[rdbisme]

Hello,

it's been a while I've been struggling with this without understanding why I'm getting this behaviour.

I'm trying to simulate a two-phase flow with solid particles inside a liquid carrier and, even if the velocity profiles for both phases are developed, no pressure drop is achieved in the pipe.

constant/polyMesh/boundary

/*--------------------------------*- C++ -*----------------------------------*\
| =========                 |                                                 |
| \\      /  F ield         | OpenFOAM: The Open Source CFD Toolbox           |
|  \\    /   O peration     | Version:  3.0.1                                 |
|   \\  /    A nd           | Web:      www.OpenFOAM.org                      |
|    \\/     M anipulation  |                                                 |
\*---------------------------------------------------------------------------*/
FoamFile
{
    version     2.0;
    format      ascii;
    class       polyBoundaryMesh;
    location    "constant/polyMesh";
    object      boundary;
}
// * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * //

3
(
    outlet
    {
        type            cyclic;
        inGroups        1(cyclic);
        nFaces          4500;
        startFace       667500;
        matchTolerance  0.0001;
        transform       unknown;
        neighbourPatch  inlet;
    }
    inlet
    {
        type            cyclic;
        inGroups        1(cyclic);
        nFaces          4500;
        startFace       672000;
        matchTolerance  0.0001;
        transform       unknown;
        neighbourPatch  outlet;
    }
    walls
    {
        type            wall;
        inGroups        1(wall);
        nFaces          6000;
        startFace       676500;
    }
)

// ************************************************************************* //

constant/fvOptions

/*--------------------------------*- C++ -*----------------------------------*\
| =========                 |                                                 |
| \\      /  F ield         | OpenFOAM: The Open Source CFD Toolbox           |
|  \\    /   O peration     | Version:  3.0.1                                 |
|   \\  /    A nd           | Web:      www.OpenFOAM.org                      |
|    \\/     M anipulation  |                                                 |
\*---------------------------------------------------------------------------*/
FoamFile
{
    version     2.0;
    format      ascii;
    class       dictionary;
    location    "constant";
    object      fvOptions;
}
// * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * //

momentumSource
{
    type            meanVelocityForce;
    active          yes;

    meanVelocityForceCoeffs
    {
        selectionMode   all;

        fieldNames      (U.SLN2);
        Ubar            (0 1.3 0);
    }
}

momentumSource1
{
    type            meanVelocityForce;
    active          yes;

    meanVelocityForceCoeffs
    {
        selectionMode   all;

        fieldNames      (U.LN2);
        Ubar            (0 1.3 0);
    }
}




// ************************************************************************* //

constant/phaseProperties

/*--------------------------------*- C++ -*----------------------------------*\
| =========                 |                                                 |
| \\      /  F ield         | OpenFOAM: The Open Source CFD Toolbox           |
|  \\    /   O peration     | Version:  3.0.0                                 |
|   \\  /    A nd           | Web:      www.OpenFOAM.org                      |
|    \\/     M anipulation  |                                                 |
\*---------------------------------------------------------------------------*/
FoamFile
{
    version     2.0;
    format      ascii;
    class       dictionary;
    location    "constant";
    object      phaseProperties;
}
// * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * //

phases (SLN2 LN2);

SLN2
{
    diameterModel   constant;
    constantCoeffs
    {
    d        1.3e-3;
    }
   residualAlpha    1e-6;
}

LN2
{
    diameterModel   constant;
    constantCoeffs
    {
        d               1;
    }
  
   residualAlpha    1e-6;
}

blending
{
    default
    {
        type            none;
    continuousPhase    LN2;

    }
}

sigma
(
    (SLN2 and LN2)     0
);

aspectRatio
(

);

drag
(
    (SLN2 in LN2)
    {
        type            SchillerNaumann;
        residualAlpha   1e-6;
        residualRe      1e-3;
        swarmCorrection
        {
            type        none;
        }
    }

    (LN2 in SLN2)
    {
        type            SchillerNaumann;
        residualAlpha   1e-6;
        residualRe      1e-3;
        swarmCorrection
        {
            type        none;
        }
    }


);

virtualMass
(
    (SLN2 in SLN2)
    {
        type            constantCoefficient;
        Cvm             0.5;
    }

    (LN2 in SLN2)
    {
        type            constantCoefficient;
        Cvm             0.5;
    }
);

heatTransfer
(
    (SLN2 in LN2)
    {
        type            RanzMarshall;
        residualAlpha   1e-4;
    }

    (LN2 in SLN2)
    {
        type            RanzMarshall;
        residualAlpha   1e-4;
    }
);

lift
(
);

wallLubrication
(
);

turbulentDispersion
(
);

// Minimum allowable pressure
pMin            10000;


// ************************************************************************* //

termophysicalProperties.LN2

/*--------------------------------*- C++ -*----------------------------------*\
| =========                 |                                                 |
| \\      /  F ield         | OpenFOAM: The Open Source CFD Toolbox           |
|  \\    /   O peration     | Version:  3.0.1                                 |
|   \\  /    A nd           | Web:      www.OpenFOAM.org                      |
|    \\/     M anipulation  |                                                 |
\*---------------------------------------------------------------------------*/
FoamFile
{
    version     2.0;
    format      ascii;
    class       dictionary;
    location    "constant";
    object      thermophysicalProperties.LN2;
}
// * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * //

thermoType
{
    type            heRhoThermo;
    mixture         pureMixture;
    transport       const;
    thermo          hConst;
    equationOfState perfectFluid;
    specie          specie;
    energy          sensibleInternalEnergy;
}

mixture
{
    specie
    {
        nMoles      1;
        molWeight   14;
    }
    equationOfState
    {
    R        3000;
    rho0        867.86;
    }
    thermodynamics
    {
        Cp          2000;
        Hf          25560;
    }
    transport
    {
        mu          294.92e-6;
        Pr          2.7975;
    }
}


// ************************************************************************* //

thermoPhysicalProperties.SLN2 (solid)

/*--------------------------------*- C++ -*----------------------------------*\
| =========                 |                                                 |
| \\      /  F ield         | OpenFOAM: The Open Source CFD Toolbox           |
|  \\    /   O peration     | Version:  3.0.1                                 |
|   \\  /    A nd           | Web:      www.OpenFOAM.org                      |
|    \\/     M anipulation  |                                                 |
\*---------------------------------------------------------------------------*/
FoamFile
{
    version     2.0;
    format      ascii;
    class       dictionary;
    location    "constant";
    object      thermophysicalProperties.SLN2;
}
// * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * //

thermoType
{
    type            heRhoThermo;
    mixture         pureMixture;
    transport       const;
    thermo          hConst;
    equationOfState rhoConst;
    specie          specie;
    energy          sensibleInternalEnergy;
}

mixture
{
    specie
    {
        nMoles      1;
        molWeight   14;
    }
    equationOfState
    {
    rho        1026.5;
    }
    thermodynamics
    {
        Cp          1660;
        Hf          25560;
    }
    transport
    {
        mu          294.92e-6;
        Pr          2.42;
    }
}


// ************************************************************************* //

0/alpha.SLN2

/*--------------------------------*- C++ -*----------------------------------*\
| =========                 |                                                 |
| \\      /  F ield         | OpenFOAM: The Open Source CFD Toolbox           |
|  \\    /   O peration     | Version:  3.0.1                                 |
|   \\  /    A nd           | Web:      www.OpenFOAM.org                      |
|    \\/     M anipulation  |                                                 |
\*---------------------------------------------------------------------------*/
FoamFile
{
    version     2.0;
    format      ascii;
    class       volScalarField;
    location    "0";
    object      alpha.SLN2;
}
// * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * //

dimensions      [0 0 0 0 0 0 0];

internalField   uniform 0.13;

boundaryField
{
    outlet
    {
        type            cyclic;
    }
    inlet
    {
        type            cyclic;
    }
    walls
    {
        type            zeroGradient;
    }
}


// ************************************************************************* //

Other settings summarized:

• k-epsilon just for the liquid phase
  • epsilonWallFunction on the wall
  • zeroGradient for k on the wall
• fixedFluxPressure on wall for p and p_rgh
• fixedValue: 0 for velocities on walls
• No energy equation (not solving it)

If any other details needed, ask! =)