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-   -   How to change the turbulance model (http://www.cfd-online.com/Forums/openfoam-pre-processing/61993-how-change-turbulance-model.html)

sivakumar August 18, 2008 10:13

Hello, i am new to openfoam,
 
Hello, i am new to openfoam, i am doing simulation in aircraft cabin thermal comport.for this i am using K-epsilon turbulence model.
i want to change the turbulence model how can i change the turbulence model? can anyone help me?



sivakumar

grtabor August 18, 2008 10:46

Look for a file in the directo
 
Look for a file in the directory "constant" called "turbulenceProperties". This is called a dictionary file and contains the information you need to run turbulent simulations. (Dictionaries are used extensively in OpenFOAM for controlling the code). After the header (lots of commented lines) and the FoamFile entry there should be a line

turbulenceModel kEpsilon;

turbulence on;

which specifies you are running the k-e model (and it is switched on). If you change this to (say) kOmegaSST it will change the model used. The rest of the file contains entries - more dictionaries in fact - containing the coefficients for the model (entry for model X is XCoeffs)

Gavin

sivakumar August 18, 2008 11:33

hello thank you for u r replay
 
hello thank you for u r replay,
actually i tried but i am unable to see the turbulence properties in this file.
i am able to see "polymesh" and "transportproperties" only these two nothing else

ivanwhlau August 18, 2008 20:56

I think you are using OF-1.5,
 
I think you are using OF-1.5, right?
Look for "RASProperties" in the "constant" directory instead.
Ivan

sivakumar August 19, 2008 03:06

hello, i got it, thank
 
hello,
i got it, thank you. i have one more question
do we need to change all the entries?

ivanwhlau August 19, 2008 04:09

I think you only need to chang
 
I think you only need to change the RASModel

sivakumar August 19, 2008 05:03

i changed only RASModel but it
 
i changed only RASModel but its giving Following Error

Selecting incompressible transport model Newtonian
Selecting RAS turbulence model kOmegaSST


cannot open file

file: /home/junkers/selv_si/OpenFOAM1.5/selv_si-1.5/run/tutorials/simpleFoam/kabineKOm egaSST/2000/omega at line 0.

From function regIOobject::readStream(const word&)
in file db/regIOobject/regIOobjectRead.C at line 66.

FOAM exiting

grtabor August 19, 2008 06:45

The k-omega model needs a fiel
 
The k-omega model needs a field called omega to start from - you will need to generate this somehow. This is what the error message is telling you. The easiest approach would probably be to take the epsilon field file, rename it to omega and change its dimensions.

Sorry for the earlier confusion - I'm still using 1.4.1 not 1.5 (must upgrade).

Gavin

sivakumar August 19, 2008 07:47

ya thank you man it is working
 
ya thank you man it is working now

naveen February 17, 2009 06:56

hi sivakumar selvaraju sir
 
hi sivakumar selvaraju sir

i am from india...i am trying to solve naca 0012(c-grid) airfoil case in openfoam 1.4.1....can u tell me how to solve by giving various conditions like lift,drag,velocity,pressure & tell me where to give these conditions...if ur having procedure to solve this case please send me the procedure..


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