Newmark.C

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    Copyright (C) 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 "Newmark.H"
#include "addToRunTimeSelectionTable.H"
 
// * * * * * * * * * * * * * * Static Data Members * * * * * * * * * * * * * //
 
namespace Foam
{
namespace RBD
{
namespace rigidBodySolvers
{
    defineTypeNameAndDebug(Newmark, 0);
    addToRunTimeSelectionTable(rigidBodySolver, Newmark, dictionary);
}
}
}
 
 
// * * * * * * * * * * * * * * * * Constructors  * * * * * * * * * * * * * * //
 
Foam::RBD::rigidBodySolvers::Newmark::Newmark
(
    rigidBodyMotion& body,
    const dictionary& dict
)
:
    rigidBodySolver(body),
    gamma_(dict.getOrDefault<scalar>("gamma", 0.5)),
    beta_
    (
        max
        (
            0.25*sqr(gamma_ + 0.5),
            dict.getOrDefault<scalar>("beta", 0.25)
        )
    )
{}
 
 
// * * * * * * * * * * * * * * * * Destructor  * * * * * * * * * * * * * * * //
 
Foam::RBD::rigidBodySolvers::Newmark::~Newmark()
{}
 
 
// * * * * * * * * * * * * * * * Member Functions  * * * * * * * * * * * * * //
 
void Foam::RBD::rigidBodySolvers::Newmark::solve
(
    const scalarField& tau,
    const Field<spatialVector>& fx
)
{
    // Accumulate the restraint forces
    scalarField rtau(tau);
    Field<spatialVector> rfx(fx);
    model_.applyRestraints(rtau, rfx, state());
 
    // Calculate the accelerations for the given state and forces
    model_.forwardDynamics(state(), rtau, rfx);
 
    // Correct velocity
    qDot() = qDot0()
      + deltaT()*(gamma_*qDdot() + (1 - gamma_)*qDdot0());
 
    // Correct position
    q() = q0()
      + deltaT()*qDot0()
      + sqr(deltaT())*(beta_*qDdot() + (0.5 - beta_)*qDdot0());
 
    correctQuaternionJoints();
}
 
 
// ************************************************************************* //