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Old   January 13, 2013, 07:34
Default k-epsilon and pisoFoam
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zaynah K.
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hi..
i have a case where i have sent a 2m/s velocity and observe the trail around a cube.
I have successfully done it in Fluent.

i had as boundary condition the inlet velocity, the outflow and the symmetry for my domain then the wall for the cube. i was in turbulent regime and using K-epsilon model with Simple algorithm.

Now i wish to apply it to Openfoam.
so i chose pisoFoam and Ras model

I have changed my U and P Boundary cond accordingly..
My problem is i do not know how to modify the K-epsilon and fv solution and fv scheme accordingly..

Any idea from the experienced user on how to modify the above mentioned specifications??



Regards
zaynah
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Old   January 13, 2013, 16:12
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As a starting point, have a look at one of the tutorial cases.

You should use wall functions for k (kqRWallFunction), epsilon (epsilonWallFunction) and nut (nutUWallFunction) at the walls.

At the inlet you can use the following two boundary conditions to estimate k and epsilon based on the turbulent intensity and the length scale:

turbulentMixingLengthDissipationRateInlet for epsilon

turbulentIntensityKineticEnergyInlet for k
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Old   January 13, 2013, 23:13
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zaynah K.
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hi thanks for your reply.
here is my modified files but i found this error..


Quote:
keyword s2 is undefined in dictionary "/home/zaynah/Desktop/cavity/0/epsilon::boundaryField"

file: /home/zaynah/Desktop/cavity/0/epsilon::boundaryField from line 26 to line 54.

From function dictionary::subDict(const word& keyword) const
in file db/dictionary/dictionary.C at line 461.

FOAM exiting
my epsilon file
Quote:
dimensions [0 2 -3 0 0 0 0];

internalField uniform 6.768e-6;

boundaryField
{
wall
{
type epsilonWallFunction;
value uniform 0;
}

p
{
type fixedValue;
value uniform 6.768e-6;

s1
{
type symmetryPlane;
value uniform 0;
}

s2
{
type symmetryPlane;
value uniform 0;
}

v
{
type fixedValue;
value uniform 6.768e-6;
}
frontAndBack
{
type empty;
}
}

Last edited by zaynah04; January 14, 2013 at 10:34.
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Old   January 17, 2013, 07:23
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Gregor Olenik
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Hi zaynah,you have a missing curly bracket at the defintion of p
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Old   January 20, 2013, 03:26
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zaynah K.
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hi Gregor..
in fact you are right and also i had done a mistake on the K file in Boundary condition..
it now work beautifully..
thanks
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