[P4tr1ck_St4r]

I am new in OpenFoam and I need to track a cloud of particles in a channel with periodic boundary conditions. I have two main problems:

1. The cyclic boundary condition looks not working for particles. They stick on the outlet boundary.

2. The particle's flow slowing down over time. I have read that this can be solved by adding fvOptions, but I don't know how to do that.

blockMeshDict

/*--------------------------------*- C++ -*----------------------------------*\
 | =========                 |                                                 |
| \\      /  F ield         | OpenFOAM: The Open Source CFD Toolbox           |
|  \\    /   O peration     | Version:  v2006                                 |
|   \\  /    A nd           | Website:  www.openfoam.com                      |
|    \\/     M anipulation  |                                                 |
\*---------------------------------------------------------------------------*/
FoamFile
{
    version     2.0;
    format      ascii;
    class       dictionary;
    object      blockMeshDict;
}
// * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * //

scale   1;  

vertices
(
    (0 0 0)
    (10 0 0)
    (10 1 0)
    (0 1 0)
    (0 0 2)
    (10 0 2)
    (10 1 2)
    (0 1 2)
);

blocks
(
    hex (0 1 2 3 4 5 6 7) (90 50 1) simpleGrading (1 1 1)
);

edges
(
);

boundary
(
    inlet
    {   
        type cyclic;
        neighbourPatch outlet;
        transform translational;
        separationVector (10 0 0);    
        faces
        (
            (4 7 3 0)
        );
     }   


    outlet
    {
        type cyclic;
        neighbourPatch inlet;
        transform translational;
        separationVector (-10 0 0);
        faces
        (
            (5 1 2 6)
        );
    }

    top
    {
        type wall;
        faces
        (
            (7 6 2 3)
        );
    }

    bottom
    {
        type wall;
        faces
        (
            (0 1 5 4)
        );
    }

    walls
    {
        type wall;
        faces
        (
            (4 5 6 7)
            (0 3 2 1)
        );
    }
);

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

kinematicCloudProperties

  /*--------------------------------*- C++ -*----------------------------------*\
| =========                 |                                                 |
| \\      /  F ield         | OpenFOAM: The Open Source CFD Toolbox           |
|  \\    /   O peration     | Version:  v2006                                 |
|   \\  /    A nd           | Website:  www.openfoam.com                      |
|    \\/     M anipulation  |                                                 |
\*---------------------------------------------------------------------------*/
FoamFile
{
    version     2.0;
    format      ascii;
    class       dictionary;
    location    "constant";
    object      kinematicCloudProperties;
}
// * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * //

solution
{
    active          true;
    coupled         true;
    transient       yes;
    cellValueSourceCorrection off;

    interpolationSchemes
    {
        rho.air         cell;
        U.air           cellPoint;
        mu.air          cell;
    }

    integrationSchemes
    {
        U               Euler;
    }

    sourceTerms
    {
        schemes
        {
            U semiImplicit 1;
        }
    }
}

constantProperties
{
    parcelTypeId 1;

    rhoMin          2;
    minParcelMass   1.04e-6;

    rho0            2;
    youngsModulus   1e8;
    poissonsRatio   0.35;

    constantVolume  true;

    alphaMax        0.99;
}

subModels
{
    particleForces
    {
        ErgunWenYuDrag
        {
            alphac alpha.air;
        }
        gravity;
    }

    injectionModels
    {
        model1
        {
            type            manualInjection;
            massTotal       0;
            parcelBasisType fixed;
            nParticle       1;
            SOI             0;
            positionsFile   "kinematicCloudPositions";
            U0              (0.5 0 0);
            sizeDistribution
            {
                type        fixedValue;
                fixedValueDistribution
                {
                    value   0.01;
                }
            }
        }
    }

    dispersionModel none;

    patchInteractionModel standardWallInteraction;

    StandardWallInteractionCoeffs
    {
        type rebound;
        e    0.97;
        mu   0.09;
    }

    heatTransferModel none;

    surfaceFilmModel none;

    collisionModel pairCollision;

    pairCollisionCoeffs
    {
        maxInteractionDistance  0.0025;

        writeReferredParticleCloud no;

        pairModel pairSpringSliderDashpot;

        pairSpringSliderDashpotCoeffs
        {
            useEquivalentSize   no;
            alpha               0.02;
            b                   1.5;
            mu                  0.10;
            cohesionEnergyDensity 0;
            collisionResolutionSteps 12;
        };

        wallModel wallSpringSliderDashpot;

        wallSpringSliderDashpotCoeffs
        {
            useEquivalentSize no;
            collisionResolutionSteps 12;
            youngsModulus   1e8;
            poissonsRatio   0.23;
            alpha           0.01;
            b               1.5;
            mu              0.09;
            cohesionEnergyDensity 0;
        };

        U     U.air;
    }

    stochasticCollisionModel none;

    radiation off;
}


cloudFunctions
{}


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

0/U.air

/*--------------------------------*- C++ -*----------------------------------*\
| =========                 |                                                 |
| \\      /  F ield         | OpenFOAM: The Open Source CFD Toolbox           |
|  \\    /   O peration     | Version:  v2006                                 |
|   \\  /    A nd           | Website:  www.openfoam.com                      |
|    \\/     M anipulation  |                                                 |
\*---------------------------------------------------------------------------*/
FoamFile
{
    version     2.0;
    format      binary;
    class       volVectorField;
    location    "0";
    object      U.air;
}
// * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * //

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

internalField   uniform (1 0 0);

boundaryField
{
    walls
    {
        type            noSlip;
    }

    top
    {
        type         noSlip;
    }

    bottom
    {
        type        noSlip;
    }

    outlet
    {
        type            cyclic;
    }

    inlet
    {
        type            cyclic;
    }
}


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

0/p

/*--------------------------------*- C++ -*----------------------------------*\
| =========                 |                                                 |
| \\      /  F ield         | OpenFOAM: The Open Source CFD Toolbox           |
|  \\    /   O peration     | Version:  v2006                                 |
|   \\  /    A nd           | Website:  www.openfoam.com                      |
|    \\/     M anipulation  |                                                 |
\*---------------------------------------------------------------------------*/
FoamFile
{
    version     2.0;
    format      ascii;
    class       volScalarField;
    object      p;
}
// * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * //

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

internalField   uniform 0;

boundaryField
{
    walls
    {
        type            fixedFluxPressure;
        phi             phi.air;
        value           $internalField;
    }

    inlet
    {   
        type            cyclic;
    }   

    outlet
    {   
        type            cyclic;
    }

    top
    {   
        type            fixedFluxPressure;
        phi             phi.air;
        value           $internalField;
    }

    bottom
    {   
        type            fixedFluxPressure;
        phi             phi.air;
        value           $internalField;
    }
}

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

Hope that helps!

[oswald]

1) One guess: I don't know what happens because you specified both, a patchInteractionModel and a collisionModel? Maybe you should switch one of them off.



2) As you have no boundary condition that keeps pressure/velocity constant at some patch, the coupling of the parcels with the flow's momentum in combination with their energy loss due to collisions should slowly decelerate the flow. You can try turning off "coupled" in kinematicCloudProperties and see if there is a change.