[samanngh]

I simulated a two-phase VOF flow in a microchannel, using interFoam in OpenFOAM v1912, and it produced acceptable results. However, as my goal is the simulation of viscoelastic droplets, I have to use foam extend.

So, when I try to simulate the simpe two-phase Newtonian VOF flow again (as the first step of my project), this time using interFoam in foam extend 4.1, the result differs from my previous attempt with OpenFOAM v1912.


You can see a screenshot of the results here for simulation in OpenFOAM and here for foam-extend.

Can anybody suggest what is going wrong? The constantAlphaContactAngle boundary condition at walls with alpha = 180 is the same in both cases, but the result shows that they are probably not.


It is my alpha1 initial condition:

/*--------------------------------*- C++ -*----------------------------------*\
| =========                 |                                                 |
| \\      /  F ield         | OpenFOAM: The Open Source CFD Toolbox           |
|  \\    /   O peration     | Version:  v1912                                 |
|   \\  /    A nd           | Website:  www.openfoam.com                      |
|    \\/     M anipulation  |                                                 |
\*---------------------------------------------------------------------------*/
FoamFile
{
    version     2.0;
    format      ascii;
    class       volScalarField;
    location    "0";
    object      alpha1;
}
// * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * //

dimensions      [0 0 0 0 0 0 0];

internalField    uniform 0;

boundaryField
{
    inlet
    {
        type            inletOutlet;
        value           uniform 0;
        inletValue      uniform 0;
    }
    outlet1
    {
        type            zeroGradient;
    }
    outlet2
    {
        type            zeroGradient;
    }
    walls
    {
        type            constantAlphaContactAngle;
        theta0          180;
        limit           gradient;
        value           uniform 0;
    }
    frontAndBack
    {
        type            empty;
    }
}

and this is my setFieldDict:

/*--------------------------------*- C++ -*----------------------------------*\
| =========                 |                                                 |
| \\      /  F ield         | OpenFOAM: The Open Source CFD Toolbox           |
|  \\    /   O peration     | Version:  v1912                                 |
|   \\  /    A nd           | Website:  www.openfoam.com                      |
|    \\/     M anipulation  |                                                 |
\*---------------------------------------------------------------------------*/
FoamFile
{
    version     2.0;
    format      ascii;
    class       dictionary;
    location    "system";
    object      setFieldsDict;
}
// * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * //
defaultFieldValues
(
    volScalarFieldValue alpha1 0.0
);

regions
(
    cylinderToCell
    {
        p1 (0.000120 0 -1);
    p2 (0.000120 0 1);
    radius 0.000010;

        fieldValues
        (
            volScalarFieldValue alpha1 1
        );
    }
);
// ************************************************************************* //

Any advice and suggestions will be greatly appreciated. I really have no idea where this problem is arising from.

[samanngh]

I have not solved this problem yet. To ask my question simpler, why I do not get the same result for the constantAlphaContactAngle boundary condition (theta0 = 180) in foam-extend 4.1 as in OpenFOAM v1912.


You can see the difference between two below:


OpenFOAM v1912 result
foam-extend 4.1 result

[HPE]

Hi,

>> Can anybody suggest what is going wrong?

- I think it is likely due to dissimilar implementation of one of the components of the tools you were using for your simulations. And it can be anything really since both OpenFOAM software may have slightly or largely different implementations for the same functionalities.
- Is there any chance for you to compare one of your simulations with an existing benchmark, and proceed from that point?

I'm sorry for not being of good help.

[samanngh]

Originally Posted by HPE

Hi,

>> Can anybody suggest what is going wrong?

- I think it is likely due to dissimilar implementation of one of the components of the tools you were using for your simulations. And it can be anything really since both OpenFOAM software may have slightly or largely different implementations for the same functionalities.
- Is there any chance for you to compare one of your simulations with an existing benchmark, and proceed from that point?

I'm sorry for not being of good help.

>> - Is there any chance for you to compare one of your simulations with an existing benchmark, and proceed from that point?


Many thanks for your consideration.


I know that my result in OpenFOAM v1912 is physically correct, and my result in foam-extend 4.1 is not. However, I have to simulate my project in foam-extend, because I want to use a solver which is only implemented in foam-extend (viscoelasticInterFoam). Thus, I have to get acceptable results in foam-extend too.


It seems there is a bug in interface properties of foam-extend for contact angle = 180, but I do not know how to solve it.

[samanngh]

I've found that foam-extend 4.1 does not use any limitation control on the gradient of alpha1 on the wall, and that's why I do not get desirable results.

I've tried to implement limit control by editing alphaContactAngleFvPatchScalarField.C and alphaContactAngleFvPatchScalarField.H, using these two links as my reference:

https://cpp.openfoam.org/dev/src_2transportModels_2twoPhaseProperties_2alphaCon tactAngle_2alphaContactAngle_2alphaContactAngleFvP atchScalarField_8C_source.html

https://cpp.openfoam.org/dev/src_2tr...8H_source.html

and I obtained these two codes:

/*---------------------------------------------------------------------------*\
  =========                 |
  \\      /  F ield         | foam-extend: Open Source CFD
   \\    /   O peration     | Version:     4.1
    \\  /    A nd           | Web:         http://www.foam-extend.org
     \\/     M anipulation  | For copyright notice see file Copyright
-------------------------------------------------------------------------------
License
    This file is part of foam-extend.

    foam-extend 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.

    foam-extend 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 foam-extend.  If not, see <http://www.gnu.org/licenses/>.

Class
    Foam::alphaContactAngleFvPatchScalarField

Description
    Abstract base class for alphaContactAngle boundary conditions.

    Derived classes must implement the theta() fuction which returns the
    wall contact angle field.

SourceFiles
    alphaContactAngleFvPatchScalarField.C

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

#ifndef alphaContactAngleFvPatchScalarField_H
#define alphaContactAngleFvPatchScalarField_H

#include "fixedGradientFvPatchFields.H"
#include "fvsPatchFields.H"

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

namespace Foam
{

/*---------------------------------------------------------------------------*\
                   Class alphaContactAngleFvPatch Declaration
\*---------------------------------------------------------------------------*/

class alphaContactAngleFvPatchScalarField
:
    public fixedGradientFvPatchScalarField
{

public:

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

    //- Alpha limit options
     enum limitControls
     {
         lcNone,
         lcGradient,
         lcZeroGradient,
         lcAlpha
     };

     static const NamedEnum<limitControls, 4> limitControlNames_;
     limitControls limit_;


    // Constructors

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

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

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

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

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


    // Member functions

        //- Return the contact angle
        virtual tmp<scalarField> theta
        (
            const fvPatchVectorField& Up,
            const fvsPatchVectorField& nHat
        ) const = 0;

        //- Evaluate the patch field
         virtual void evaluate
         (
             const Pstream::commsTypes commsType=Pstream::commsTypes::blocking
         );

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


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

} // End namespace Foam

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

#endif

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

/*---------------------------------------------------------------------------*\
  =========                 |
  \\      /  F ield         | foam-extend: Open Source CFD
   \\    /   O peration     | Version:     4.1
    \\  /    A nd           | Web:         http://www.foam-extend.org
     \\/     M anipulation  | For copyright notice see file Copyright
-------------------------------------------------------------------------------
License
    This file is part of foam-extend.

    foam-extend 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.

    foam-extend 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 foam-extend.  If not, see <http://www.gnu.org/licenses/>.

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

#include "fvPatchFields.H"
#include "alphaContactAngleFvPatchScalarField.H"
#include "addToRunTimeSelectionTable.H"
#include "volMesh.H"

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

namespace Foam
{
    defineTypeNameAndDebug(alphaContactAngleFvPatchScalarField, 0);

    template<>
     const char* Foam::NamedEnum
     <
         Foam::alphaContactAngleFvPatchScalarField::limitControls,
         4
     >::names[] =
     {
         "none",
         "gradient",
         "zeroGradient",
         "alpha"
     };
}

const Foam::NamedEnum
 <
     Foam::alphaContactAngleFvPatchScalarField::limitControls,
     4
 > Foam::alphaContactAngleFvPatchScalarField::limitControlNames_;


// * * * * * * * * * * * * * * * * Constructors  * * * * * * * * * * * * * * //

Foam::alphaContactAngleFvPatchScalarField::alphaContactAngleFvPatchScalarField
(
    const fvPatch& p,
    const DimensionedField<scalar, volMesh>& iF
)
:
    fixedGradientFvPatchScalarField(p, iF),
    limit_(lcZeroGradient)
{}


Foam::alphaContactAngleFvPatchScalarField::alphaContactAngleFvPatchScalarField
(
    const alphaContactAngleFvPatchScalarField& gcpsf,
    const fvPatch& p,
    const DimensionedField<scalar, volMesh>& iF,
    const fvPatchFieldMapper& mapper
)
:
    fixedGradientFvPatchScalarField(gcpsf, p, iF, mapper),
    limit_(gcpsf.limit_)
{}


Foam::alphaContactAngleFvPatchScalarField::alphaContactAngleFvPatchScalarField
(
    const fvPatch& p,
    const DimensionedField<scalar, volMesh>& iF,
    const dictionary& dict
)
:
    fixedGradientFvPatchScalarField(p, iF),
    limit_(limitControlNames_.read(dict.lookup("limit")))
{
    if (dict.found("gradient"))
    {
        gradient() = scalarField("gradient", dict, p.size());
        fixedGradientFvPatchScalarField::updateCoeffs();
        fixedGradientFvPatchScalarField::evaluate();
    }
    else
    {
        fvPatchField<scalar>::operator=(patchInternalField());
        gradient() = 0.0;
    }
}


Foam::alphaContactAngleFvPatchScalarField::alphaContactAngleFvPatchScalarField
(
    const alphaContactAngleFvPatchScalarField& gcpsf
)
:
    fixedGradientFvPatchScalarField(gcpsf),
    limit_(gcpsf.limit_)
{}


Foam::alphaContactAngleFvPatchScalarField::alphaContactAngleFvPatchScalarField
(
    const alphaContactAngleFvPatchScalarField& gcpsf,
    const DimensionedField<scalar, volMesh>& iF
)
:
    fixedGradientFvPatchScalarField(gcpsf, iF),
    limit_(gcpsf.limit_)
{}


  // * * * * * * * * * * * * * * * Member Functions  * * * * * * * * * * * * * //

  void Foam::alphaContactAngleFvPatchScalarField::evaluate
  (
      const Pstream::commsTypes
  )
  {
      if (limit_ == lcGradient)
      {
          gradient() =
          patch().deltaCoeffs()
         *(
             max(min
             (
                 *this + gradient()/patch().deltaCoeffs(),
                 scalar(1)), scalar(0)
             ) - *this
         );
      }
      else if (limit_ == lcZeroGradient)
      {
          gradient() = 0.0;
      }

      fixedGradientFvPatchScalarField::evaluate();

      if (limit_ == lcAlpha)
      {
          scalarField::operator=(max(min(*this, scalar(1)), scalar(0)));
      }
  }


  void Foam::alphaContactAngleFvPatchScalarField::write
  (
      Ostream& os
  ) const
  {
      fixedGradientFvPatchScalarField::write(os);
      writeEntry(os, "limit", limitControlNames_[limit_]);
  }

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

Unfortunately, it doesn't compile successfully. I get this error:

alphaContactAngle/alphaContactAngle/alphaContactAngleFvPatchScalarField.C: In member function ‘virtual void Foam::alphaContactAngleFvPatchScalarField::write(Foam::Ostream&) const’:
alphaContactAngle/alphaContactAngle/alphaContactAngleFvPatchScalarField.C:168:57: error: no matching function for call to ‘Foam::alphaContactAngleFvPatchScalarField::writeEntry(Foam::Ostream&, const char [6], const char*) const’
       writeEntry(os, "limit", limitControlNames_[limit_]);



In file included from /home/saman/foam/foam-extend-4.1/src/foam/lnInclude/labelField.H:39:0,
                 from /home/saman/foam/foam-extend-4.1/src/foam/lnInclude/primitiveFields.H:37,
                 from /home/saman/foam/foam-extend-4.1/src/foam/lnInclude/pointField.H:36,
                 from /home/saman/foam/foam-extend-4.1/src/foam/lnInclude/edge.H:40,
                 from /home/saman/foam/foam-extend-4.1/src/foam/lnInclude/edgeList.H:32,
                 from /home/saman/foam/foam-extend-4.1/src/foam/lnInclude/PrimitivePatchTemplate.H:56,
                 from /home/saman/foam/foam-extend-4.1/src/foam/lnInclude/primitivePatch.H:35,
                 from /home/saman/foam/foam-extend-4.1/src/foam/lnInclude/polyPatch.H:51,
                 from /home/saman/foam/foam-extend-4.1/src/finiteVolume/lnInclude/fvPatch.H:39,
                 from /home/saman/foam/foam-extend-4.1/src/finiteVolume/lnInclude/fvPatchField.H:47,
                 from /home/saman/foam/foam-extend-4.1/src/finiteVolume/lnInclude/fvPatchFields.H:29,
                 from alphaContactAngle/alphaContactAngle/alphaContactAngleFvPatchScalarField.C:26:
/home/saman/foam/foam-extend-4.1/src/foam/lnInclude/Field.H:320:14: note: candidate: void Foam::Field<Type>::writeEntry(const Foam::word&, Foam::Ostream&) const [with Type = double]
         void writeEntry(const word& keyword, Ostream& os) const;
              ^~~~~~~~~~
/home/saman/foam/foam-extend-4.1/src/foam/lnInclude/Field.H:320:14: note:   candidate expects 2 arguments, 3 provided

I tried a couple of things to solve this error but I was not successful. As I am not an expert in C++ and OpenFOAM, can anybody suggest how I should overcome this issue?

[HPE]

Hi,

- Could you please clarify with which OpenFOAM variant do you do compilation: the Foundation or Foam-Extend? The error seems to be arising mixing the two.
- Could you please replace

writeEntry(os, "limit", limitControlNames_[limit_])

with

os.writeEntry("limit", limitControlNames_[limit_]);


Hope it helps.

[samanngh]

I do complitation with Foam-Extend. I replaced 'writeEntry(os, "limit", limitControlNames_[limit_])' with 'os.writeEntry("limit", limitControlNames_[limit_])' and unfortunately, I got this error:

alphaContactAngle/alphaContactAngle/alphaContactAngleFvPatchScalarField.C: In member function ‘virtual void Foam::alphaContactAngleFvPatchScalarField::write(Foam::Ostream&) const’:
alphaContactAngle/alphaContactAngle/alphaContactAngleFvPatchScalarField.C:168:10: error: ‘class Foam::Ostream’ has no member named ‘writeEntry’; did you mean ‘write’?
       os.writeEntry("limit", limitControlNames_[limit_]);
          ^~~~~~~~~~
          write

[HPE]

Hi,

- OK, then can you try:

(limitControlNames_[limit_]).writeEntry("limit", os);

(Sorry, I'm not perfectly educated in foam-extend).

[samanngh]

Sorry for my late reply. I really appreciate your consideration.

I used this command: "os.writeKeyword("limit") << limitControlNames_[limit_] << token::END_STATEMENT << nl;" and then the code compiled without any error. However, the results of my simulation did not change at all! I'm trying to figure out what else could have caused the problem.

[2538sukham]

I am also studying the interface capturing in interFoam. The curvature calculation in foam-extend may be the problem. I am also trying to implement the interFoamSSF which in the forum indicates a better curvature calculation and hence the surface tension calculation. I will post after further studies.