SDA.C

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    Copyright (C) 2011-2016 OpenFOAM Foundation
    Copyright (C) 2020 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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    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
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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;
}
 
 
// ************************************************************************* //