EulerSI.H

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-------------------------------------------------------------------------------
    Copyright (C) 2013-2016 OpenFOAM Foundation
    Copyright (C) 2019 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.
 
    OpenFOAM is distributed in the hope that it will be useful, but WITHOUT
    ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
    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/>.
 
Class
    Foam::EulerSI
 
Group
    grpODESolvers
 
Description
    Semi-implicit Euler ODE solver of order (0)1.
 
    The method calculates the new state from:
    \f[
        y_{n+1} = y_n
          + \delta_x\left[I - \delta_x\frac{\partial f}{\partial y}\right]^{-1}
            \cdot \left[f(y_n) + \delta_x\frac{\partial f}{\partial x}\right]
    \f]
    The error is estimated directly from the change in the solution,
    i.e. the difference between the 0th and 1st order solutions:
    \f[
        err_{n+1} = y_{n+1} - y_n
    \f]
 
SourceFiles
    EulerSI.C
 
\*---------------------------------------------------------------------------*/
 
#ifndef EulerSI_H
#define EulerSI_H
 
#include "ODESolver.H"
#include "adaptiveSolver.H"
 
// * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * //
 
namespace Foam
{
 
/*---------------------------------------------------------------------------*\
                           Class EulerSI Declaration
\*---------------------------------------------------------------------------*/
 
class EulerSI
:
    public ODESolver,
    public adaptiveSolver
{
    // Private data
 
        mutable scalarField err_;
        mutable scalarField dydx_;
        mutable scalarField dfdx_;
        mutable scalarSquareMatrix dfdy_;
        mutable scalarSquareMatrix a_;
        mutable labelList pivotIndices_;
 
 
public:
 
    //- Runtime type information
    TypeName("EulerSI");
 
 
    // Constructors
 
        //- Construct from ODESystem
        EulerSI(const ODESystem& ode, const dictionary& dict);
 
 
    //- Destructor
    virtual ~EulerSI() = default;
 
 
    // Member Functions
 
        //- Inherit solve from ODESolver
        using ODESolver::solve;
 
        //- Resize the ODE solver
        virtual bool resize();
 
        //- Solve a single step dx and return the error
        virtual scalar solve
        (
            const scalar x0,
            const scalarField& y0,
            const scalarField& dydx0,
            const scalar dx,
            scalarField& y
        ) const;
 
        //- Solve the ODE system and the update the state
        virtual void solve
        (
            scalar& x,
            scalarField& y,
            scalar& dxTry
        ) const;
};
 
 
// * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * //
 
} // End namespace Foam
 
// * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * //
 
#endif
 
// ************************************************************************* //