[pruthvi1991]

Hello guys I need to simulate an airfoil undergoing pitch + plunge as is done in the paper kinsey and dumas.

The pitch and plunge equations are as follows.

H = h *sin(wt)
theta = theta*cos(wt)

I used the following dynamicMeshDict file.

dynamicFvMesh      dynamicMotionSolverFvMesh;

motionSolverLibs ("libsixDoFRigidBodyMotion.so");

solver            sixDoFRigidBodyMotion;

sixDoFRigidBodyMotionCoeffs
{
    patches         (wing);
    innerDistance   0.3;
    outerDistance   14;

    mass            10000;
    centreOfMass    (0.3 0  0.125);
    momentOfInertia (1.958864357 3.920839234 10000);
    orientation
    (
        1 0 0
        0 1 0
        0 0 1
    );
    angularMomentum (0 0 -1579.136704); //605.3357367);
    velocity	    (0 0 0); //0.1507964474 0);
    g               (0 0 0);
    rhoName         rhoInf;
    rhoInf          2.5;
    report          on;

    constraints
    {
        yLine
        {
            sixDoFRigidBodyMotionConstraint line;
            centreOfRotation    (0.3 0 0.125);
            direction           (0 1 0);
        }

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

    restraints
    {
        verticalSpring
        {
            sixDoFRigidBodyMotionRestraint linearSpring;

            anchor          (0.3 -1 0.125);
            refAttachmentPt (0.3 0  0.125);
            stiffness       227.3956854;
            damping         0;
            restLength      2;
        }

        axialSpring
        {
            sixDoFRigidBodyMotionRestraint linearAxialAngularSpring;

            axis            (0.3 0 1);
            stiffness       227.3956854;
            damping         0;
            referenceOrientation $orientation;
        }
    }
}

I find that the resulting motion is not repeated consistently. Click here to check the video and you can observe that the trailing edge doesn't reach the initial position and steadily moves farther away. Any suggestions on how to fix that?



Thanks,
Pruthvi.