symplectic.C

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/*---------------------------------------------------------------------------*\
  =========                 |
  \\      /  F ield         | OpenFOAM: The Open Source CFD Toolbox
   \\    /   O peration     |
    \\  /    A nd           | Copyright (C) 2015 OpenFOAM Foundation
     \\/     M anipulation  |
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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(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
)
{
    if (!firstIter)
    {
        FatalErrorInFunction
            << "The symplectic integrator is explicit "
               "and can only be solved once per time-step"
            << exit(FatalError);
    }
 
    // 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);
 
    // Second simplectic step:
    //     Complete update of linear and angular velocities
 
    v() += tConstraints() & aDamp()*0.5*deltaT*a();
    pi() += rConstraints() & aDamp()*0.5*deltaT*tau();
}
 
 
// ************************************************************************* //