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InterDyMFoam unstable. InterFoam fine.

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Old   October 5, 2014, 11:29
Default InterDyMFoam unstable. InterFoam fine.
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Hi all,

I was hoping for some pointers. I have a case where I am trying to do some resistance predictions of a ship hull. The case runs fine using interFoam and seems to produce reasonable results.

If i try and run the same case with interDyMFoam the solution very quickly blows up, with the pressure forces becoming massive and the time step reducing so far as to cause a floating point exception.

I have also tried achieving a steady state with interFoam before continuing the run with interDyMFoam, with the same results.

My dynamicMeshDict is below, please let me know if there are any other outputs that would be useful:

Code:
DynamicFvMesh       dynamicMotionSolverFvMesh;

motionSolverLibs    ("libsixDoFRigidBodyMotion.so");

motionSolverLibs    ("libsixDoFRigidBodyMotion.so");

solver              sixDoFRigidBodyMotion;

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

    centreOfMass    (3.97 0 0.65);
    mass            10900;
    momentOfInertia (40 921 921);
    rhoInf          1;
    report          on;
    accelerationRelaxation 0.9;
    value           uniform (0 0 0);
value           uniform (0 0 0);

    constraints
    {
        zAxis
        {
            sixDoFRigidBodyMotionConstraint line;
            direction     (0 0 1);
        }
        yPlane
        {
            sixDoFRigidBodyMotionConstraint axis;
            axis          (0 1 0);
        }
    }

    restraints
    {
        translationDamper
  {
        translationDamper
        {
            sixDoFRigidBodyMotionRestraint linearDamper;
            coeff         8596;
        }
        rotationDamper
        {
            sixDoFRigidBodyMotionRestraint sphericalAngularDamper;
            coeff         11586;
        }
    }
}

Last edited by Denao; October 5, 2014 at 11:31. Reason: Further detail
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