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May 23, 2013, 10:57 |
mesh comparative
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#1 |
Member
Mizo
Join Date: Jan 2013
Posts: 34
Rep Power: 13 |
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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May 24, 2013, 09:39 |
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#2 |
Senior Member
Lieven
Join Date: Dec 2011
Location: Leuven, Belgium
Posts: 299
Rep Power: 22 |
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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May 26, 2013, 07:43 |
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#3 |
Member
Mizo
Join Date: Jan 2013
Posts: 34
Rep Power: 13 |
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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May 26, 2013, 08:17 |
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#4 |
Senior Member
Lieven
Join Date: Dec 2011
Location: Leuven, Belgium
Posts: 299
Rep Power: 22 |
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 http://www.cfd-online.com/Forums/ope...-mesh-o-f.html Then you have exactly the same number of cells ;-) Cheers, L |
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May 27, 2013, 03:13 |
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#5 |
Member
Mizo
Join Date: Jan 2013
Posts: 34
Rep Power: 13 |
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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May 27, 2013, 03:31 |
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#6 |
Senior Member
Lieven
Join Date: Dec 2011
Location: Leuven, Belgium
Posts: 299
Rep Power: 22 |
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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May 27, 2013, 03:45 |
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#7 |
Member
Mizo
Join Date: Jan 2013
Posts: 34
Rep Power: 13 |
ok Lieven
I'll try it and then reply the resualt thank you alot |
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May 28, 2013, 03:29 |
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#8 |
Member
Mizo
Join Date: Jan 2013
Posts: 34
Rep Power: 13 |
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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May 28, 2013, 03:50 |
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#9 |
Senior Member
Lieven
Join Date: Dec 2011
Location: Leuven, Belgium
Posts: 299
Rep Power: 22 |
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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May 28, 2013, 04:18 |
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#10 |
Member
Mizo
Join Date: Jan 2013
Posts: 34
Rep Power: 13 |
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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