/*---------------------------------------------------------------------------*\
  =========                 |
  \\      /  F ield         | OpenFOAM: The Open Source CFD Toolbox
   \\    /   O peration     |
    \\  /    A nd           | Copyright (C) 2011-2012 OpenFOAM Foundation
     \\/     M anipulation  |
-------------------------------------------------------------------------------
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::variableHeightFlowRateInletVelocityFvPatchVectorField

Group
    grpInletBoundaryConditions

Description
    This boundary condition provides a velocity boundary condition for
    multphase flow based on a user-specified volumetric flow rate.

    The flow rate is made proportional to the phase fraction alpha at each
    face of the patch and alpha is ensured to be bound between 0 and 1.

    \heading Patch usage

    \table
        Property     | Description             | Required    | Default value
        flowRate     | volumetric flow rate [m3/s] | yes |
        alpha        | phase-fraction field    | yes |
    \endtable

    Example of the boundary condition specification:
    \verbatim
    myPatch
    {
        type            variableHeightFlowRateInletVelocity;
        flowRate        0.2;
        alpha           alpha.water;
        value           uniform (0 0 0); // placeholder
    }
    \endverbatim

Note
    - the value is positive into the domain
    - may not work correctly for transonic inlets
    - strange behaviour with potentialFoam since the momentum equation is
      not solved

SeeAlso
    Foam::fixedValueFvPatchField

SourceFiles
    variableHeightFlowRateInletVelocityFvPatchVectorField.C

\*---------------------------------------------------------------------------*/

#ifndef variableHeightFlowRateInletVelocityFvPatchVectorField_H
#define variableHeightFlowRateInletVelocityFvPatchVectorField_H

#include "fixedValueFvPatchFields.H"

// * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * //

namespace Foam
{
/*---------------------------------------------------------------------------*\
    Class variableHeightFlowRateInletVelocityFvPatchVectorField Declaration
\*---------------------------------------------------------------------------*/

class variableHeightFlowRateInletVelocityFvPatchVectorField
:
    public fixedValueFvPatchVectorField
{
    // Private data

        //- Inlet integral flow rate
        scalar flowRate_;

        //- Name of the phase-fraction field
        word alphaName_;


public:

   //- Runtime type information
   TypeName("variableHeightFlowRateInletVelocity");


   // Constructors

        //- Construct from patch and internal field
        variableHeightFlowRateInletVelocityFvPatchVectorField
        (
            const fvPatch&,
            const DimensionedField<vector, volMesh>&
        );

        //- Construct from patch, internal field and dictionary
        variableHeightFlowRateInletVelocityFvPatchVectorField
        (
            const fvPatch&,
            const DimensionedField<vector, volMesh>&,
            const dictionary&
        );

        //- Construct by mapping given
        //  variableHeightFlowRateInletVelocityFvPatchVectorField
        //  onto a new patch
        variableHeightFlowRateInletVelocityFvPatchVectorField
        (
            const variableHeightFlowRateInletVelocityFvPatchVectorField&,
            const fvPatch&,
            const DimensionedField<vector, volMesh>&,
            const fvPatchFieldMapper&
        );

        //- Construct as copy
        variableHeightFlowRateInletVelocityFvPatchVectorField
        (
            const variableHeightFlowRateInletVelocityFvPatchVectorField&
        );

        //- Construct and return a clone
        virtual tmp<fvPatchVectorField> clone() const
        {
            return tmp<fvPatchVectorField>
            (
                new variableHeightFlowRateInletVelocityFvPatchVectorField(*this)
            );
        }

        //- Construct as copy setting internal field reference
        variableHeightFlowRateInletVelocityFvPatchVectorField
        (
            const variableHeightFlowRateInletVelocityFvPatchVectorField&,
            const DimensionedField<vector, volMesh>&
        );

        //- Construct and return a clone setting internal field reference
        virtual tmp<fvPatchVectorField> clone
        (
            const DimensionedField<vector, volMesh>& iF
        ) const
        {
            return tmp<fvPatchVectorField>
            (
                new variableHeightFlowRateInletVelocityFvPatchVectorField
                (
                    *this,
                    iF
                )
            );
        }


    // Member functions

        // Access

            //- Return the flux
            scalar flowRate() const
            {
                return flowRate_;
            }

            //- Return reference to the flux to allow adjustment
            scalar& flowRate()
            {
                return flowRate_;
            }


        //- Update the coefficients associated with the patch field
        virtual void updateCoeffs();

        //- Write
        virtual void write(Ostream&) const;
};


// * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * //

} // End namespace Foam

// * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * //

#endif

// ************************************************************************* //
