Ramp.H

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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/>.
 
Class
    Foam::Function1s::Ramp
 
Description
    Ramp function base class for the set of scalar functions starting from 0 and
    increasing monotonically to 1 from \c start over the \c duration and
    remaining at 1 thereafter.
 
Usage
    \verbatim
        <name> <rampFunction>;
        <name>Coeffs
        {
            start     10;
            duration  20;
        }
    \endverbatim
    or
    \verbatim
        <name>
        {
            type      <rampFunction>;
            start     10;
            duration  20;
        }
    \endverbatim
    or including a constant scaling factor:
    \verbatim
        <name>
        {
            type      scale;
 
            scale
            {
                type        <rampFunction>;
 
                start       0;
                duration    10;
            }
 
            value       100;
        }
    \endverbatim
    for more details of scaling the ramp see Foam::Function1s::Scale.
 
    Where:
    \table
        Property | Description  | Required | Default value
        start    | Start time   | no       | 0
        duration | Duration     | yes      |
    \endtable
 
See also
    Foam::Function1
    Foam::Function1s::Scale
 
SourceFiles
    Ramp.C
 
\*---------------------------------------------------------------------------*/
 
#ifndef Ramp_H
#define Ramp_H
 
#include "Function1.H"
 
// * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * //
 
namespace Foam
{
namespace Function1s
{
 
/*---------------------------------------------------------------------------*\
                            Class Ramp Declaration
\*---------------------------------------------------------------------------*/
 
template<class Function1Type>
class Ramp
:
    public FieldFunction1<scalar, Function1Type>
{
protected:
 
    // Protected data
 
        //- Start-time of the ramp function
        const scalar start_;
 
        //- Duration of the ramp function
        const scalar duration_;
 
        //- Return the end-time of the ramp function
        inline scalar end() const
        {
            return start_ + duration_;
        }
 
        //- Simple linear ramp function which form the basis of many more
        //  complex ramp functions
        inline scalar linearRamp(const scalar t) const
        {
            return max(min((t - start_)/duration_, 1), 0);
        }
 
        //- The gradient of the linear ramp within the bounds of the ramp
        //  duration
        inline scalar dLinearRampDt() const
        {
            return 1/duration_;
        }
 
 
public:
 
    // Constructors
 
        //- Construct from name and dictionary
        Ramp
        (
            const word& name,
            const unitConversions& units,
            const dictionary& dict
        );
 
 
    //- Destructor
    virtual ~Ramp();
 
 
    // Member Functions
 
        //- Return value for time t
        virtual scalar value(const scalar t) const = 0;
 
        //- Write data to dictionary stream
        virtual void write(Ostream& os, const unitConversions& units) const;
 
 
    // Member Operators
 
        //- Disallow default bitwise assignment
        void operator=(const Ramp<Function1Type>&) = delete;
};
 
 
// * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * //
 
} // End namespace Function1s
} // End namespace Foam
 
// * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * //
 
#ifdef NoRepository
    #include "Ramp.C"
#endif
 
// * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * //
 
#endif
 
// ************************************************************************* //