k-omega in wingmotion tutorial

jlinterm · December 29, 2010, 08:33

Dear CFD-community,

I would like to understand the following piece of code in the wingMotion-tutorial with pimpleDyMFoam-solver. In the 0/omega-file it states:

Code:

wing
    {
        type            omegaWallFunction;
        Cmu             0.09;
        kappa           0.41;
        E                 9.8;
        beta1           0.075;
        value           uniform 32;
   }

How can I calculate these values separately? Wil a change in these values going to cause a drastic change in the result of the case?

Also, I'm trying to run the tutorial longer than 1 sec, now 3sec but OpenFOAM stops calculating after 2.79sec, finishing with an error: sigFpe and Foam::error:

rintStack(Foam::Ostream&). Changing the tolerances a little bit in the fvSolution-file resulted in a extension of the calculation to 2.93sec. Any idea how to solve the case for 5sec without giving an error?

Greetings,

daveatstyacht · December 29, 2010, 16:34

Jonas,
Those with the exception of "values= 32", the values listed are intrinsic either to the turbulence model itself or to turbulence theory (kappa = 0.41). If you change these values you will likely get something unphysical. Also if you neglect to have those lines, OF will default to the default values for them (which off the top of my head those are the values). The "values= 32" refers to the value of omega based on your given flow condition and this is the only value you are likely to want to change if you are changing things like velocity, viscosity, etc. Hope that helps.

Dave

December 29, 2010, 08:33	k-omega in wingmotion tutorial	#1
jlinterm New Member Jonas Lintermans Join Date: Dec 2010 Posts: 1 Rep Power: 0	Dear CFD-community, I would like to understand the following piece of code in the wingMotion-tutorial with pimpleDyMFoam-solver. In the 0/omega-file it states: Code: wing { type omegaWallFunction; Cmu 0.09; kappa 0.41; E 9.8; beta1 0.075; value uniform 32; } How can I calculate these values separately? Wil a change in these values going to cause a drastic change in the result of the case? Also, I'm trying to run the tutorial longer than 1 sec, now 3sec but OpenFOAM stops calculating after 2.79sec, finishing with an error: sigFpe and Foam::error:rintStack(Foam::Ostream&). Changing the tolerances a little bit in the fvSolution-file resulted in a extension of the calculation to 2.93sec. Any idea how to solve the case for 5sec without giving an error? Greetings,

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December 29, 2010, 16:34		#2
daveatstyacht Senior Member Dave Join Date: Jul 2010 Posts: 100 Rep Power: 16	Jonas, Those with the exception of "values= 32", the values listed are intrinsic either to the turbulence model itself or to turbulence theory (kappa = 0.41). If you change these values you will likely get something unphysical. Also if you neglect to have those lines, OF will default to the default values for them (which off the top of my head those are the values). The "values= 32" refers to the value of omega based on your given flow condition and this is the only value you are likely to want to change if you are changing things like velocity, viscosity, etc. Hope that helps. Dave