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Old   May 23, 2013, 10:57
Default mesh comparative
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Mizo
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Hello every one

I have a question:

I generated 2 meshs for the same case (one with Star ccm+ und the another with OpenFoam), although I sat the same refinement levels for both, I got a difference number of cells (the mesh with Starccm+ generated 28 % more cells than with Openfoam)

does any one now, where the problem is?

is there any method to generate the same number of cells??

Thanx in advance

my best regards to all

Mizo

Last edited by Ingenieur; May 28, 2013 at 04:20.
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Old   May 24, 2013, 09:39
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Hi Monzer,


How complex is the mesh? I mean, is it simply a box or do you have object in their etc. Cause if both tools use different algorithms to handle the 'obstructions' this could easily lead to different meshes.

Cheers,

Lieven
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Old   May 26, 2013, 07:43
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Hi Lieven,

thank you for your reply

the mesh is a box around a car, it's nearly 100 million cells, you are right, the both tools use different algorithms to handle the mesh, but how can I get (almost) the same number of cells with the same settings(level refinement... etc)

best regards,


Mizo

Last edited by Ingenieur; May 28, 2013 at 04:20.
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Old   May 26, 2013, 08:17
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Would importing the Star ccm+ mesh into OF solve the problem?
Cause a quick seach on google resulted in
http://openfoamwiki.net/index.php/Ccm26ToFoam
star-ccm mesh to O\/F

Then you have exactly the same number of cells ;-)

Cheers,

L
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Old   May 27, 2013, 03:13
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Hi Lieven,

do you know, how can I edit the shrinkDict under ($FOAM_ETC)
because the Dictionary is (read only)

best regards
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Old   May 27, 2013, 03:31
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Well, the answer is pretty straight forward. You should never edit anything under $FOAM_ETC so from that point of view it's a good thing it doesn't work ;-)

Best thing to do is to copy the file from $FOAM_ETC to the case you want to run it on.

Cheers,

Lieven
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Old   May 27, 2013, 03:45
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ok Lieven

I'll try it and then reply the resualt
thank you alot
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Old   May 28, 2013, 03:29
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Hi Lieven,

u r right, your suggestion worked very well
but I have another question about the layers.
fo u know the optimal value of (nGrow) to get a good layers everywhere??

thank you very much in advance

best regards
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Old   May 28, 2013, 03:50
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Hi Mizo,

I can't really help you with that. Maybe someone else can but then you will probably need to be more specific:
* which software package
* which geometry
* flow type
* ...

Cheers,

Lieven
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Old   May 28, 2013, 04:18
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Ok am using OpenFoam2.2.0

* germetry is a car
* the flow is turbulent (unsteady-les)

what I want actually is to get a good layer everywhere at the surface of the car

I tried with (nGrow=0) then (=1), the first one was pretty better
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