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-   OpenFOAM Native Meshers: blockMesh (https://www.cfd-online.com/Forums/openfoam-meshing-blockmesh/)

 hartinger April 12, 2005 07:55

Hi everybody, i've written

Hi everybody,

i've written a calculator for the grading in the blockMesh format some time ago. It relates length, number of cells, total expansion ration, cell-to-cell expansion ratio, start cell size and end cell size.
Given the length and any two of the other, the remaining values are calculated.

It's a little programm, but I found it myself useful generating meshes with blockMesh.
If someone improves it, let me know

http://www.cfd-online.com/OpenFOAM_D...hment_icon.gif MeshSpace.tar.gz

regards
Markus

 hjasak April 12, 2005 09:36

Actually, the grading factor in blockMesh is defined as the ratio of the last to first cell size, which is much better behaved that defining the number of cells and the geometric expansion ratio. I suppose we have both done the same thing :-)

Hrv

 msrinath80 December 19, 2006 01:09

Hi Markus, Thanks for the u

Hi Markus,

Thanks for the utility. I found it very useful; esp. to find out the number of cells when one knows the start and end cell sizes in addition to the length.

I had to edit the Makefile to remove the reference to the bin subdirectory which does not exist. A sample of the utility usage is shown below for those who need to know how to use it:

madhavan@karmayug:~/MeshSpace$./MeshSpace ds de 0.58 0.000625 0.003125 Meshspace results by Markus.Hartinger@imperial.ac.uk : Length L : 0.58 Number of cells n : 373 Total expansion ratio r : 5 Cell-to-cell expansion k : 1.00434 Start cell size ds: 0.000625305 End cell size de: 0.00312652 madhavan@karmayug:~/MeshSpace$

 armin_h February 6, 2007 05:08

Hi Markus

i Couldent open that.

Cheers

 msrinath80 August 26, 2008 18:29

I get this error with gcc 4.3.

I get this error with gcc 4.3.1 when running make.

Any idea what is wrong?

g++ -g -c MeshSpace.cpp
MeshSpace.cpp: In function 'int main(int, char**)':
MeshSpace.cpp:35: error: 'exit' was not declared in this scope
MeshSpace.cpp:38: error: 'atof' was not declared in this scope
make: *** [MeshSpace.o] Error 1

 msrinath80 September 1, 2008 16:25

Problem solved. It was just a

Problem solved. It was just a question of adding:

#include <cstdlib>

to MeshSpace.cpp and TEdgeSpace.cpp

 83_Ale_83 July 21, 2010 09:36

Sorry, which is the problem??

5:45 ale@alien:~/MeshSpace\$ make
g++ -g -c MeshSpace.cpp
g++ -g -c TEdgeSpace.cpp
g++ -g -o bin/MeshSpace MeshSpace.o TEdgeSpace.o
/usr/bin/ld: cannot open output file bin/MeshSpace: No such file or directory
collect2: ld returned 1 exit status
make: *** [MeshSpace] Errore 1

 boger July 22, 2010 07:37

Quote:
 Originally Posted by 83_Ale_83 (Post 268336) Sorry, which is the problem??
If you read back a few posts, Srinath has already given the answer to this problem (and the next one you'll encounter). Delete bin/ from the Makefile, and include <cstdlib> in both .cpp files.

 83_Ale_83 July 22, 2010 08:04

Quote:
 Originally Posted by dab143psuedu (Post 268503) If you read back a few posts, Srinath has already given the answer to this problem (and the next one you'll encounter). Delete bin/ from the Makefile, and include in both .cpp files.
What a useless question I have done, I have missed the post
Thank you

 nileshjrane September 4, 2010 17:40

Stupid question..

How to give the arguments to the program??? I didnt get it..:(

Sorry for this stupid question.;)

 83_Ale_83 September 6, 2010 03:19

Quote:
 Originally Posted by nileshjrane (Post 274036) How to give the arguments to the program??? I didnt get it..:( Sorry for this stupid question.;)

Look at the third post; it's just an example;)

 nileshjrane September 6, 2010 05:44

Oh yes...i just overlooked it..i was trying meshspace value ds value de value...etc

 blaise December 22, 2010 06:02

Hi,

I cannot download the .tar.gz file. All I get is a short html file saying that the file I was looking for was not found on the server. This is saved with a .unk file extension. Using wget http://... brings the same result.

Can anybody shed some light on this? Or send me the file via email to pascal \at\ pascal-anschau \dot\ de?

Cheers, Pascal.

 la7low May 15, 2011 12:14

Quote:
 Originally Posted by armin_h (Post 206220) Hi Markus Would you please tel me how your calcualtor works? i Couldent open that. Cheers
I think it solves the equations I posted there: http://www.cfd-online.com/Forums/ans...tml#post307694

Just rename the downloaded file to "MeshSpace.tar.gz", extract it, then it should work.

 bigbang June 16, 2011 13:51

Quote:
 Originally Posted by boger (Post 268503) If you read back a few posts, Srinath has already given the answer to this problem (and the next one you'll encounter). Delete bin/ from the Makefile, and include in both .cpp files.
Thanks. This tools is just what I was looking for to mesh my boundary layer! Good show.

 prameelar August 17, 2011 12:31

Hi Srinath,

I am new to OpenFoam.
I need to create a mesh for channel with non linear mesh.
My node spacing is 12% increment for first 20 nodes near wall and 1.5 times viscous length scale and then 8% near the cwnter line and same on the otherside of the center line too..
I am confused how do I can take expansin ration?

Prameela.

 bigbang August 17, 2011 13:27

Hi Pam,

I would suggest first learning how to use blockMesh utility with openFOAM. You will need to separate the mesh into separate blocks for each grading.

First do a couple of the tutorials here to learn

Then use hartinger's tool to specify the grading based on your requirement.

Good luck.

 hhh February 27, 2012 05:01

Blockmesh

Dear Foamers,
i have xyz coordinates(that is model have 33 coumns and 225 rows in .csv file format) how i import and create blockmesh andbody have idea please let me know.

 Slackware_user April 8, 2012 09:32

first: are these coordinates of block vertices?
second: if so u can easyli write converter that will pull vertices of that file and create blocks, faces and edges.

if not that is not so easy.

Hint: remember that spline edges use mirror of last point for approxymation of y' in last point.

 hhh April 9, 2012 02:10

blockmesh-flapping wing

Dear Slackware_user,

first: these are the 3Dmodel coordinates generated in matlab,i have xyz coordinates of that model.for example generally people goes for cad model, same thing of that cad model but thing is i have coordinates, in matlab(that is model have 33 coumns and 225 rows xyz coordinates in .csv file format)how i can go for blockmesh.