[jumpa72]

Hi, I'm running a simulation of a cross-flow turbine, with interDyMFoam.
I've modeled the rotor with the 6-dof rigid body motion. The simulation is running fine, but I've a problem.
The rotor is spinning aroung Z-axis.
Here is the dynamicMeshDict

sixDoFRigidBodyMotionCoeffs 
{ 
    patches         (pala); 
    innerDistance   1e5; // Extent of the solid-body motion region around body 
    outerDistance   1.1e5; // Extent of mesh-morphing region around body 

    centreOfMass    (0 0 0); 
    mass            2; 
    momentOfInertia (0.06 0.06 0.005); 
        orientation
        (
            1 0 0
            0 1 0
            0 0 1
        );
    velocity        (0 0 0);
    acceleration    (0 0 0);
    angularMomentum (0 0 0);

//    torque  (0 0 666)
    report          on; 
    accelerationRelaxation 0.3; 
    value           uniform (0 0 0); 

    constraints 
    { 
        zAxis 
        { 
            sixDoFRigidBodyMotionConstraint axis; 
            axis          (0 0 1); 
        }
    fixedPt
    {
        sixDoFRigidBodyMotionConstraint point;
         point    (0 0 0);
    }
         
    } 

    restraints
    {
        rotationDamper
        {
           sixDoFRigidBodyMotionRestraint sphericalAngularDamper;
           coeff         0.1;
        }
    }

}

If the torque parameter is commented, in the mesh.update phase of the solution I've reported the 6-dof parameter update, including the angular velocity:

Restraint rotationDamper:  moment (-0 -0 23.903004)
6-DoF rigid body motion
    Centre of rotation: (0 0 0)
    Centre of mass: (0 0 0)
    Orientation: (0.70693806 -0.70727546 0 0.70727546 0.70693806 0 0 0 1)
    Linear velocity: (0 0 0)
    Angular velocity: (0 0 -239.03019)
AMI: Creating addressing and weights between 4156 source faces and 1904 target faces
AMI: Patch source sum(weights) min/max/average = 0.91803358, 1.004191, 1.0000864
AMI: Patch target sum(weights) min/max/average = 0.80581278, 1.0025247, 0.99988022
Execution time for mesh.update() = 0.58 s
smoothSolver:  Solving for alpha.water, Initial residual = 0.00032745617, Final residual = 8.2593505e-10, No Iterations 3
Phase-1 volume fraction = 0.5470669  Min(alpha1) = 0  Max(alpha1) = 1.0104109
MULES: Correcting alpha.water
MULES: Correcting alpha.water
Phase-1 volume fraction = 0.54706693  Min(alpha1) = -0.0002051717  Max(alpha1) = 1.0104109
smoothSolver:  Solving for Ux, Initial residual = 0.00030591356, Final residual = 6.5264777e-07, No Iterations 2
smoothSolver:  Solving for Uy, Initial residual = 0.00011866999, Final residual = 2.7919284e-07, No Iterations 2
GAMG:  Solving for p_rgh, Initial residual = 0.00066497002, Final residual = 3.3393962e-05, No Iterations 2
time step continuity errors : sum local = 4.3662479e-08, global = -7.3058715e-10, cumulative = -0.00011849602
...

If the torque parameter is given, then I have no data of 6-dof parameter:

AMI: Creating addressing and weights between 4156 source faces and 1904 target faces
AMI: Patch source sum(weights) min/max/average = 0.65915578, 1.0035944, 0.99996507
AMI: Patch target sum(weights) min/max/average = 0.75657687, 1.0023823, 0.9998494
Execution time for mesh.update() = 0.57 s
smoothSolver:  Solving for alpha.water, Initial residual = 0.00034930917, Final residual = 1.1702469e-09, No Iterations 3
Phase-1 volume fraction = 0.54706979  Min(alpha1) = 0  Max(alpha1) = 1.0104363
MULES: Correcting alpha.water
MULES: Correcting alpha.water
...

My question is, is there a method to get the angular velocity of a 6-dof moving mesh?
tnx in advance
Gianpaolo

[tomf]

Hi Gianpaolo,

I am guessing that it is caused by this:

In your commented block there is no closing semicolon on your "torque line". Since you have commented this line there is no problem, however if you uncomment the line, the line is not closed, so OpenFOAM will not read the next line, which specifies that it must report (to the log).

Hope this helps,

Regards,
Tom

[jumpa72]

yes!
Thank you Tom, that's the problem!

Another question:
is there any detailed description of the six dof parameter?
I've found only the brief description in the .H file of six dof body motion...

tnx
Gianpaolo

[tomf]

Hi,

I do not think there is something like that available from OpenFOAM directly, maybe you can find something by googling it, if someone has started to analyse it and make it available. I also do not know that much more about the particular library, just spotted the error since I made it myself so many times (in other applications) as well.

Regards,
Tom

[vava10]

hey,

How is the restraints coefficients determined?

[Himanshu_Shrivastava]

Hello,
I am running simulation for kalpan turbine with 6DOF, but the angular velocity keep on increasing.
Does that happen with your simulation?

[@ss]

Hello,
I also want to know how the 6dof rigid body motion equation is written in openFoam directly