[PenPencil]

Hello all,


I am currently working on a 2D case where the cylinder translates as the effect of the flow around it (vortex-induced vibration) and it spins around its own axis at a constant angular speed. An illustration of the translating motion is like this: https://en.wikipedia.org/wiki/Vortex...V_cylindre.gif (this illustration does not include rotation of the cylinder).

I have been able to put the cylinder in translating motion, but I am confused as to how I can impart the angular velocity to it.



Please see below my dynamicMeshDict:

dynamicFvMesh    dynamicMotionSolverFvMesh;

motionSolverLibs (sixDoFRigidBodyMotion);

motionSolver     sixDoFRigidBodyMotion;

patches          (cylinder);
innerDistance    2.5;
outerDistance    8;

mass             2.5918139; 
centreOfMass     (0 0 0.5);
momentOfInertia  (0.378 0.378 0.324); 
g                (0 0 0); 
rho              rhoInf;
rhoInf           1;
report           on;
reportToFile     on;

solver
{
    type Newmark;
}

constraints 
{
    yLine
    {
        sixDoFRigidBodyMotionConstraint line;
        centreOfRotation    (0 0 0.5);
        direction           (0 1 0);
    }

    zAxis
    {
        sixDoFRigidBodyMotionConstraint orientation;
        axis                (0 0 0.5);
    }
}

restraints
{
    verticalSpring // modelling of the translation as mass-spring-damping system
    {
        sixDoFRigidBodyMotionRestraint linearSpring;

        anchor          (0 0 0.5);
        refAttachmentPt (0 0 0.5);
        stiffness       4.09246;
        damping         0.0026;
        restLength      0;
    }

}

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

My 0/U dict is like the following:

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

internalField   uniform (1 0 0);

boundaryField
{
    CYL
    {
        type            movingWallVelocity;
        value           uniform (0 0 0);
    }

    INLET
    {
        type            fixedValue;
        value           $internalField;
    }
    OUTLET
    {
        type            zeroGradient;
    }
    SIDES
    {
        type            symmetry;
    }
    FRONT
    {
        type            empty;
    }
    BACK
    {
        type            empty;
    }
}

There's a nice wiki page on this, but it seems to me that the rotation mentioned there is related to the rotation of the mesh. I do not believe this is necessary. I only want the mesh to deform according to the translation, whereas the rotation should not distort the mesh. As a matter of fact, for a non-translating cylinder I know I could use something like:

cyl
{

        type            rotatingWallVelocity;
        origin          ( -0.204735636 -0.49427555 0 );
        axis            ( 0 0 1 );
        omega           constant 26.3664;
}

But I do not know how to include this in the translating motion, i.e., either in the dynamicMeshDict or in the 0/U dictionary.

Could anyone help?

[PenPencil]

Dear Admin,


Could you please move this thread to the 'pre-processing' OpenFOAM forum, please?
I believe this topic would have been better positioned there. Sorry for the misplacement and thanks.