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IDProjectCategoryView StatusDate SubmittedLast Update
0004177OpenFOAMBugpublic2024-11-13 08:522024-11-13 09:41
Reporterbonnymei Assigned Tohenry  
PrioritynormalSeverityminorReproducibilityhave not tried
Status closedResolutionno change required 
Product Versiondev 
Summary0004177: Inconsistent forces results between static mesh and rigidBodyMotion with ramp of 0
DescriptionI tested DTCHullMoving case with different setup and found some issues.

1. I ran the case with type none instead of motion Solver in dynamicMeshDict in order to do the calculation with fixed hull.
2. I ran the case with type motionSolver as is in tutorial case of DTCHullMoving and added ramp 0; in order not to move the hull such that it could be considered as fixed hull during the calculation.

in both the cases, PIMPLE setup in fvSolution is as follows:

PIMPLE
{
    momentumPredictor no;

    nOuterCorrectors 3;
    nCorrectors 1;
    nNonOrthogonalCorrectors 0;

    correctPhi yes;
    moveMeshOuterCorrectors no;
    transportCorrectionFinal no;
}

And then, the forces results were different
for case1, first 5th time step results reads

forces rigidBodyForces write:
    sum of forces:
        pressure : (-681.342 1920.48 3278.92)
        viscous : (-3.02022 0.0215809 0.0283866)
        porous : (0 0 0)
    sum of moments:
        pressure : (-787.341 -16955.4 11713.8)
        viscous : (-0.004812 -0.284848 -0.885415)
        porous : (0 0 0)

for case 2, first 5th time step results reads

forces rigidBodyForces write:
    sum of forces:
        pressure : (-205.606 2094.37 3981.09)
        viscous : (-3.0219 0.0243522 0.0324346)
        porous : (0 0 0)
    sum of moments:
        pressure : (-939.655 -13706.5 8323.41)
        viscous : (-0.00563766 -0.32313 -0.90175)
        porous : (0 0 0)

I doubted the corretPhi option but that option did not changed the result.

I think case1 and case2 show identical results technically but it doesn't.

dynamicMeshDict and fvSolution for the test are attached.
TagsNo tags attached.

Activities

bonnymei

2024-11-13 08:52

reporter  

dynamicMeshDict (1,907 bytes)    
/*--------------------------------*- C++ -*----------------------------------*\
  =========                 |
  \\      /  F ield         | OpenFOAM: The Open Source CFD Toolbox
   \\    /   O peration     | Website:  https://openfoam.org
    \\  /    A nd           | Version:  dev
     \\/     M anipulation  |
\*---------------------------------------------------------------------------*/
FoamFile
{
    format      ascii;
    class       dictionary;
    object      dynamicMeshDict;
}
// * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * //

mover
{
    type            motionSolver;

    libs            ("librigidBodyMeshMotion.so");

    motionSolver    rigidBodyMotion;

    report          on;

    solver
    {
        type Newmark;
    }

    //ramp  0;

    accelerationRelaxation 0.4;

    bodies
    {
        hull
        {
            type            rigidBody;
            parent          root;

            centreOfMass    (0 0 0);
            mass            412.73;
            inertia         (40 0 0 921 0 921);
            transform       (1 0 0 0 1 0 0 0 1) (2.929541 0 0.2);

            joint
            {
                type    composite;
                joints
                (
                    {
                        type Pz;
                    }
                    {
                        type Ry;
                    }
                );
            }

            patches         (hull);
            innerDistance   0.3;
            outerDistance   1;
        }
    }

    restraints
    {
        translationDamper
        {
            type linearDamper;
            body hull;
            coeff 8596;
        }

        rotationDamper
        {
            type sphericalAngularDamper;
            body hull;
            coeff 11586;
        }
    }
}


// ************************************************************************* //
dynamicMeshDict (1,907 bytes)   
fvSolution (1,921 bytes)    
/*--------------------------------*- C++ -*----------------------------------*\
  =========                 |
  \\      /  F ield         | OpenFOAM: The Open Source CFD Toolbox
   \\    /   O peration     | Website:  https://openfoam.org
    \\  /    A nd           | Version:  dev
     \\/     M anipulation  |
\*---------------------------------------------------------------------------*/
FoamFile
{
    format      ascii;
    class       dictionary;
    location    "system";
    object      fvSolution;
}
// * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * //

solvers
{
    "alpha.water.*"
    {
        nAlphaCorr      3;
        nAlphaSubCycles 1;

        MULESCorr       yes;
        nLimiterIter    15;
        alphaApplyPrevCorr  yes;

        solver          smoothSolver;
        smoother        symGaussSeidel;
        tolerance       1e-10;
        relTol          0;
        minIter         1;
    }

    "pcorr.*"
    {
        solver          GAMG;
        smoother        DIC;

        tolerance       1e-3;
        relTol          0;
    };

    p_rgh
    {
        solver          GAMG;
        smoother        DIC;

        tolerance       5e-8;
        relTol          0;
    };

    p_rghFinal
    {
        $p_rgh;
        relTol          0;
    }

    "(U|k|omega).*"
    {
        solver          smoothSolver;
        smoother        symGaussSeidel;

        nSweeps         1;
        tolerance       1e-7;
        relTol          0;
        minIter         1;
    };
}

PIMPLE
{
    momentumPredictor no;

    nOuterCorrectors 3;
    nCorrectors      1;
    nNonOrthogonalCorrectors 0;

    correctPhi      yes;
    moveMeshOuterCorrectors no; //yes;
    transportCorrectionFinal no; //yes;
}

relaxationFactors
{
    equations
    {
        ".*" 1;
    }
}

cache
{
    grad(U);
}


// ************************************************************************* //
fvSolution (1,921 bytes)   

henry

2024-11-13 09:41

manager   ~0013461

User support request, pending funding.

Issue History

Date Modified Username Field Change
2024-11-13 08:52 bonnymei New Issue
2024-11-13 08:52 bonnymei File Added: dynamicMeshDict
2024-11-13 08:52 bonnymei File Added: fvSolution
2024-11-13 09:41 henry Assigned To => henry
2024-11-13 09:41 henry Status new => closed
2024-11-13 09:41 henry Resolution open => no change required
2024-11-13 09:41 henry Note Added: 0013461