SIMPR.C

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/*---------------------------------------------------------------------------*\
  =========                 |
  \\      /  F ield         | OpenFOAM: The Open Source CFD Toolbox
   \\    /   O peration     |
    \\  /    A nd           | www.openfoam.com
     \\/     M anipulation  |
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    Copyright (C) 2011-2016 OpenFOAM Foundation
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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
    along with OpenFOAM.  If not, see <http://www.gnu.org/licenses/>.
 
\*---------------------------------------------------------------------------*/
 
#include "SIBS.H"
 
// * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * //
 
void Foam::SIBS::SIMPR
(
    const scalar xStart,
    const scalarField& y,
    const scalarField& dydx,
    const scalarField& dfdx,
    const scalarSquareMatrix& dfdy,
    const scalar deltaX,
    const label nSteps,
    scalarField& yEnd
) const
{
    scalar h = deltaX/nSteps;
 
    scalarSquareMatrix a(n_);
    for (label i=0; i<n_; i++)
    {
        for (label j=0; j<n_; j++)
        {
            a(i, j) = -h*dfdy(i, j);
        }
        ++a(i, i);
    }
 
    labelList pivotIndices(n_);
    LUDecompose(a, pivotIndices);
 
    for (label i=0; i<n_; i++)
    {
        yEnd[i] = h*(dydx[i] + h*dfdx[i]);
    }
 
    LUBacksubstitute(a, pivotIndices, yEnd);
 
    scalarField del(yEnd);
    scalarField ytemp(n_);
 
    for (label i=0; i<n_; i++)
    {
        ytemp[i] = y[i] + del[i];
    }
 
    scalar x = xStart + h;
 
    odes_.derivatives(x, ytemp, yEnd);
 
    for (label nn=2; nn<=nSteps; nn++)
    {
        for (label i=0; i<n_; i++)
        {
            yEnd[i] = h*yEnd[i] - del[i];
        }
 
        LUBacksubstitute(a, pivotIndices, yEnd);
 
        for (label i=0; i<n_; i++)
        {
            ytemp[i] += (del[i] += 2.0*yEnd[i]);
        }
 
        x += h;
 
        odes_.derivatives(x, ytemp, yEnd);
    }
    for (label i=0; i<n_; i++)
    {
        yEnd[i] = h*yEnd[i] - del[i];
    }
 
    LUBacksubstitute(a, pivotIndices, yEnd);
 
    for (label i=0; i<n_; i++)
    {
        yEnd[i] += ytemp[i];
    }
}
 
 
// ************************************************************************* //