# Time Dependency/ Scale Mesh/ Wall Definition

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 July 1, 2010, 09:34 Time Dependency/ Scale Mesh/ Wall Definition #1 New Member   Robyn Join Date: Jun 2010 Posts: 14 Rep Power: 9 Hello, I am fairly new to OpenFoam and thus with that come many questions. In any cases with OpenFoam its dependent on the Courant Number. If I enter the controlDict you can define deltaT. Now my question is in regards to steady state cases. Is deltaT time dependent or time iteration dependent? If time dependent why? Next question: How do you scale the mesh? I have a .msh file created in Gambit (completed the fluentMeshToFoam) simple 2D case (channel flow, d=1m) I would like to scale my geometry but only in the x direction ie, change the diameter to 1 cm instead of 1 m. Is this possible in OpenFoam or does the geometry need to be changed in the originial Gambit file? Final Question: In the boundary field how do I know which wall is which? ie in the icoFoam/elbow case there is 2 walls defined (wall-8, wall-4).

 July 2, 2010, 04:46 ref. Scaling #2 New Member   Robert Langner Join Date: Dec 2009 Location: Freiburg, Germany Posts: 27 Rep Power: 9 Hi Robyn, this might solve your scaling problem: fluentMeshToFoam -case -scaling '( )' just scale x-Direction: '(0.01 1 1)'

 July 2, 2010, 05:13 #3 New Member   Robyn Join Date: Jun 2010 Posts: 14 Rep Power: 9 Thanks for the response! I'll test it out.

 July 2, 2010, 09:50 #4 Senior Member   Nima Samkhaniani Join Date: Sep 2009 Location: Tehran, Iran Posts: 1,237 Blog Entries: 1 Rep Power: 18 hi friend the correct form of scaling command is like below , if u have any hint which help me to have various scaling in different direction it can be helpful fluentMeshToFoam balbla.msh -scale 0.1 or fluentMeshToFoam balbla.msh -scale '0.1'

July 7, 2010, 04:21
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Quote:
 Originally Posted by nimasam hi friend the correct form of scaling command is like below , if u have any hint which help me to have various scaling in different direction it can be helpful fluentMeshToFoam balbla.msh -scale 0.1 or fluentMeshToFoam balbla.msh -scale '0.1'
Well, you can first import your fluentmesh:
Code:
`fluentMeshToFoam balbla.msh`
and then scale it using
Quote:
 transformPoint -scale '(0.001 1 0.1)'
in such a way that you can specify different scaling factor.

July 7, 2010, 04:23
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Quote:
 Originally Posted by robyn In any cases with OpenFoam its dependent on the Courant Number. If I enter the controlDict you can define deltaT. Now my question is in regards to steady state cases. Is deltaT time dependent or time iteration dependent? If time dependent why?
If you have a steady state case, deltaT is equal to the iteration number and it has no physical meaning. Also, Courant Number does not mean anything.

 July 7, 2010, 06:53 #7 New Member   Robyn Join Date: Jun 2010 Posts: 14 Rep Power: 9 Thank you!

July 7, 2010, 08:07
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Quote:
 Originally Posted by robyn Final Question: In the boundary field how do I know which wall is which? ie in the icoFoam/elbow case there is 2 walls defined (wall-8, wall-4).
in your case-folder you can type
foamToVTK

and then start paraFoam and then open "File/Open" the "VTK"-folder that has been created with foamToVTK. there you can open the main body and the patches, so you can see what is what, by clicking on the "eye" next to the patch name or main body.

regards

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