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sixDoFRigidBodyMotion with AMI in rotating system

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Old   September 24, 2017, 08:30
Default sixDoFRigidBodyMotion with AMI in rotating system
  #1
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Dae-young(Dan)
Join Date: Jan 2017
Location: South Korea
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Dear foamers,

I am trying to simulate a flow over a cylinder which is rotating with z-axis.

In this case, I set up the dynamicMeshDict and blockMesh as following.

dynamicMeshDict file is
Code:
/*--------------------------------*- C++ -*----------------------------------*\
| =========                 |                                                 |
| \\      /  F ield         | OpenFOAM: The Open Source CFD Toolbox           |
|  \\    /   O peration     | Version:  2.3.1                                 |
|   \\  /    A nd           | Web:      www.OpenFOAM.org                      |
|    \\/     M anipulation  |                                                 |
\*---------------------------------------------------------------------------*/
FoamFile
{
    version     2.0;
    format      ascii;
    class       dictionary;
    location    "constant";
    object      dynamicMeshDict;
}
// * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * //

dynamicFvMesh   dynamicMotionSolverFvMesh;

motionSolverLibs ( 
            "libfvMotionSolvers.so" 
            "libsixDoFRigidBodyMotion.so"
         );

//solver displacementLaplacian;
solver            sixDoFRigidBodyMotion;

/*
displacementLaplacianCoeffs
{

diffusivity uniform (cylinder);

}

*/


sixDoFRigidBodyMotionCoeffs
{
        patches         (cylinder);
        innerDistance   1;
        outerDistance   4;

        centreOfMass    (0 0 0);
    momentOfInertia    (0.3333 0.3333 0.3333);
    mass            2;
    orientation
    (
      1 0 0
      0 1 0
      0 0 1
      );
    
    veloicity    (0 0 0);
    acceleration    (0 0 0);
    angularMomentum    (0 0 0);
    torque        (0 0 0);
    gravity        (0 0 0);
    rho             rhoInf;
    rhoInf          1;
    report        on;

    solver
    {
        type CrankNicolson;
    }

    constraints
    {
        
     yLine
     {
       sixDoFRigidBodyMotionConstraint point;
       centreOfRotation    (0 0 0);
    //   direction        (0 0 1);
     }
     
       angular
         {
           sixDoFRigidBodyMotionConstraint axis;
           axis                 (0 0 1);
           //centreOfRotation   (0 0 0);
           //direction          (0 1 0);
         }
         
         
    }

    restraints
    {
      /*
     S1
     {
       sixDoFRigidBodyMotionRestraint linearSpring;
          anchor        (0 0 0);
          refAttachmentPt    (0 0 0);
          stiffness        35.0919;
          damping        0;
          restLength    0;
                 
     }
    */ 
     S3
     {
      sixDoFRigidBodyMotionRestraint sphericalAngularDamper;
          coeff 0;
     }
    }
}






/*

solver            sixDoFRigidBodyMotion;

sixDoFRigidBodyMotionCoeffs
{
    patches         (wing);
    innerDistance   0.3;
    outerDistance   1;

    mass            22.9;
    centreOfMass    (0.4974612746 -0.01671895744 0.125);
    momentOfInertia (1.958864357 3.920839234 2.057121362);
    orientation
    (
        0.9953705935 0.09611129781 0
        -0.09611129781 0.9953705935 0
        0 0 1
    );
    angularMomentum (0 0 -2);
    g               (0 -9.81 0);
    rho             rhoInf;
    rhoInf          1;
    report          on;

    solver
    {
        type symplectic;
    }

    constraints
    {
        yLine
        {
            sixDoFRigidBodyMotionConstraint line;
            centreOfRotation    (0.25 0.007 0.125);
            direction           (0 1 0);
        }

        zAxis
        {
            sixDoFRigidBodyMotionConstraint axis;
            axis                (0 0 1);
        }
    }

    restraints
    {
        verticalSpring
        {
            sixDoFRigidBodyMotionRestraint linearSpring;

            anchor          (0.25 0.007 0.125);
            refAttachmentPt (0.25 0.007 0.125);
            stiffness       4000;
            damping         2;
            restLength      0;
        }

        axialSpring
        {
            sixDoFRigidBodyMotionRestraint linearAxialAngularSpring;

            axis            (0 0 1);
            stiffness       700;
            damping         0.5;
            referenceOrientation $orientation;
        }
    }
}



*/
/*
sixDoFRigidBodyMotionCoeffs
{

centreOfMass    (0 0 0);
momentOfInertia    (0.2917 0.2917 0.25);
    mass         2;

patches    (cylinder);
innerDistance    0;
outerDistance    4;
    orientation
    (
      1 0 0
      0 1 0
      0 0 1
      );
    
    veloicity    (0 0 0);
    acceleration    (0 0 0);
    angularMomentum    (0 0 0);
    torque        (0 0 0);
    gravity        (0 0 0);
    rhoName        rhoInf;
    rhoInf        1;
    report        on;
diffusivity inverseDistance (cylinder);

}
*/
// ************************************************************************* //
and this is a boundary file

Code:
/*--------------------------------*- C++ -*----------------------------------*\
| =========                 |                                                 |
| \\      /  F ield         | OpenFOAM: The Open Source CFD Toolbox           |
|  \\    /   O peration     | Version:  4.1                                   |
|   \\  /    A nd           | Web:      www.OpenFOAM.org                      |
|    \\/     M anipulation  |                                                 |
\*---------------------------------------------------------------------------*/
FoamFile
{
    version     2.0;
    format      ascii;
    class       polyBoundaryMesh;
    location    "constant/polyMesh";
    object      boundary;
}
// * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * //

11
(
    outlet
    {
        type            patch;
        nFaces          240;
        startFace       210120;
    }
    sym1
    {
        type            patch;
        nFaces          360;
        startFace       210360;
    }
    sym2
    {
        type            patch;
        nFaces          360;
        startFace       210720;
    }
    inlet
    {
        type            patch;
        nFaces          240;
        startFace       211080;
    }
    cylinder
    {
        type            wall;
        inGroups        1(wall);
        nFaces          320;
        startFace       211320;
    }
    back
    {
        type            empty;
        inGroups        1(empty);
        nFaces          80000;
        startFace       211640;
    }
    back-calulated
    {
        type            empty;
        inGroups        1(empty);
        nFaces          25600;
        startFace       291640;
    }
    front
    {
        type            empty;
        inGroups        1(empty);
        nFaces          80000;
        startFace       317240;
    }
    front-calculated
    {
        type            empty;
        inGroups        1(empty);
        nFaces          25600;
        startFace       397240;
    }
    AMI_master
    {
        type            cyclicAMI;
        inGroups        1(cyclicAMI);
        nFaces          320;
        startFace       422840;
        matchTolerance  0.0001;
        transform       noOrdering;
        neighbourPatch  AMI_slave;
    }
    AMI_slave
    {
        type            cyclicAMI;
        inGroups        1(cyclicAMI);
        nFaces          320;
        startFace       423160;
        matchTolerance  0.0001;
        transform       noOrdering;
        neighbourPatch  AMI_master;
    }
)

// ************************************************************************* //
The body is rotated by a force induced by vortex sheds.

and I know I can rotate the mesh by applying omega in dynamicMesh, but in my case, I cannot use omega and it is calculated by the moment of inertia.

In this case, the mesh around body is morphed badly. As attached

I want to change it to rotate as a rigid body motion.

any suggestion for this problem I would be happy.

Thank you in advance.
Attached Images
File Type: jpg Morphed_mesh.jpg (189.3 KB, 116 views)
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Old   March 13, 2018, 16:20
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  #2
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David Balam
Join Date: Sep 2016
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Maybe the wingMotion Tutorial can help you
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