[tok3rat0r]

I'm currently running a simple model of a boat hull moving at constant velocity on an initially flat free surface with interDyMFoam.

This is my dynamicMeshDict for the sixDoFRigidBodyMotion solver:

dynamicFvMesh   dynamicMotionSolverFvMesh;

motionSolverLibs    ("libsixDoFRigidBodyMotion.so");

solver    sixDoFRigidBodyMotion;

sixDoFRigidBodyMotionCoeffs {
patches         (boat);
innerDistance   0.2;
outerDistance   1.2;

centreOfMass    (-3.2 0 0.7);
mass            11000;
momentOfInertia (4413 22295 20859);
rhoInf          1;
report          on;

//value uniform (0, 0, 0);

accelerationRelaxation 0.05;
accelerationDamping 0.9;

solver
{
    type Newmark;
}
}

Using this, the centre of mass and rotation are coincident as expected, and everything seems fine (I've no idea what the value uniform (0, 0, 0) field is for, and commenting it out doesn't seem to change anything). My question is, how do I translate this to a suitable dictionary for the 'new' solver rigidBodyMotion? My best guess (based on the DTCHull tutorial) is as follows, but I'm not sure about the centreOfMass and transform fields: does 'transform' affect both the centre of mass and the centre of rotation, moving the centre of mass from (0,0,0) to (-3.2,0,0.7) in this case, or does it only affect the centre of rotation (relevant to the inertia tensor)? I've also no idea what the joint structure is there for.

dynamicFvMesh   dynamicMotionSolverFvMesh;

motionSolverLibs   ("librigidBodyMeshMotion.so");

solver    rigidBodyMotion;

rigidBodyMotionCoeffs {
report          on;

solver
{
    type Newmark;
}

accelerationRelaxation 0.05;
accelerationDamping 0.9;

bodies
{
    boat
    {
        type            rigidBody;
        parent          root;

        centreOfMass    (0 0 0);
        mass            11000;
        inertia (4413 0 0 22295 0 20859);
        transform       (1 0 0 0 1 0 0 0 1) (-3.2 0 0.7);

        joint
        {
            type    composite;
            joints
            (
                {
                    type Pz;
                }
                {
                    type Ry;
                }
            );
        }

        patches         (boat);
        innerDistance   0.2;
        outerDistance   1.2;
    }
}
}

[VigneshSP]

i think thats a translational constraint in a combined form if u run the sixDoFRigidBodyMotion solver we have to specify the constraint under constraints funtion like highlighted below

motionSolverLibs    ("libsixDoFRigidBodyMotion.so");

dynamicFvMesh       dynamicOversetFvMesh;

dynamicOversetFvMeshCoeffs
{
}

solver          sixDoFRigidBodyMotion;

sixDoFRigidBodyMotionCoeffs
{

    patches         (floatingObject);
    innerDistance   100.0;
    outerDistance   101.0;

    centreOfMass    (0 0 0);

    // Cuboid dimensions
    

    // Density of the solid
    rhoSolid        780;

    // Cuboid mass
    mass            0.40872;

    // Cuboid moment of inertia about the centre of mass
    momentOfInertia (1.21327e-05 1.21327e-05 1.21327e-05);
    velocity (0 0 0);
    report          on;
    accelerationRelaxation 0.6;

    solver
    {
        type Newmark;
    }

    constraints
    {

        
        /*fixedPoint
        {
             sixDoFRigidBodyMotionConstraint point;
             centreOfRotation (0.5 0.45 0.1);
        }*/
        

        /*fixedLine
        {
            sixDoFRigidBodyMotionConstraint line;
            //centreOfRotation (0.5 0.45 0.1);
            direction (0 0 1);
        }*/

        
        /*fixedAxis
        {
            sixDoFRigidBodyMotionConstraint axis;
            axis (1 1 1);
        }*/
    /*arrestRotation
     {
           sixDoFRigidBodyMotionConstraint   orientation;
           
     }*/

        
    }
}

while running the above the output log generated

/*---------------------------------------------------------------------------*\
| =========                 |                                                 |
| \\      /  F ield         | OpenFOAM: The Open Source CFD Toolbox           |
|  \\    /   O peration     | Version:  v1806                                 |
|   \\  /    A nd           | Web:      www.OpenFOAM.com                      |
|    \\/     M anipulation  |                                                 |
\*---------------------------------------------------------------------------*/


// * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * //
Create time

Create mesh for time = 0

Selecting dynamicFvMesh dynamicOversetFvMesh
Selecting motion solver: sixDoFRigidBodyMotion
Selecting sixDoFSolver Newmark
Translational constraint tensor (1 0 0 0 1 0 0 0 1)
Rotational constraint tensor (1 0 0 0 1 0 0 0 1)

PIMPLE: no residual control data found. Calculations will employ 2 corrector loops

Reading field p_rgh

Reading field U

Reading/calculating face flux field phi

Creating cellMask field to block out hole cells