[chaz]

Hello,
I'm using openfoam 4.0, pimpleDyMFoam with rigid body motion.

I am attempting to simulate a solid disk in a fluid that changes angle on the x or y axis in response to an externally applied torque. I am not talking about the disk spinning, but am referring to the angle changing, as if it is a solar collector following the sun, for example. The disk's angle changes about its center, which is also the center of the computational domain, (0,0,0). The surrounding fluid is a contained volume, without inlets or outlets. From the tutorials and forum discussions, it is not clear that one can simulate motion of a rigid body caused by an external torque or force, whose motion is impeded by the presence of the fluid. Image attached.

I am basing my model on several tutorials, particularly /incompressible/pimpleDyMFoam/propeller/

Is it possible to model the response of a rigid body in a fluid in response to an applied external torque?

The center of the object is pined in space, and should allow the object to rotate. I'm attempting to apply torque using the sixDoFRigidBodyMotionCoeffs torque value. There is no motion in my model. If I remove the pin, I can see the object begin to fall due to gravity, however. dynamicMeshDict:

/*--------------------------------*- 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       dictionary;
    object      dynamicMeshDict;
}
// * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * //

dynamicFvMesh      dynamicMotionSolverFvMesh;

motionSolverLibs ("libsixDoFRigidBodyMotion.so");

solver            sixDoFRigidBodyMotion;

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

    mass            .001;
    centreOfMass    (0 0 0);
    momentOfInertia (.1 .1 .1);
    torque          (1000 1000 0);
    /*orientation
    (
        0.9953705935 0.09611129781 0
        -0.09611129781 0.9953705935 0
        0 0 1
    );*/
    angularMomentum (0 0 0);
    g               (0 0 -9.81);
    rho             rhoInf;
    rhoInf          1;
    report          on;

    solver
    {
        type symplectic;
    }


    constraints
    {
        point
        {
            sixDoFRigidBodyMotionConstraint point;
            centreOfRotation    (0 0 0);
        }


    }

}


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

By reducing the mass, increasing the torque, etc, I still do not see motion. How does one apply an external torque to a rigid body, to see the resulting fluid and body motion?

There are a few forum discussions that are related to this, such as one linking to: https://www.youtube.com/watch?v=wjr7NUe5hfg

The video seems to indicate that open foam can report the force or torque from the simulation, but force or torque can not be used as inputs to a simulation. The user takes torques from foam, calculates a new angle, then inputs an angular change of the wind turbine back into foam for the next step of the simulation. Any help would be appreciated!