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Jet simulation using pimplefoam(LES)0OF2112

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Old   July 7, 2022, 01:29
Default Jet simulation using pimplefoam(LES)0OF2112
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Farzad Faraji
Join Date: Nov 2019
Posts: 205
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Hello all
I am using pimpleFoam(LES) to simulate water jet. My mesh is good and it can resolve the jet, but I need to add synthetic turbulence in to nozzle jet since it is to strong and coherent without entrance turbulence. I am using OF2112, U(especially turbulentDFSEMInlet)and P boundary conditions as I put in below.
With 10% turbulence intensity, my jet is still very coherent and does not dissipate as I attached the jet figure to this thread. what should I do? Are mt Turbulence Intensity parameter defined logically?
Nozzle diameter = 0.005 m
Nozzle velocity = 0.64 m/s

Boundary conditions for Nozzle_Outlet (turbulentDFSEMInlet);

Code:
 Nozzle_Outlet
    {
    type            turbulentDFSEMInlet;
    delta           0.005; // 1*0.005; //Characteristic length scale	

    
     R    uniform (0.004096 0.0 0.0 0.004096 0.0 0.004096);     // 10%*0.64==>0.064=======>0.064^2=0.004096
        
     U               uniform (0.0 0.64 0.0);
     value	      uniform (0.0 0.64 0.0);
        
     L               uniform 0.001;   // 0.2*0.005=0.001

     nCellPerEddy    2;
		
    }
Boundary conditions for Velocity;

Code:
/*--------------------------------*- C++ -*----------------------------------*\
  =========                 |
  \\      /  F ield         | OpenFOAM: The Open Source CFD Toolbox
   \\    /   O peration     | Website:  https://openfoam.org
    \\  /    A nd           | Version:  6
     \\/     M anipulation  |
\*---------------------------------------------------------------------------*/
FoamFile
{
    version     2.0;
    format      ascii;
    class       volVectorField;
    location    "0";
    object      U;
}
// * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * //

dimensions      [0 1 -1 0 0 0 0];

internalField   uniform (0 0 0);

boundaryField
{
    TopWall
    {
        type            inletOutlet;
        inletValue      uniform (0 0 0);
        value           uniform (0 0 0);
    }
    fixedWalls
    {
        type            fixedValue;
        value           uniform (0 0 0);
    }
    Nozzle_solidBodys
    {
        type            fixedValue;
        value           uniform (0 0 0);
    }
    Nozzle_Outlet
    {
    type            turbulentDFSEMInlet;
    delta           0.005; // 1*0.005; //Characteristic length scale	

    
     R               uniform (0.004096 0.0 0.0 0.004096 0.0 0.004096);     // 10%*0.64==>0.064=======>0.064^2=0.004096
        
     U               uniform (0.0 0.64 0.0);
     value	      uniform (0.0 0.64 0.0);
        
     L               uniform 0.001;   // 0.2*0.005=0.001

     nCellPerEddy    2;
		
    }
}


// ************************************************************************* //
And for pressure, we have below boundary condition;
Code:
/*--------------------------------*- C++ -*----------------------------------*\
  =========                 |
  \\      /  F ield         | OpenFOAM: The Open Source CFD Toolbox
   \\    /   O peration     | Website:  https://openfoam.org
    \\  /    A nd           | Version:  6
     \\/     M anipulation  |
\*---------------------------------------------------------------------------*/
FoamFile
{
    version     2.0;
    format      ascii;
    class       volScalarField;
    location    "0";
    object      p;
}
// * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * //

dimensions      [0 2 -2 0 0 0 0];

internalField   uniform 0;

boundaryField
{
    TopWall
    {
        type            fixedMean;
        meanValue       constant 0;
        value           uniform 0;
    }
    fixedWalls
    {
        type            fixedFluxPressure;
        gradient        uniform 0;
        value           uniform 0;
    }
    Nozzle_solidBodys
    {
        type            fixedFluxPressure;
        gradient        uniform 0;
        value           uniform 0;
    }
    Nozzle_Outlet
    {
        type            zeroGradient;
    }
}


// ************************************************************************* //
Thanks,
Farzad
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