Newmark.C

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    Copyright (C) 2015-2016 OpenFOAM Foundation
    Copyright (C) 2020-2023 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.
 
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#include "Newmark.H"
#include "addToRunTimeSelectionTable.H"
 
// * * * * * * * * * * * * * * Static Data Members * * * * * * * * * * * * * //
 
namespace Foam
{
namespace sixDoFSolvers
{
    defineTypeNameAndDebug(Newmark, 0);
    addToRunTimeSelectionTable(sixDoFSolver, Newmark, dictionary);
}
}
 
 
// * * * * * * * * * * * * * * * * Constructors  * * * * * * * * * * * * * * //
 
Foam::sixDoFSolvers::Newmark::Newmark
(
    const dictionary& dict,
    sixDoFRigidBodyMotion& body
)
:
    sixDoFSolver(dict, body),
    gamma_(dict.getOrDefault<scalar>("gamma", 0.5)),
    beta_
    (
        max
        (
            0.25*sqr(gamma_ + 0.5),
            dict.getOrDefault<scalar>("beta", 0.25)
        )
    )
{}
 
 
// * * * * * * * * * * * * * * * * Destructor  * * * * * * * * * * * * * * * //
 
Foam::sixDoFSolvers::Newmark::~Newmark()
{}
 
 
// * * * * * * * * * * * * * * * Member Functions  * * * * * * * * * * * * * //
 
void Foam::sixDoFSolvers::Newmark::solve
(
    bool firstIter,
    const vector& fGlobal,
    const vector& tauGlobal,
    scalar deltaT,
    scalar deltaT0
)
{
    // Update the linear acceleration and torque
    updateAcceleration(fGlobal, tauGlobal);
 
    // Update the constraints to the object
    updateConstraints();
 
    // Correct linear velocity
    v() =
        tConstraints()
      & (v0() + aDamp()*deltaT*(gamma_*a() + (1 - gamma_)*a0()));
 
    // Correct angular momentum
    pi() =
        rConstraints()
      & (pi0() + aDamp()*deltaT*(gamma_*tau() + (1 - gamma_)*tau0()));
 
    // Correct position
    centreOfRotation() =
        centreOfRotation0()
      + (
            tConstraints()
          & (
                deltaT*v0()
              + aDamp()*sqr(deltaT)*(beta_*a() + (0.5 - beta_)*a0())
            )
        );
 
    // Correct orientation
    vector piDeltaT =
        rConstraints()
      & (
            deltaT*pi0()
          + aDamp()*sqr(deltaT)*(beta_*tau() + (0.5 - beta_)*tau0())
        );
    Tuple2<tensor, vector> Qpi = rotate(Q0(), piDeltaT, 1);
    Q() = Qpi.first();
}
 
// ************************************************************************* //