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-   -   Launder Shrma Low Reynolds turbulence model case setup (http://www.cfd-online.com/Forums/openfoam-pre-processing/122841-launder-shrma-low-reynolds-turbulence-model-case-setup.html)

sivakumar August 29, 2013 06:11

Launder Shrma Low Reynolds turbulence model case setup
 
Hi,
I am running a simulation with low Re turbulence model, I have checked the mesh, it is fine, there is no problem in it.

I came up with successful case setup for kOmegaSST. It is working fine, but the results are deviating.

So now I want to do the simulation with LaunderSharmaKE model, for that I am trying many different settings but none of them is working.

I know that we no need to give any wall function for lowRe model, so I have given fixedValues for that.

The BC's are as follows for SimpleFoam, Please have a look and help me.

0/k:

internalField uniform 0.39;

boundaryField
{
inlet
{
type fixedValue;
value uniform 0.39;
}

outlet
{
type zeroGradient;
}

top0 // wall
{
type fixedValue;
value uniform 1e-12;
}

0/epsilon:

inlet
{
type fixedValue;
value uniform 0.26295;
}

outlet
{
type zeroGradient;
}

top0 // wall
{
type fixedValue;
value uniform 1e-10;
}

0/nut:

internalField uniform 0;

boundaryField
{
inlet
{
type calculated;
value uniform 0;
}

outlet
{
type calculated;
value uniform 0;
}

top0 // wall
{
type nutLowReWallFunction;
value uniform 0;
}

0/p:

internalField uniform 0;

boundaryField
{
inlet
{
type zeroGradient;
}

outlet
{
type fixedValue;
value uniform 0;
}

top0 // wall
{
type zeroGradient;
}

0/U:

internalField uniform (0 0 0);

boundaryField
{
outlet
{
type zeroGradient;
}
inlet
{
type flowRateInletVelocity;
flowRate 2; // Volumetric/mass flow rate [m3/s or kg/s]
value uniform (0 0 0); // placeholder
}
top0 //wall
{
type fixedValue;
value uniform (0 0 0);
}

Thanks,
Sivakumar

sivakumar September 5, 2013 11:34

Hi there,
Still I am not winning, some one please help me.
I have done small change according to OpenFOAM training manual.

for Wall,

nut ----> fixedValue 0
k ------> fixedValue 0 (1e-12)
epsilon ->zeroGradient but I have given small fixedValue (1e-10)

k is always bounding for the above setting.
I dont understand what is the problem, please help me.


Thanks,
Sivakumar

JR22 September 5, 2013 13:18

I set up a case for buoyantBousinesqPimpleFoam and your turbulent model using HelyxOS. Setup a test case with a simple geometry and try using the BC's they setup. For me it worked at that time.

sivakumar September 14, 2013 08:20

Hi there,
I am happy to give you this information, the case setup for low Re model is successful. my problem was Y+ value, it was 1 or less, according the available information it is correct, but it is not at all working with Y+ of 1 or less. So I changed the Y+ value 3 -5, it is working fine. I hope I will get the good result.

Regarding the wall function,

low Re model wall function no need and
high Re model yes wall function need.

Low Re model:

turbulence model : LaunderSharmaKE

nut ----> fixedValue (0)
k -----> fixedValue (1e-12)
epsilon -----> fixedValue (1e-8) it can be zeroGradient as well
nuTilda -----> fixedValue (0)

for high Re model:

nut ----> nutkWallFunction value (0)
k -------> kqRWallFunction value uniform (*******)
epsilon ----> epsilonWallFunction value uniform (*******)
nuTilda -----> zeroGradient

I hope it will be useful.

Thanks,
Sivakumar


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