softWall.C

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    Copyright (C) 2022 OpenCFD Ltd.
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License
    This file is part of OpenFOAM.

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#include "softWall.H"
#include "addToRunTimeSelectionTable.H"
#include "sixDoFRigidBodyMotion.H"

// * * * * * * * * * * * * * * Static Data Members * * * * * * * * * * * * * //

namespace Foam
{
namespace sixDoFRigidBodyMotionRestraints
{
    defineTypeNameAndDebug(softWall, 0);

    addToRunTimeSelectionTable
    (
        sixDoFRigidBodyMotionRestraint,
        softWall,
        dictionary
    );
}
}


// * * * * * * * * * * * * * * * * Constructors  * * * * * * * * * * * * * * //

Foam::sixDoFRigidBodyMotionRestraints::softWall::softWall
(
    const word& name,
    const dictionary& sDoFRBMRDict
)
:
    sixDoFRigidBodyMotionRestraint(name, sDoFRBMRDict),
    anchor_(Zero),
    refAttachmentPt_(Zero),
    wallNormal_(Zero),
    psi_(0),
    C_(0)
{
    read(sDoFRBMRDict);
}


// * * * * * * * * * * * * * * Member Functions  * * * * * * * * * * * * * * //

void Foam::sixDoFRigidBodyMotionRestraints::softWall::restrain
(
    const sixDoFRigidBodyMotion& motion,
    vector& restraintPosition,
    vector& restraintForce,
    vector& restraintMoment
) const
{
    restraintPosition = motion.transform(refAttachmentPt_);
    restraintForce = Zero;
    restraintMoment = Zero;

    const vector r(restraintPosition - anchor_);

    const vector v(motion.velocity(restraintPosition));

    const scalar d = (wallNormal_/mag(wallNormal_)) & r;

    const vector rDir(r/(mag(r) + VSMALL));

    const scalar m = motion.mass();
    const scalar wn = 3.14/C_;
    const scalar damping = psi_*2*wn*m;
    const scalar stiffness = sqr(wn)*m;

    if (d < 0)
    {
        restraintForce = (-damping*(rDir & v) + stiffness*d)*rDir;
        restraintMoment = restraintPosition^restraintForce;
    }

    if (motion.report())
    {
        Info<< " restraintPosition: " << restraintPosition
            << " restraintForce: " << restraintForce
            << " restraintMoment: " << restraintMoment
            << endl;
    }
}


bool Foam::sixDoFRigidBodyMotionRestraints::softWall::read
(
    const dictionary& sDoFRBMRDict
)
{
    if (!sixDoFRigidBodyMotionRestraint::read(sDoFRBMRDict))
    {
        return false;
    }

    sDoFRBMRCoeffs_.readEntry("anchor", anchor_);
    sDoFRBMRCoeffs_.readEntry("refAttachmentPt", refAttachmentPt_);
    sDoFRBMRCoeffs_.readEntry("wallNormal", wallNormal_);
    sDoFRBMRCoeffs_.readEntry("psi", psi_);
    sDoFRBMRCoeffs_.readEntry("C", C_);

    return true;
}


void Foam::sixDoFRigidBodyMotionRestraints::softWall::write
(
    Ostream& os
) const
{
    os.writeEntry("anchor", anchor_);
    os.writeEntry("refAttachmentPt", refAttachmentPt_);
    os.writeEntry("wallNormal", wallNormal_);
    os.writeEntry("psi", psi_);
    os.writeEntry("C", C_);
}


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