symplectic.C

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    Copyright (C) 2015-2016 OpenFOAM Foundation
    Copyright (C) 2023 OpenCFD Ltd.
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#include "symplectic.H"
#include "addToRunTimeSelectionTable.H"

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

namespace Foam
{
namespace sixDoFSolvers
{
    defineTypeNameAndDebug(symplectic, 0);
    addToRunTimeSelectionTable(sixDoFSolver, symplectic, dictionary);
}
}


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

Foam::sixDoFSolvers::symplectic::symplectic
(
    const dictionary& dict,
    sixDoFRigidBodyMotion& body
)
:
    sixDoFSolver(dict, body)
{}


// * * * * * * * * * * * * * * * * Destructor  * * * * * * * * * * * * * * * //

Foam::sixDoFSolvers::symplectic::~symplectic()
{}


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

void Foam::sixDoFSolvers::symplectic::solve
(
    bool firstIter,
    const vector& fGlobal,
    const vector& tauGlobal,
    scalar deltaT,
    scalar deltaT0
)
{
    // First simplectic step:
    //     Half-step for linear and angular velocities
    //     Update position and orientation

    v() = tConstraints() & (v0() + aDamp()*0.5*deltaT0*a0());
    pi() = rConstraints() & (pi0() + aDamp()*0.5*deltaT0*tau0());

    centreOfRotation() = centreOfRotation0() + deltaT*v();

    Tuple2<tensor, vector> Qpi = rotate(Q0(), pi(), deltaT);
    Q() = Qpi.first();
    pi() = rConstraints() & Qpi.second();

    // Update the linear acceleration and torque
    updateAcceleration(fGlobal, tauGlobal);

    // Update the constraints to the object
    updateConstraints();

    // Second simplectic step:
    //     Complete update of linear and angular velocities

    v() += tConstraints() & aDamp()*0.5*deltaT*a();
    pi() += rConstraints() & aDamp()*0.5*deltaT*tau();
}

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