[Bashar]

Hi,

I was trying for several days to set up the correct BC for my case. I am simulating flow past plate with Re=50000. I am using interFoam to see the effect of free surface on this case. The water level is few centimeters above the pate. Its a 2D simulation with turbulent model using RAS.

I tried several BC based on the tutorial and some suggestion in the forum. Unfortunately, I am doing something wrong, I cant keep the water level at a constant level. After a while all the water will be washed out of the domain. I know it for sure that I made a stupid mistake in the setting but I cant see it.
Attached is my case, if someone have any idea , please let me know.

[Bashar]

Hi,

I managed to get the water level to say at a constant level at the inlet and outlet. Unfortunately, the flow filed is wrong as you can see in the attached figures for the water fraction. Any input will be really appreciated!

Bashar

[Bashar]

and this is the case file

[hiuluom]

On the top boundary you can try total pressure equal to zero for atmosphere instead of symmetry.

[Bashar]

Originally Posted by hiuluom

On the top boundary you can try total pressure equal to zero for atmosphere instead of symmetry.

Do you mean to change the patch type? I am doing the meshing in Fluent , so what should be the type of the patch in Fluent for the upper surface? Can I make it output?


Sent from my iPhone using CFD Online Forum mobile app

[sati]

Hi,

You don't need to change the mesh in Fluent. You can do it with the changeDictionary function.

In your changeDictionaryDict file use something like :

dictionaryReplacement
{
    boundary
        {
            yourPatchName
            {
                    type patch;
            }
        }
}

[Bashar]

Originally Posted by sati

Hi,

You don't need to change the mesh in Fluent. You can do it with the changeDictionary function.

In your changeDictionaryDict file use something like :

dictionaryReplacement
{
    boundary
        {
            yourPatchName
            {
                    type patch;
            }
        }
}

Thanks a lot , I never used or heard about this before ! Sorry still learning , I will read about this.


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[Bashar]

Hi,
I run the case at my spare time with different BC combination using the help of others user and the several suggestions on this website. I still didn't get a correct physical results. The behavior at this moment is much better from the starting point, however this time the water level don't stay constant. Its increasing with time.
Below the BC I used.

/*--------------------------------*- C++ -*----------------------------------*\
| =========                 |                                                 |
| \\      /  F ield         | OpenFOAM: The Open Source CFD Toolbox           |
|  \\    /   O peration     | Version:  3.0.1                                 |
|   \\  /    A nd           | Web:      www.OpenFOAM.org                      |
|    \\/     M anipulation  |                                                 |
\*---------------------------------------------------------------------------*/
FoamFile
{
    version     2.0;
    format      ascii;
    class       volScalarField;
    location    "0";
    object      alpha;
}
// * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * //

dimensions      [0 0 0 0 0 0 0];

internalField   uniform 0;

boundaryField
{
    inlet
    {


    type            groovyBC;
    variables    "yp=pos().y;";
    valueExpression "(yp>0.11) ? 1 : 0";
        value           uniform 1;

    }

    outlet
    {
        type            zeroGradient;
/*
        type            variableHeightFlowRate;
        lowerBound      0;
        upperBound      1;
        value           $internalField;
*/
    }

    plate
    {
        type            zeroGradient;
    }

    top
    {
        type            slip;
    }

    bottom
    {
        type            slip;
    }

    frontAndBackPlanes
    {
        type            empty;
    }
}


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

/*--------------------------------*- C++ -*----------------------------------*\
| =========                 |                                                 |
| \\      /  F ield         | OpenFOAM: The Open Source CFD Toolbox           |
|  \\    /   O peration     | Version:  3.0.1                                 |
|   \\  /    A nd           | Web:      www.OpenFOAM.org                      |
|    \\/     M anipulation  |                                                 |
\*---------------------------------------------------------------------------*/
FoamFile
{
    version     2.0;
    format      ascii;
    class       volVectorField;
    location    "0";
    object      U;
}
// * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * //
dimensions      [0 1 -1 0 0 0 0];

internalField   uniform (0 0 0);

boundaryField
{
    inlet
    {
    type            groovyBC;
    variables    "yp=pos().y;Ux=((yp>0.11) ? 0.01 : 0.5);";
    valueExpression "vector(Ux,0,0)";
        value           uniform (0 0 0);
    }

    outlet
    {
      type            zeroGradient;
    }

    plate
    {
        type            fixedValue;
        value           uniform (0 0 0);
    }

    top
    {
        type            slip;
    }

    bottom
    {
        type            slip;
    }

    frontAndBackPlanes
    {
        type            empty;
    }
}


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

/*--------------------------------*- C++ -*----------------------------------*\
| =========                 |                                                 |
| \\      /  F ield         | OpenFOAM: The Open Source CFD Toolbox           |
|  \\    /   O peration     | Version:  3.0.1                                 |
|   \\  /    A nd           | Web:      www.OpenFOAM.org                      |
|    \\/     M anipulation  |                                                 |
\*---------------------------------------------------------------------------*/
FoamFile
{
    version     2.0;
    format      ascii;
    class       volScalarField;
    location    "0";
    object      p_rgh;
}
// * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * //

dimensions      [1 -1 -2 0 0 0 0];

internalField   uniform 0;

boundaryField
{
    inlet
    {
         type       fixedFluxPressure;
         value      uniform 0;
    }

    outlet
    {

        type            zeroGradient;
 
    }


    plate
    {

       type            fixedFluxPressure;
       value           uniform 0;//$internalField;

    }

    
    top
    {
        type            slip;

    }


    bottom
    {
        type            slip;
    }

    frontAndBackPlanes
    {
        type            empty;
    }
}

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

/*--------------------------------*- C++ -*----------------------------------*\
| =========                 |                                                 |
| \\      /  F ield         | OpenFOAM: The Open Source CFD Toolbox           |
|  \\    /   O peration     | Version:  3.0.1                                 |
|   \\  /    A nd           | Web:      www.OpenFOAM.org                      |
|    \\/     M anipulation  |                                                 |
\*---------------------------------------------------------------------------*/
FoamFile
{
    version     2.0;
    format      ascii;
    class       volScalarField;
    location    "0";
    object      omega;
}
// * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * //

dimensions      [0 0 -1 0 0 0 0];

internalField   uniform 0.25;

boundaryField
{
    inlet
    {
        type            fixedValue;
        value           uniform 0.25;
    }

    outlet
    {
        type            zeroGradient;
    }

    plate
    {
        type            omegaWallFunction;
        value           uniform 0.25;
    }

    top
    {
        type            slip;
    }

    bottom
    {
        type            slip;
    }

    frontAndBackPlanes
    {
        type            empty;
    }
}


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

/*--------------------------------*- C++ -*----------------------------------*\
| =========                 |                                                 |
| \\      /  F ield         | OpenFOAM: The Open Source CFD Toolbox           |
|  \\    /   O peration     | Version:  3.0.1                                 |
|   \\  /    A nd           | Web:      www.OpenFOAM.org                      |
|    \\/     M anipulation  |                                                 |
\*---------------------------------------------------------------------------*/
FoamFile
{
    version     2.0;
    format      ascii;
    class       volScalarField;
    location    "0";
    object      k;
}
// * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * //

dimensions      [0 2 -2 0 0 0 0];

internalField   uniform 6e-4; //Estimated for T.I. = 4%

boundaryField
{
    inlet
    {
        type            fixedValue;
        value           uniform 0.0006;
    }

    outlet
    {
        type            zeroGradient;
    }

    plate
    {
        type            kqRWallFunction;
        value           uniform 0.0006;
    }

    top
    {
        type            slip;
    }

    bottom
    {
        type            slip;
    }

    frontAndBackPlanes
    {
        type            empty;
    }
}


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

Any help is really appreciated.

[ssmeherk]

Bashar,

Your top boundary cannot be slip. It should reflect atmospheric boundary conditions which was already suggested by others.

You can refer to boundary conditions of ATMOSPHERE boundary in the below thread if you find any difficulty:
Free surface flow in a channel: how to maintain water level
Also, please correct the direction of gravity in g file.

Meher.

[Bashar]

Originally Posted by ssmeherk

Bashar,

Your top boundary cannot be slip. It should reflect atmospheric boundary conditions which was already suggested by others.

You can refer to boundary conditions of ATMOSPHERE boundary in the below thread if you find any difficulty:
Free surface flow in a channel: how to maintain water level
Also, please correct the direction of gravity in g file.

Meher.

Thanks again Meher,
Unfortunately, I did this but with no luck! The behavior is not like the first pictures, but the water is going below the plate , and the surface is very disturbed. So, in short changing the top BC from wall to atmosphere didn't work.



Sent from my iPhone using CFD Online Forum mobile app

[Bashar]

Also Meher , what about the g? I am using it to be in the negative y direction , since my 2D plane is xy. Is this wrong?

Thank you
Bashar


Sent from my iPhone using CFD Online Forum mobile app

[ssmeherk]

Bashar,

My comments are based on what you have posted so far.

My understanding of a free surface flow problem says that a top boundary should be reflecting atmospheric conditions which I cannot see in any of your previous posts.

Same is the case with g. Both the case files you shared indicate negative z direction but not negative y.

It's good that you already tried these changes. But it would be better if you post the exact case file along with mesh to rightly understand and help you out.

Thank you

Meher

[Bashar]

Originally Posted by ssmeherk

Bashar,

My comments are based on what you have posted so far.

My understanding of a free surface flow problem says that a top boundary should be reflecting atmospheric conditions which I cannot see in any of your previous post.

Same is the case with g. Both the case files you shared indicate negative z direction but not negative y.

It's good that you already tried these changes. But it would be better if you post the exact case file along with mesh to rightly understand and help you out.

Thank you

Meher

Hi,

Thanks a lot Meher for your answer . I am sorry I didn't put the updated case files , I only put the the codes for the BC in the previous post #8 . Attached is the result of the checkMesh:

/*---------------------------------------------------------------------------*\
| =========                 |                                                 |
| \\      /  F ield         | OpenFOAM: The Open Source CFD Toolbox           |
|  \\    /   O peration     | Version:  3.0.1                                 |
|   \\  /    A nd           | Web:      www.OpenFOAM.org                      |
|    \\/     M anipulation  |                                                 |
\*---------------------------------------------------------------------------*/
Build  : 3.0.1-119cac7e8750
Exec   : checkMesh
Date   : Mar 29 2017
Time   : 15:06:03
Host   : "basharhpc"
PID    : 21894
Case   : /home/bashar/OpenFOAM/bashar-3.0.1/run/1_Corrected
nProcs : 1
sigFpe : Enabling floating point exception trapping (FOAM_SIGFPE).
fileModificationChecking : Monitoring run-time modified files using timeStampMaster
allowSystemOperations : Allowing user-supplied system call operations

// * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * //
Create time

Create polyMesh for time = 0

Time = 0

Mesh stats
    points:           342640
    internal points:  0
    faces:            682820
    internal faces:   340180
    cells:            170500
    faces per cell:   6
    boundary patches: 6
    point zones:      0
    face zones:       0
    cell zones:       0

Overall number of cells of each type:
    hexahedra:     170500
    prisms:        0
    wedges:        0
    pyramids:      0
    tet wedges:    0
    tetrahedra:    0
    polyhedra:     0

Checking topology...
    Boundary definition OK.
    Cell to face addressing OK.
    Point usage OK.
    Upper triangular ordering OK.
    Face vertices OK.
    Number of regions: 1 (OK).

Checking patch topology for multiply connected surfaces...
    Patch               Faces    Points   Surface topology                  
    bottom              410      822      ok (non-closed singly connected)  
    plate               480      960      ok (non-closed singly connected)  
    outlet              170      342      ok (non-closed singly connected)  
    top                 410      822      ok (non-closed singly connected)  
    inlet               170      342      ok (non-closed singly connected)  
    frontAndBackPlanes  341000   342640   ok (non-closed singly connected)  

Checking geometry...
    Overall domain bounding box (-2 -0.8 -0.05) (2.5 1.3 0.05)
    Mesh has 2 geometric (non-empty/wedge) directions (1 1 0)
    Mesh has 2 solution (non-empty) directions (1 1 0)
    All edges aligned with or perpendicular to non-empty directions.
    Boundary openness (1.47846e-18 3.52794e-17 -5.32995e-19) OK.
    Max cell openness = 3.04874e-16 OK.
    Max aspect ratio = 4.30387 OK.
    Minimum face area = 1.52097e-08. Maximum face area = 0.00133333.  Face area magnitudes OK.
    Min volume = 1.52097e-09. Max volume = 1.33333e-05.  Total volume = 0.944901.  Cell volumes OK.
    Mesh non-orthogonality Max: 46.429 average: 23.0163
    Non-orthogonality check OK.
    Face pyramids OK.
    Max skewness = 2.62783 OK.
    Coupled point location match (average 0) OK.

Mesh OK.

The mesh file is large since I converted it from fluent.
Sorry again for the confusion, and for not providing good descriptions .
Bashar

[Bashar]

This is also the updated case. I am currently running this case, I am trying different combination of BC to see the effect. Please if you can give me your opinion regarding the setting. Many thanks.

Bashar

[Phicau]

Hi Bashar,

you can try with olaFoam ( https://github.com/phicau/OLAFOAM ), there is a tutorial named currentWaveFlume that is very close to what you want. It should be very easy for you to modify it to include the airfoil.

Best,

Pablo

[Bashar]

Originally Posted by Phicau

Hi Bashar,

you can try with olaFoam ( https://github.com/phicau/OLAFOAM ), there is a tutorial named currentWaveFlume that is very close to what you want. It should be very easy for you to modify it to include the airfoil.

Best,

Pablo

Thank you Pablo,

So , will this work under openFoam? or do I need to work in different software?
Regards,
Bashar

[Phicau]

Yes, you need OpenFOAM to run olaFoam, because the wave/current generation modules are an extension of OpenFOAM.

Best,

Pablo

[Bashar]

Originally Posted by Phicau

Yes, you need OpenFOAM to run olaFoam, because the wave/current generation modules are an extension of OpenFOAM.

Best,

Pablo

Thanks again Pablo. I read some details and your work is interesting. At this point I will stay with my openFoam standard version, I am still new to openFoam and I want to learn using it first before going to additional solvers and customized models. Thanks again for the suggestions and you really did an impressive work.
Best wishes ,
Bashar

[ssmeherk]

Bashar,

Any particular reason for configuring your case setup w.r.t alpha.air rather than using alpha.water ?

Most of the interFoam tutorials use alpha.water. You may be right (I did not check thoroughly) but I prefer the conventional way as per tutorials.

In setFieldsDict file, please check the dimensions once again. There is a mismatch with your bounding box dimensions (especially z dimensions) from checkMesh.

Also, is it really necessary to explicitly specify volume fractions at inlet boundary in alpha.air file using groovy boundary condition ?

Since you are already configuring the case with setFieldsDict, a zeroGradient boundary condition should suffice.

Meher.

[Bashar]

Originally Posted by ssmeherk

Bashar,

Any particular reason for configuring your case setup w.r.t alpha.air rather than using alpha.water ?

Most of the interFoam tutorials use alpha.water. You may be right (I did not check thoroughly) but I prefer the conventional way as per tutorials.

In setFieldsDict file, please check the dimensions once again. There is a mismatch with your bounding box dimensions (especially z dimensions) from checkMesh.

Also, is it really necessary to explicitly specify volume fractions at inlet boundary in alpha.air file using groovy boundary condition ?

Since you are already configuring the case with setFieldsDict, a zeroGradient boundary condition should suffice.

Meher.

Hi, and many thanks again for your input. Regarding the alpha configuration , I am trying to do the case in this paper. They used the air as the primary phase , thats why I choose the air for configuration. I am not sure if this is necessary or not?
http://www.sciencedirect.com/science...29801815006228

Also, regarding the mismatch in the mesh, I am fixing this using makeMesh to make to z direction 0.1 but I think I made a mistake, so I will correct this and run it again.
When it comes to groovey BC , in the previous paper that I mentioned they have two different speed of air and water. For air they have 0.01 and for water 0.5 m/sec, thats why the use of groovey BC, other wise I think I need to do a new mesh with different inlet patch one for air and the other for water. I will test your suggestion to use zerogradient at the inlet but what should I use for the outlet?


I mentioned early #14 that I run the case again with the attached BC in the previous zip file. Unfortunately, it runs only one second after that I have this message , with floating point:

PIMPLE: iteration 1
smoothSolver:  Solving for alpha.air, Initial residual = 0.00021203, Final residual = 5.58644e-07, No Iterations 1
Phase-1 volume fraction = 0.498669  Min(alpha.air) = 0  Max(alpha.air) = 1.00001
MULES: Correcting alpha.air
MULES: Correcting alpha.air
Phase-1 volume fraction = 0.498669  Min(alpha.air) = 0  Max(alpha.air) = 1.00065
[2] #0  Foam::error::printStack(Foam::Ostream&) at ??:?
[2] #1  Foam::sigFpe::sigHandler(int) at ??:?
[2] #2  ? in "/lib/x86_64-linux-gnu/libc.so.6"
[2] #3  Foam::GAMGSolver::scale(Foam::Field<double>&, Foam::Field<double>&, Foam::lduMatrix const&, Foam::FieldField<Foam::Field, double> const&, Foam::UPtrList<Foam::lduInterfaceField const> const&, Foam::Field<double> const&, unsigned char) const at ??:?
[2] #4  Foam::GAMGSolver::Vcycle(Foam::PtrList<Foam::lduMatrix::smoother> const&, Foam::Field<double>&, Foam::Field<double> const&, Foam::Field<double>&, Foam::Field<double>&, Foam::Field<double>&, Foam::Field<double>&, Foam::Field<double>&, Foam::PtrList<Foam::Field<double> >&, Foam::PtrList<Foam::Field<double> >&, unsigned char) const at ??:?
[2] #5  Foam::GAMGSolver::solve(Foam::Field<double>&, Foam::Field<double> const&, unsigned char) const at ??:?
[2] #6  Foam::fvMatrix<double>::solveSegregated(Foam::dictionary const&) at ??:?
[2] #7  Foam::fvMatrix<double>::solve(Foam::dictionary const&) at ??:?
[2] #8  ? at ??:?
[2] #9  __libc_start_main in "/lib/x86_64-linux-gnu/libc.so.6"
[2] #10  ? at ??:?
[basharhpc:30594] *** Process received signal ***
[basharhpc:30594] Signal: Floating point exception (8)
[basharhpc:30594] Signal code:  (-6)
[basharhpc:30594] Failing at address: 0x3e800007782
[basharhpc:30594] [ 0] /lib/x86_64-linux-gnu/libc.so.6(+0x35250) [0x7f55331fc250]
[basharhpc:30594] [ 1] /lib/x86_64-linux-gnu/libc.so.6(gsignal+0x37) [0x7f55331fc1c7]
[basharhpc:30594] [ 2] /lib/x86_64-linux-gnu/libc.so.6(+0x35250) [0x7f55331fc250]
[basharhpc:30594] [ 3] /opt/openfoam30/platforms/linux64GccDPInt32Opt/lib/libOpenFOAM.so(_ZNK4Foam10GAMGSolver5scaleERNS_5FieldIdEES3_RKNS_9lduMatrixERKNS_10FieldFieldIS1_dEERKNS_8UPtrListIKNS_17lduInterfaceFieldEEERKS2_h+0xb1) [0x7f55344541c1]
[basharhpc:30594] [ 4] /opt/openfoam30/platforms/linux64GccDPInt32Opt/lib/libOpenFOAM.so(_ZNK4Foam10GAMGSolver6VcycleERKNS_7PtrListINS_9lduMatrix8smootherEEERNS_5FieldIdEERKS8_S9_S9_S9_S9_S9_RNS1_IS8_EESD_h+0x783) [0x7f5534457073]
[basharhpc:30594] [ 5] /opt/openfoam30/platforms/linux64GccDPInt32Opt/lib/libOpenFOAM.so(_ZNK4Foam10GAMGSolver5solveERNS_5FieldIdEERKS2_h+0x671) [0x7f5534459d21]
[basharhpc:30594] [ 6] /opt/openfoam30/platforms/linux64GccDPInt32Opt/lib/libfiniteVolume.so(_ZN4Foam8fvMatrixIdE15solveSegregatedERKNS_10dictionaryE+0x16c) [0x7f553631f1ec]
[basharhpc:30594] [ 7] interFoam(_ZN4Foam8fvMatrixIdE5solveERKNS_10dictionaryE+0x199) [0x487479]
[basharhpc:30594] [ 8] interFoam() [0x43208a]
[basharhpc:30594] [ 9] /lib/x86_64-linux-gnu/libc.so.6(__libc_start_main+0xf0) [0x7f55331e7ac0]
[basharhpc:30594] [10] interFoam() [0x4390b9]
[basharhpc:30594] *** End of error message ***
--------------------------------------------------------------------------
mpirun noticed that process rank 2 with PID 30594 on node basharhpc exited on signal 8 (Floating point exception).
--------------------------------------------------------------------------
Running reconstructPar on /home/bashar/OpenFOAM/bashar-3.0.1/run/2d_vof

Regards,
Bashar