softWall.C

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    Copyright (C) 2019 OpenCFD Ltd.
-------------------------------------------------------------------------------
License
    This file is part of OpenFOAM.
 
    OpenFOAM is free software: you can redistribute it and/or modify it
    under the terms of the GNU General Public License as published by
    the Free Software Foundation, either version 3 of the License, or
    (at your option) any later version.
 
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    ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
    FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License
    for more details.
 
    You should have received a copy of the GNU General Public License
    along with OpenFOAM.  If not, see <http://www.gnu.org/licenses/>.
 
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#include "softWall.H"
#include "rigidBodyModel.H"
#include "addToRunTimeSelectionTable.H"
#include "Time.H"
 
// * * * * * * * * * * * * * * Static Data Members * * * * * * * * * * * * * //
 
namespace Foam
{
namespace RBD
{
namespace restraints
{
    defineTypeNameAndDebug(softWall, 0);
 
    addToRunTimeSelectionTable
    (
        restraint,
        softWall,
        dictionary
    );
}
}
}
 
 
// * * * * * * * * * * * * * * * * Constructors  * * * * * * * * * * * * * * //
 
Foam::RBD::restraints::softWall::softWall
(
    const word& name,
    const dictionary& dict,
    const rigidBodyModel& model
)
:
    restraint(name, dict, model)
{
    read(dict);
}
 
 
// * * * * * * * * * * * * * * * * Destructor  * * * * * * * * * * * * * * * //
 
Foam::RBD::restraints::softWall::~softWall()
{}
 
 
// * * * * * * * * * * * * * * Member Functions  * * * * * * * * * * * * * * //
 
void Foam::RBD::restraints::softWall::restrain
(
    scalarField& tau,
    Field<spatialVector>& fx,
    const rigidBodyModelState& state
) const
{
 
    point p = bodyPoint(refAttachmentPt_);
 
    // Current axis of the spring
    vector r = p - anchor_;
 
    vector force = vector::zero;
    vector moment = vector::zero;
 
    vector v = bodyPointVelocity(refAttachmentPt_).l();
 
    scalar m = model_.bodies()[bodyID_].m();
 
    scalar d = (wallNormal_/mag(wallNormal_)) & r;
 
    vector rDir = r/(mag(r) + VSMALL);
 
    scalar wn =  3.14/C_;
    scalar damping = psi_*2*m*wn;
    scalar stiffness = sqr(wn)*m;
 
    if (d < 0)
    {
        force =
            (-damping*(rDir & v) + stiffness*d)*rDir;
 
        moment = (p ^ force);
    }
 
    if (model_.debug)
    {
        Info<< " stiffness :" << stiffness*d << nl
            << " damping :" << -damping*mag(rDir & v) << nl
            << " force : " << force << nl
            << " d : " << d << nl
            << " r : " << r << nl
            << " p : " << p << nl
            << " velocity : " << v
            << endl;
    }
 
    // Accumulate the force for the restrained body
    fx[bodyIndex_] += spatialVector(moment, force);
}
 
 
bool Foam::RBD::restraints::softWall::read
(
    const dictionary& dict
)
{
    restraint::read(dict);
 
    coeffs_.readEntry("anchor", anchor_);
    coeffs_.readEntry("refAttachmentPt", refAttachmentPt_);
    coeffs_.readEntry("psi", psi_);
    coeffs_.readEntry("C", C_);
    coeffs_.readEntry("wallNormal", wallNormal_);
 
    return true;
}
 
 
void Foam::RBD::restraints::softWall::write
(
    Ostream& os
) const
{
    restraint::write(os);
 
    os.writeEntry("anchor", anchor_);
    os.writeEntry("refAttachmentPt", refAttachmentPt_);
    os.writeEntry("psi", psi_);
    os.writeEntry("C", C_);
    os.writeEntry("wallNormal", wallNormal_);
 
}
 
 
// ************************************************************************* //