SDA.C

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    Copyright (C) 2020 OpenCFD Ltd.
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#include "SDA.H"
#include "addToRunTimeSelectionTable.H"
#include "mathematicalConstants.H"

using namespace Foam::constant::mathematical;

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

namespace Foam
{
namespace solidBodyMotionFunctions
{
    defineTypeNameAndDebug(SDA, 0);
    addToRunTimeSelectionTable(solidBodyMotionFunction, SDA, dictionary);
}
}


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

Foam::solidBodyMotionFunctions::SDA::SDA
(
    const dictionary& SBMFCoeffs,
    const Time& runTime
)
:
    solidBodyMotionFunction(SBMFCoeffs, runTime),
    CofG_(SBMFCoeffs_.get<vector>("CofG"))
{
    read(SBMFCoeffs);
}


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

Foam::septernion Foam::solidBodyMotionFunctions::SDA::transformation() const
{
    scalar time = time_.value();

    scalar Tpi = Tp_ + dTp_*(time/dTi_);   // Current roll period [sec]
    scalar wr = twoPi/Tpi; // Current Freq [/sec]

    // Current Phase for roll [rad]
    scalar r = dTp_/dTi_;
    scalar u = Tp_ + r*time;
    scalar phr = twoPi*((Tp_/u - 1) + log(mag(u)) - log(Tp_))/r;

    // Current Phase for Sway [rad]
    scalar phs = phr + pi;

    // Current Phase for Heave [rad]
    scalar phh = phr + piByTwo;

    scalar rollA = max(rollAmax_*exp(-sqr(Tpi - Tpn_)/(2*Q_)), rollAmin_);

    vector T
    (
        0,
        swayA_*(sin(wr*time + phs) - sin(phs)),
        heaveA_*(sin(wr*time + phh) - sin(phh))
    );
    quaternion R(quaternion::XYZ, vector(rollA*sin(wr*time + phr), 0, 0));
    septernion TR(septernion(-CofG_ - T)*R*septernion(CofG_));

    DebugInFunction << "Time = " << time << " transformation: " << TR << endl;

    return TR;
}


bool Foam::solidBodyMotionFunctions::SDA::read(const dictionary& SBMFCoeffs)
{
    solidBodyMotionFunction::read(SBMFCoeffs);

    SBMFCoeffs_.readEntry("CofG", CofG_);
    SBMFCoeffs_.readEntry("lamda", lamda_);
    SBMFCoeffs_.readEntry("rollAmax", rollAmax_);
    SBMFCoeffs_.readEntry("rollAmin", rollAmin_);
    SBMFCoeffs_.readEntry("heaveA", heaveA_);
    SBMFCoeffs_.readEntry("swayA", swayA_);
    SBMFCoeffs_.readEntry("Q", Q_);
    SBMFCoeffs_.readEntry("Tp", Tp_);
    SBMFCoeffs_.readEntry("Tpn", Tpn_);
    SBMFCoeffs_.readEntry("dTi", dTi_);
    SBMFCoeffs_.readEntry("dTp", dTp_);

    // Rescale parameters according to the given scale parameter
    if (lamda_ > 1 + SMALL)
    {
        heaveA_ /= lamda_;
        swayA_ /= lamda_;
        Tp_ /= sqrt(lamda_);
        Tpn_ /= sqrt(lamda_);
        dTi_ /= sqrt(lamda_);
        dTp_ /= sqrt(lamda_);
    }

    return true;
}


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