HerschelBulkley.H

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License
    This file is part of OpenFOAM.
 
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Class
    Foam::laminarModels::generalisedNewtonianViscosityModels::HerschelBulkley
 
Description
    Herschel-Bulkley generalised Newtonian viscosity model
 
    The Herschel-Bulkley model combines the effects of a Bingham plastic
    and power-law behaviour of a fluid. At a low strain rate \f$\gamma\f$
    the fluid adopts a viscosity \f$\nu_0\f$. Beyond a threshold stress
    \f$\tau_0\f$, the viscosity is described as a power law.
 
    Kinematic viscosity [m^2/s]
 
    \f[
        \nu = \min(\nu_0, \tau_0/\gamma + k\gamma^{n - 1})
    \f]
 
    Example specification:
    \verbatim
         viscosityModel HerschelBulkley;
 
         tau0       0.01;
         k          0.001;
         n          0.2;
    \endverbatim
 
    Note the viscosity \c nu0 at zero strain rate is a physical property,
    generally specified in the physicalProperties file.
 
SourceFiles
    HerschelBulkley.C
 
\*---------------------------------------------------------------------------*/
 
#ifndef HerschelBulkley_H
#define HerschelBulkley_H
 
#include "strainRateViscosityModel.H"
 
// * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * //
 
namespace Foam
{
namespace laminarModels
{
namespace generalisedNewtonianViscosityModels
{
 
/*---------------------------------------------------------------------------*\
                       Class HerschelBulkley Declaration
\*---------------------------------------------------------------------------*/
 
class HerschelBulkley
:
    public strainRateViscosityModel
{
    // Private Data
 
        dimensionedScalar k_;
        dimensionedScalar n_;
        dimensionedScalar tau0_;
 
 
public:
 
    //- Runtime type information
    TypeName("HerschelBulkley");
 
 
    // Constructors
 
        //- Construct from components
        HerschelBulkley
        (
            const dictionary& viscosityProperties,
            const Foam::viscosity& viscosity,
            const volVectorField& U
        );
 
 
    //- Destructor
    virtual ~HerschelBulkley()
    {}
 
 
    // Member Functions
 
        //- Read transportProperties dictionary
        virtual bool read(const dictionary& viscosityProperties);
 
        //- Return the laminar viscosity
        virtual tmp<volScalarField> nu
        (
            const volScalarField& nu0,
            const volScalarField& strainRate
        ) const;
};
 
 
// * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * //
 
} // End namespace generalisedNewtonianViscosityModels
} // End namespace laminarModels
} // End namespace Foam
 
// * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * //
 
#endif
 
// ************************************************************************* //