper half. But with the polylines not use, the surface at the bottom can be also described.

Code:

 FoamFile
 {                             
     version     2.0;          
     format      ascii;        
     class       dictionary;   
     object      blockMeshDict;
 }                             
convertToMeters 1;         
vertices                       
(                            
(2.37 0 0.000000)
(1.92 0.45 0.000000)
(0 0 0)
(0.6 0.125 0.000000)
(0.1 0 0.000000)
(2.37 0 0.100000)
(1.92 0.45 0.100000)
(0.1 0 0)
(0.6 0.125 0.100000)
(0.1 0 0.1)
( 2.500000  1.000000 0) 
(-0.000000  1.000000 0) 
(-0.000000 -0.000000 0) 
( 2.500000 -0.000000 0) 
( 2.500000  1.000000 .1)
(-0.000000  1.000000 .1)
(-0.000000 -0.000000 .1)
( 2.500000 -0.000000 .1)
);
blocks
(
hex (1 0 10 11 6 5 14 15) (100 100 1) simpleGrading (1 1000 1) //rear  
hex (0 4 13 10 5 9 17 14) (100 100 1) simpleGrading (1 1000 1) // middle 
hex (4 3 12 13 9 8 16 17) (100 100 1) simpleGrading (1 1000 1) // else
hex (3 1 11 12 8 6 15 16) (100 100 1) simpleGrading (1 1000 1) // front
);
edges
(
line 10 11 
line 14 15 
line 11 12 
line 15 16 
line 12 13 
line 16 17 
line 13 10 
line 17 14 
line 10 11 
line 14 15 
line 11 12 
line 15 16 
line 12 13 
line 16 17 
line 13 10 
line 17 14 
polyLine 0 1 (
(    2.33    0.18547    0    )
(    2.21    0.34409    0    )
(    2.15    0.38678    0    )
(    2.08    0.42059    0    )
(    2.06    0.42767    0    )
(    2.04    0.4337    0    )
(    2.02    0.43875    0    )
(    2    0.44283    0    )
(    1.98    0.44598    0    )
(    1.96    0.44822    0    )
(    1.94    0.44956    0    )

/*(1.92    0.45    0)
(1.93    0.44989    0)
(1.94    0.44956    0)
(1.95    449    0)
(1.96    0.44822    0)
(1.97    0.44721    0)
(1.98    0.44598    0)
(1.99    0.44452    0)
(2    0.44283    0)
(2.01    0.44091    0)
(2.02    0.43875    0)
(2.03    0.43635    0)
(2.04    0.4337    0)
(2.05    0.43081    0)
(2.06    0.42767    0)
(2.07    0.42426    0)
(2.08    0.42059    0)
(2.09    0.41665    0)
(2.1    0.41243    0)
(2.11    0.40792    0)
(2.12    0.40311    0)
(2.13    0.39799    0)
(2.14    0.39256    0)
(2.15    0.38678    0)
(2.16    0.38066    0)
(2.17    0.37417    0)
(2.18    0.36729    0)
(2.19    0.36    0)
(2.2    0.35228    0)
(2.21    0.34409    0)
(2.22    0.33541    0)
(2.23    0.32619    0)
(2.24    0.31639    0)
(2.25    0.30594    0)
(2.26    0.29479    0)
(2.27    0.28284    0)
(2.28    0.27    0)
(2.29    0.25612    0)
(2.3    0.24104    0)
(2.31    0.2245    0)
(2.32    0.20616    0)
(2.33    0.18547    0)
(2.34    0.16155    0)
(2.35    0.13266    0)
(2.36    0.09434    0)
(2.37    0    0)*/
)

polyLine 5 6 (
(    2.33    0.18547    0.1    )
(    2.21    0.34409    0.1    )
(    2.15    0.38678    0.1    )
(    2.08    0.42059    0.1    )
(    2.06    0.42767    0.1    )
(    2.04    0.4337    0.1    )
(    2.02    0.43875    0.1    )
(    2    0.44283    0.1    )
(    1.98    0.44598    0.1    )
(    1.96    0.44822    0.1    )
(    1.94    0.44956    0.1    )

/*(1.92    0.45    0.1)
(1.93    0.44989    0.1)
(1.94    0.44956    0.1)
(1.95    449    0.1)
/*(1.96    0.44822    0.1)
(1.97    0.44721    0.1)
(1.98    0.44598    0.1)
(1.99    0.44452    0.1)
(2    0.44283    0.1)
(2.01    0.44091    0.1)
(2.02    0.43875    0.1)
(2.03    0.43635    0.1)
(2.04    0.4337    0.1)
(2.05    0.43081    0.1)
(2.06    0.42767    0.1)
(2.07    0.42426    0.1)
(2.08    0.42059    0.1)
(2.09    0.41665    0.1)
(2.1    0.41243    0.1)
(2.11    0.40792    0.1)
(2.12    0.40311    0.1)
(2.13    0.39799    0.1)
(2.14    0.39256    0.1)
(2.15    0.38678    0.1)
(2.16    0.38066    0.1)
(2.17    0.37417    0.1)
(2.18    0.36729    0.1)
(2.19    0.36    0.1)
(2.2    0.35228    0.1)
(2.21    0.34409    0.1)
(2.22    0.33541    0.1)
(2.23    0.32619    0.1)
(2.24    0.31639    0.1)
(2.25    0.30594    0.1)
(2.26    0.29479    0.1)
(2.27    0.28284    0.1)
(2.28    0.27    0.1)
(2.29    0.25612    0.1)
(2.3    0.24104    0.1)
(2.31    0.2245    0.1)
(2.32    0.20616    0.1)
(2.33    0.18547    0.1)
(2.34    0.16155    0.1)
(2.35    0.13266    0.1)
(2.36    0.09434    0.1)
(2.37    0    0.1)*/
)
/*polyLine 1 3 (
(    1.87    0.43375    0    )
(    1.53    0.32325    0    )
(    1.46    0.3005    0    )
(    1.41    0.28425    0    )
(    1.02    0.1575    0    )
(    0.96    138    0    )
(    0.92    125    0    )
(    0.73    125    0    )
(    0.7    125    0    )

)
polyLine 6 8 (
(    1.87    0.43375    0.1    )
(    1.53    0.32325    0.1    )
(    1.46    0.3005    0.1    )
(    1.41    0.28425    0.1    )
(    1.02    0.1575    0.1    )
(    0.96    138    0.1    )
(    0.92    125    0.1    )
(    0.73    125    0.1    )
(    0.7    125    0.1    )

)*/
/*polyLine 3 4 (
(nan 0.000000 0.000000)
)
polyLine 8 9 (
(nan 0.000000 0.100000)
)*/
);
patches (
wall phoenix
(
(0 1 6 5)
(1 3 8 6)
(3 4 9 8)
(4 0 5 9)
)
patch inlet
(
(11 12 16 15)
)
patch outlet
(
(13 10 14 17)
)
patch top
(
(10 11 15 14)
)
patch bottom
(
(12 13 17 16)
)
empty frontback
(
(1 0 10 11)
(3 1 11 12)
(4 3 12 13)
(0 4 13 10)
(6 5 14 15)
(8 6 15 16)
(9 8 16 17)
(5 9 17 14)
)
);
mergePatchpairs ();

Then the phoenix looks like in the first pictuere phoenix2Da, without the frontback surfaces. Every patch is where it should be. But when I apply the temporary phoenix.OpenFoam, an additional surface appears. I dont know where this surface comes from. Maybe a bug in paraFoam, because when I'm using foamToVTK and load every patch patch after patch, I got what I want to.
But with simple increasing the number of points, I got the strange result described above, with very long lines up to coordinates above 100 (picture phoenix2Dc). Is this a bug? Here the changed lines oft my blockMeshDict

Code:

polyLine 0 1 (
(    2.36    0.09434    0    )
(    2.35    0.13266    0    )
(    2.34    0.16155    0    )
(    2.33    0.18547    0    )
(    2.32    0.20616    0    )
(    2.31    0.2245    0    )
(    2.3    0.24104    0    )
(    2.29    0.25612    0    )
(    2.28    0.27    0    )
(    2.27    0.28284    0    )
(    2.26    0.29479    0    )
(    2.25    0.30594    0    )
(    2.24    0.31639    0    )
(    2.23    0.32619    0    )
(    2.22    0.33541    0    )
(    2.21    0.34409    0    )
(    2.2    0.35228    0    )
(    2.19    0.36    0    )
(    2.18    0.36729    0    )
(    2.17    0.37417    0    )
(    2.16    0.38066    0    )
(    2.15    0.38678    0    )
(    2.14    0.39256    0    )
(    2.13    0.39799    0    )
(    2.12    0.40311    0    )
(    2.11    0.40792    0    )
(    2.1    0.41243    0    )
(    2.09    0.41665    0    )
(    2.08    0.42059    0    )
(    2.07    0.42426    0    )
(    2.06    0.42767    0    )
(    2.05    0.43081    0    )
(    2.04    0.4337    0    )
(    2.03    0.43635    0    )
(    2.02    0.43875    0    )
(    2.01    0.44091    0    )
(    2    0.44283    0    )
(    1.99    0.44452    0    )
(    1.98    0.44598    0    )
(    1.97    0.44721    0    )
(    1.96    0.44822    0    )
(    1.95    449    0    )
(    1.94    0.44956    0    )
(    1.93    0.44989    0    )
(    2.36    0.09434    0    )
(    2.35    0.13266    0    )
(    2.34    0.16155    0    )
(    2.33    0.18547    0    )
(    2.32    0.20616    0    )
(    2.31    0.2245    0    )
(    2.3    0.24104    0    )
(    2.29    0.25612    0    )
(    2.28    0.27    0    )
(    2.27    0.28284    0    )
(    2.26    0.29479    0    )
(    2.25    0.30594    0    )
(    2.24    0.31639    0    )
(    2.23    0.32619    0    )
(    2.22    0.33541    0    )
(    2.21    0.34409    0    )
(    2.2    0.35228    0    )
(    2.19    0.36    0    )
(    2.18    0.36729    0    )
(    2.17    0.37417    0    )
(    2.16    0.38066    0    )
(    2.15    0.38678    0    )
(    2.14    0.39256    0    )
(    2.13    0.39799    0    )
(    2.12    0.40311    0    )
(    2.11    0.40792    0    )
(    2.1    0.41243    0    )
(    2.09    0.41665    0    )
(    2.08    0.42059    0    )
(    2.07    0.42426    0    )
(    2.06    0.42767    0    )
(    2.05    0.43081    0    )
(    2.04    0.4337    0    )
(    2.03    0.43635    0    )
(    2.02    0.43875    0    )
(    2.01    0.44091    0    )
(    2    0.44283    0    )
(    1.99    0.44452    0    )
(    1.98    0.44598    0    )
(    1.97    0.44721    0    )
(    1.96    0.44822    0    )
(    1.95    449    0    )
(    1.94    0.44956    0    )
(    1.93    0.44989    0    )


/*(1.92    0.45    0)
(1.93    0.44989    0)
(1.94    0.44956    0)
(1.95    449    0)
(1.96    0.44822    0)
(1.97    0.44721    0)
(1.98    0.44598    0)
(1.99    0.44452    0)
(2    0.44283    0)
(2.01    0.44091    0)
(2.02    0.43875    0)
(2.03    0.43635    0)
(2.04    0.4337    0)
(2.05    0.43081    0)
(2.06    0.42767    0)
(2.07    0.42426    0)
(2.08    0.42059    0)
(2.09    0.41665    0)
(2.1    0.41243    0)
(2.11    0.40792    0)
(2.12    0.40311    0)
(2.13    0.39799    0)
(2.14    0.39256    0)
(2.15    0.38678    0)
(2.16    0.38066    0)
(2.17    0.37417    0)
(2.18    0.36729    0)
(2.19    0.36    0)
(2.2    0.35228    0)
(2.21    0.34409    0)
(2.22    0.33541    0)
(2.23    0.32619    0)
(2.24    0.31639    0)
(2.25    0.30594    0)
(2.26    0.29479    0)
(2.27    0.28284    0)
(2.28    0.27    0)
(2.29    0.25612    0)
(2.3    0.24104    0)
(2.31    0.2245    0)
(2.32    0.20616    0)
(2.33    0.18547    0)
(2.34    0.16155    0)
(2.35    0.13266    0)
(2.36    0.09434    0)
(2.37    0    0)*/
)

polyLine 5 6 (
(    2.37    0    0.1    )
(    2.36    0.09434    0.1    )
(    2.35    0.13266    0.1    )
(    2.34    0.16155    0.1    )
(    2.33    0.18547    0.1    )
(    2.32    0.20616    0.1    )
(    2.31    0.2245    0.1    )
(    2.3    0.24104    0.1    )
(    2.29    0.25612    0.1    )
(    2.28    0.27    0.1    )
(    2.27    0.28284    0.1    )
(    2.26    0.29479    0.1    )
(    2.25    0.30594    0.1    )
(    2.24    0.31639    0.1    )
(    2.23    0.32619    0.1    )
(    2.22    0.33541    0.1    )
(    2.21    0.34409    0.1    )
(    2.2    0.35228    0.1    )
(    2.19    0.36    0.1    )
(    2.18    0.36729    0.1    )
(    2.17    0.37417    0.1    )
(    2.16    0.38066    0.1    )
(    2.15    0.38678    0.1    )
(    2.14    0.39256    0.1    )
(    2.13    0.39799    0.1    )
(    2.12    0.40311    0.1    )
(    2.11    0.40792    0.1    )
(    2.1    0.41243    0.1    )
(    2.09    0.41665    0.1    )
(    2.08    0.42059    0.1    )
(    2.07    0.42426    0.1    )
(    2.06    0.42767    0.1    )
(    2.05    0.43081    0.1    )
(    2.04    0.4337    0.1    )
(    2.03    0.43635    0.1    )
(    2.02    0.43875    0.1    )
(    2.01    0.44091    0.1    )
(    2    0.44283    0.1    )
(    1.99    0.44452    0.1    )
(    1.98    0.44598    0.1    )
(    1.97    0.44721    0.1    )
(    1.96    0.44822    0.1    )
(    1.95    449    0.1    )
(    1.94    0.44956    0.1    )
(    1.93    0.44989    0.1    )

/*(1.92    0.45    0.1)
(1.93    0.44989    0.1)
(1.94    0.44956    0.1)
(1.95    449    0.1)
/*(1.96    0.44822    0.1)
(1.97    0.44721    0.1)
(1.98    0.44598    0.1)
(1.99    0.44452    0.1)
(2    0.44283    0.1)
(2.01    0.44091    0.1)
(2.02    0.43875    0.1)
(2.03    0.43635    0.1)
(2.04    0.4337    0.1)
(2.05    0.43081    0.1)
(2.06    0.42767    0.1)
(2.07    0.42426    0.1)
(2.08    0.42059    0.1)
(2.09    0.41665    0.1)
(2.1    0.41243    0.1)
(2.11    0.40792    0.1)
(2.12    0.40311    0.1)
(2.13    0.39799    0.1)
(2.14    0.39256    0.1)
(2.15    0.38678    0.1)
(2.16    0.38066    0.1)
(2.17    0.37417    0.1)
(2.18    0.36729    0.1)
(2.19    0.36    0.1)
(2.2    0.35228    0.1)
(2.21    0.34409    0.1)
(2.22    0.33541    0.1)
(2.23    0.32619    0.1)
(2.24    0.31639    0.1)
(2.25    0.30594    0.1)
(2.26    0.29479    0.1)
(2.27    0.28284    0.1)
(2.28    0.27    0.1)
(2.29    0.25612    0.1)
(2.3    0.24104    0.1)
(2.31    0.2245    0.1)
(2.32    0.20616    0.1)
(2.33    0.18547    0.1)
(2.34    0.16155    0.1)
(2.35    0.13266    0.1)
(2.36    0.09434    0.1)
(2.37    0    0.1)*/
)

perhaps I made an mistake, but I don't find it.

Andyjoe · January 28, 2010, 15:50

Now the big problem. SonicFoam doesn't work, even in the case which is meshed like I wanted it to. It gives the following errormessage

Code:

Starting time loop

Time = 1e-05

Courant Number mean: 22.7905 max: 3235.72
diagonal:  Solving for rho, Initial residual = 0, Final residual = 0, No Iterations 0
#0  Foam::error::printStack(Foam::Ostream&) in "/home/andreas/OpenFOAM/OpenFOAM-1.6/lib/linux64GccDPOpt/libOpenFOAM.so"
#1  Foam::sigFpe::sigFpeHandler(int) in "/home/andreas/OpenFOAM/OpenFOAM-1.6/lib/linux64GccDPOpt/libOpenFOAM.so"
#2  ?? in "/lib/libc.so.6"
#3  void Foam::fvc::surfaceIntegrate<Foam::Vector<double> >(Foam::Field<Foam::Vector<double> >&, Foam::GeometricField<Foam::Vector<double>, Foam::fvsPatchField, Foam::surfaceMesh> const&) in "/home/andreas/OpenFOAM/OpenFOAM-1.6/lib/linux64GccDPOpt/libfiniteVolume.so"
#4  Foam::tmp<Foam::GeometricField<Foam::Vector<double>, Foam::fvPatchField, Foam::volMesh> > Foam::fvc::surfaceIntegrate<Foam::Vector<double> >(Foam::GeometricField<Foam::Vector<double>, Foam::fvsPatchField, Foam::surfaceMesh> const&) in "/home/andreas/OpenFOAM/OpenFOAM-1.6/lib/linux64GccDPOpt/libfiniteVolume.so"
#5  Foam::tmp<Foam::GeometricField<Foam::Vector<double>, Foam::fvPatchField, Foam::volMesh> > Foam::fvc::surfaceIntegrate<Foam::Vector<double> >(Foam::tmp<Foam::GeometricField<Foam::Vector<double>, Foam::fvsPatchField, Foam::surfaceMesh> > const&) in "/home/andreas/OpenFOAM/OpenFOAM-1.6/lib/linux64GccDPOpt/libfiniteVolume.so"
#6  Foam::fv::gaussDivScheme<Foam::Tensor<double> >::fvcDiv(Foam::GeometricField<Foam::Tensor<double>, Foam::fvPatchField, Foam::volMesh> const&) in "/home/andreas/OpenFOAM/OpenFOAM-1.6/lib/linux64GccDPOpt/libfiniteVolume.so"
#7  Foam::tmp<Foam::GeometricField<Foam::innerProduct<Foam::Vector<double>, Foam::Tensor<double> >::type, Foam::fvPatchField, Foam::volMesh> > Foam::fvc::div<Foam::Tensor<double> >(Foam::GeometricField<Foam::Tensor<double>, Foam::fvPatchField, Foam::volMesh> const&, Foam::word const&) in "/home/andreas/OpenFOAM/OpenFOAM-1.6/lib/linux64GccDPOpt/libcompressibleRASModels.so"
#8  Foam::tmp<Foam::GeometricField<Foam::innerProduct<Foam::Vector<double>, Foam::Tensor<double> >::type, Foam::fvPatchField, Foam::volMesh> > Foam::fvc::div<Foam::Tensor<double> >(Foam::GeometricField<Foam::Tensor<double>, Foam::fvPatchField, Foam::volMesh> const&) in "/home/andreas/OpenFOAM/OpenFOAM-1.6/lib/linux64GccDPOpt/libcompressibleRASModels.so"
#9  Foam::compressible::RASModels::LaunderSharmaKE::divDevRhoReff(Foam::GeometricField<Foam::Vector<double>, Foam::fvPatchField, Foam::volMesh>&) const in "/home/andreas/OpenFOAM/OpenFOAM-1.6/lib/linux64GccDPOpt/libcompressibleRASModels.so"
#10  main in "/home/andreas/OpenFOAM/OpenFOAM-1.6/applications/bin/linux64GccDPOpt/sonicFoam"
#11  __libc_start_main in "/lib/libc.so.6"
#12  _start at /usr/src/packages/BUILD/glibc-2.9/csu/../sysdeps/x86_64/elf/start.S:116
Floating point exception

seems to be a little cryptic to me, but I assume that it is due to the mesh. So I run checkMesh

Code:

Create polyMesh for time = 0

Time = 0

Mesh stats
    points:           80800
    internal points:  0
    faces:            160400
    internal faces:   79600
    cells:            40000
    boundary patches: 6
    point zones:      0
    face zones:       0
    cell zones:       0

Overall number of cells of each type:
    hexahedra:     40000
    prisms:        0
    wedges:        0
    pyramids:      0
    tet wedges:    0
    tetrahedra:    0
    polyhedra:     0

Checking topology...
    Boundary definition OK.
    Point usage OK.
    Upper triangular ordering OK.
    Face vertices OK.
    Number of regions: 1 (OK).

Checking patch topology for multiply connected surfaces ...
    Patch               Faces    Points   Surface topology                  
    phoenix             400      800      ok (non-closed singly connected)  
    inlet               100      202      ok (non-closed singly connected)  
    outlet              100      202      ok (non-closed singly connected)  
    top                 100      202      ok (non-closed singly connected)  
    bottom              100      202      ok (non-closed singly connected)  
    frontback           80000    80800    ok (non-closed singly connected)  

Checking geometry...
    Overall domain bounding box (0 0 0) (2.5 1 0.1)
    Mesh (non-empty, non-wedge) directions (1 1 0)
    Mesh (non-empty) directions (1 1 0)
    All edges aligned with or perpendicular to non-empty directions.
    Boundary openness (-6.09642e-18 -1.90675e-17 -4.10049e-16) OK.
 ***High aspect ratio cells found, Max aspect ratio: 3.62059e+197, number of cells 24064
  <<Writing 24064 cells with high aspect ratio to set highAspectRatioCells
    Minumum face area = 3.7867e-11. Maximum face area = 0.0161903.  Face area magnitudes OK.
    Min volume = 2e-300. Max volume = 0.000162921.  Total volume = 0.234227.  Cell volumes OK.
    Mesh non-orthogonality Max: 179.936 average: 89.7278
   *Number of severely non-orthogonal faces: 18835.
 ***Number of non-orthogonality errors: 39972.
  <<Writing 58807 non-orthogonal faces to set nonOrthoFaces
 ***Error in face pyramids: 120186 faces are incorrectly oriented.
  <<Writing 80519 faces with incorrect orientation to set wrongOrientedFaces
 ***Max skewness = 8249.46, 270 highly skew faces detected which may impair the quality of the results
  <<Writing 270 skew faces to set skewFaces

Failed 4 mesh checks.

End

I don't know how it is possible to fix this error.

JinBiao · January 28, 2010, 20:29

Quote:

Originally Posted by Andyjoe

Hi Jinbiao,

have you tried to look at your mesh with paraView? This often helps to spot the point, where the mesh is bad, whereas checkMesh just tells you numbers.

Hi Andreas,

Yes, I have tried to view the mesh with paraView. But the paraview doesnot work anyway. When I press "apply", the paraview just exited automatically. I donot know why.

But when I neglect the warning, just run the case. I can obtain the result. And I can view the result using paraView. This problem is very confusing. Do you have any idea?

Regards

Jinbiao

Ahmed · January 28, 2010, 20:44

Andreas Jörg
This is the first line of your error log
Courant Number mean: 22.7905 max: 3235.72

Look the definition of the Courant number and see how it could be knocked down to be less or equal to One

when you get time, read about the physical meaning of the Courant Number

Andyjoe · January 28, 2010, 21:06

Thank you, Ahmed, that could solve the Problem. So my time step is too big, or my meshside too small.
JinBiao: Are you satisfied with the result of the simulation? I think, if the error in blockMesh isn't fatal it still could leed to results. ParaView doesn't work very well on my linux PC too. Under windows its more stable, in my case. Have you tried, to convert the files first "foamToVTK", then starting paraview and now loading the VTK file? For some reason on my pc this works better than using "paraFoam".
So for me the remaining problems are why I cant define more points and how to do the wedge.

Andyjoe · January 28, 2010, 23:34

I decreased the time-step and the maximal Courant number was about 0.3, but the same error occured.

JinBiao · January 29, 2010, 02:37

Andreas, thanks for you reply. foamToVTK works for me.

I think in your case you may still have some problem in the mesh. If I am right, I notice that in the beginning you defined the wedges in one patch. It seems not a proper way to do so. Please try to define it separately.

I hope this helps.

Regards,

Jinbiao

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January 27, 2010, 13:31	Meshing an axissymetric 2D case - Problems	#1
Andyjoe New Member Andreas Jörg Join Date: Jan 2010 Posts: 20 Rep Power: 16	Hello, This day and the half of last night I spend trying to mesh an axissymetrc 2D case. First I made a box, which was the "windtunnel". Two sites were wedges, I did it like in the OpenFOAM documentation. Then I inserted a box, which lines were polylines. Here the first problem occured. The interpolationpoints inserted had an x and y coordinate smaller than 4, but some of the mesh points had coordinates with values above 300. The convertToMeters was set to 1. So the mesh doesn't look good when I loaded it in Paraview. I tryed simpleSpline etc. too, but then blockMesh crashed. Then I decided to use only arcs and boxes. The mesh looked good then, but it has too much cells in z-direction. For both boxes I set the cell number in z direction to 1, but this advice seems to be ignored. My next test was to make only one channel. The y coordinate of the ground of this tunnel follows the geometry of the simulated body. Then blockMesh always crashes, without given an error, it just tells the lines, in which the libs are crashed. So my question is, how it is possible to create an axissymetric 2D case. It would be easy for me, if there is a possibility to use polyLines etc, because I can calculate the test objects with functions, which enables me to get Points. Furthermore I would be interested in how stable blockMesh is or if anyone knows Bugs in it. Thank you in advertise for any answer

January 28, 2010, 08:29		#4
Andyjoe New Member Andreas Jörg Join Date: Jan 2010 Posts: 20 Rep Power: 16	Hi Jinbiao, have you tried to look at your mesh with paraView? This often helps to spot the point, where the mesh is bad, whereas checkMesh just tells you numbers.

January 28, 2010, 20:44		#8
Ahmed Senior Member Ahmed Join Date: Mar 2009 Location: NY Posts: 251 Rep Power: 18	Andreas Jörg This is the first line of your error log Courant Number mean: 22.7905 max: 3235.72 Look the definition of the Courant number and see how it could be knocked down to be less or equal to One when you get time, read about the physical meaning of the Courant Number

January 28, 2010, 21:06		#9
Andyjoe New Member Andreas Jörg Join Date: Jan 2010 Posts: 20 Rep Power: 16	Thank you, Ahmed, that could solve the Problem. So my time step is too big, or my meshside too small. JinBiao: Are you satisfied with the result of the simulation? I think, if the error in blockMesh isn't fatal it still could leed to results. ParaView doesn't work very well on my linux PC too. Under windows its more stable, in my case. Have you tried, to convert the files first "foamToVTK", then starting paraview and now loading the VTK file? For some reason on my pc this works better than using "paraFoam". So for me the remaining problems are why I cant define more points and how to do the wedge. Last edited by Andyjoe; January 28, 2010 at 21:34.

January 28, 2010, 23:34		#10
Andyjoe New Member Andreas Jörg Join Date: Jan 2010 Posts: 20 Rep Power: 16	I decreased the time-step and the maximal Courant number was about 0.3, but the same error occured.

January 29, 2010, 02:37		#11
JinBiao Member Jinbiao Xiong Join Date: Oct 2009 Location: China/Japan Posts: 50 Rep Power: 16	Andreas, thanks for you reply. foamToVTK works for me. I think in your case you may still have some problem in the mesh. If I am right, I notice that in the beginning you defined the wedges in one patch. It seems not a proper way to do so. Please try to define it separately. I hope this helps. Regards, Jinbiao