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kOmegaSST Boundary Conditions for Supersonic Nozzle

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Old   September 17, 2018, 11:10
Default kOmegaSST Boundary Conditions for Supersonic Nozzle
  #1
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I've been working on modeling an axisymmetric supersonic nozzle by doing a 2D calculation in OpenFOAM. I believe there is something wrong with my turbulence (komegasst) conditions as my plots appear to be laminar.

I am modelling a Mach 2.5 C-D nozzle, pressure boundary conditions are 34.6 PSI at the inlet.

For k:
Code:
boundaryField
{
    right
    {
        type            wedge;
    }
    left
    {
        type            wedge;
    }
    nozzle
    {
        type            kqRWallFunction;
        value           uniform 1;
    }
    inlet
    {
        type            turbulentIntensityKineticEnergyInlet;
        intensity       0.05;
        value           uniform 1;
    }
    outlet
    {
        type            inletOutlet;
        inletValue      uniform 1;
        value           uniform 1;
    }
}
For omega:
Code:
{
    inlet
    {
        type            zeroGradient;
    }
    outlet
    {
        type            zeroGradient;
    }
    nozzle
    {
        type            omegaWallFunction;
        Cmu             0.09;
        kappa           0.41;
        E               9.8;
        value           uniform 2.6;
    }
    right
    {
        type            wedge;
    }
    left
    {
        type            wedge;
    }
}
For alphat:
Code:
{
    inlet
    {
        type            calculated;
        value           uniform 0.001;
    }
    outlet
    {
        type            calculated;
        value           uniform 0.001;
    }
    left
    {
        type            wedge;
    }
    right
    {
        type            wedge;
    }
    nozzle
    {
        type            compressible::alphatWallFunction;
        value           uniform 0.001;
    }
}
For nut:
Code:
{
    right
    {
        type            wedge;
    }
    left
    {
        type            wedge;
    }
    nozzle
    {
        type            nutkWallFunction;
        value           uniform 0;
    }
    inlet
    {
        type            calculated;
        value           uniform 0;
    }
    outlet
    {
        type            calculated;
        value           uniform 0;
    }
}
For epsilon:
Code:
{
    right
    {
        type            wedge;
    }
    left
    {
        type            wedge;
    }
    nozzle
    {
        type            epsilonWallFunction;
        value           uniform 200;
    }
    inlet
    {
        type            turbulentMixingLengthDissipationRateInlet;
        mixingLength    0.005;
        value           uniform 200;
    }
    outlet
    {
        type            inletOutlet;
        inletValue      uniform 200;
        value           uniform 200;
    }
}
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Old   September 17, 2018, 12:43
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Luis Eduardo
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Hi,

Could you share the file "turbulenceProperties"? Could you also share the results you got?

Best Regards,
Luis
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Old   September 17, 2018, 13:06
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I've zipped up all my case files and put them on Google Drive: LINK.

Here is a link to a plot of my velocity profile: LINK. The blue dotted line is the boundary layer found by experimental data. The orange dotted line is the boundary layer calculated from OpenFOAM. The velocity profile itself just doesn't look right...

Turbulence Properties:
Code:
simulationType  RAS;

RAS
{
    RASModel        kOmegaSST;

    turbulence      on;

    printCoeffs     on;
}
Thermophysical Properties:

Code:
thermoType
{
    type            hePsiThermo;
    mixture         pureMixture;
    transport       sutherland;
    thermo          hConst;
    equationOfState perfectGas;
    specie          specie;
    energy          sensibleInternalEnergy;
}

mixture
{
    specie
    {
        molWeight   28.9;
    }
    thermodynamics
    {
        Cp          1007;
        Hf          0;
    }
    transport
    {
        As          1.4792e-06;
        Ts          116;
    }
}
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