Residuals blowing up for simple turbulent case

ss32 · April 16, 2016, 22:57

I am attempting to model turbulent flow over a cylinder. I created an unstructured mesh in pointwise and imported into openFoam. The geometry is dead simple: A sqaure boundary around a circle.

Boundary Conditions:
Circle - wall
top/bottom (y-axis) front/back (z-axis) - empty
front/back (x-axis) - patch

I have set the front (x-axis) as an inlet and back (x-axis) as outlet and am solving using k-epsilon. The domain is 10 x 10 with the circle being 1 in diameter.

0 directory, all files modified versions of pitzDaily example:

epsilon

Code:

/*--------------------------------*- C++ -*----------------------------------*\
| =========                 |                                                 |
| \\      /  F ield         | OpenFOAM: The Open Source CFD Toolbox           |
|  \\    /   O peration     | Version:  v3.0+                                 |
|   \\  /    A nd           | Web:      www.OpenFOAM.com                      |
|    \\/     M anipulation  |                                                 |
\*---------------------------------------------------------------------------*/
FoamFile
{
    version     2.0;
    format      ascii;
    class       volScalarField;
    location    "0";
    object      epsilon;
}
// * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * //

dimensions      [0 2 -3 0 0 0 0];

internalField   uniform 0.00335;

boundaryField
{
    frontback
    {
        type            empty;
    }
    inlet
    {
        type            fixedValue;
        value           uniform 0.00335;
    }
    outlet
    {
        type            zeroGradient;
    }

    walls
    {
        type            epsilonWallFunction;
        value           uniform 0.00335;
    }

}


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

U

Code:

/*--------------------------------*- C++ -*----------------------------------*\
| =========                 |                                                 |
| \\      /  F ield         | OpenFOAM: The Open Source CFD Toolbox           |
|  \\    /   O peration     | Version:  v3.0+                                 |
|   \\  /    A nd           | Web:      www.OpenFOAM.com                      |
|    \\/     M anipulation  |                                                 |
\*---------------------------------------------------------------------------*/
FoamFile
{
    version     2.0;
    format      ascii;
    class       volVectorField;
    object      U;
}
// * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * //

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

internalField   uniform (3 0 0);

boundaryField
{
    frontback
    {
        type            empty;
    }
    inlet
    {
        type            fixedValue;
        value           uniform (3 0 0);
    }

    outlet
    {
        type            zeroGradient;
    }

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

}

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

nut

Code:

/*--------------------------------*- C++ -*----------------------------------*\
| =========                 |                                                 |
| \\      /  F ield         | OpenFOAM: The Open Source CFD Toolbox           |
|  \\    /   O peration     | Version:  v3.0+                                 |
|   \\  /    A nd           | Web:      www.OpenFOAM.com                      |
|    \\/     M anipulation  |                                                 |
\*---------------------------------------------------------------------------*/
FoamFile
{
    version     2.0;
    format      ascii;
    class       volScalarField;
    location    "0";
    object      nut;
}
// * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * //

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

internalField   uniform 0;

boundaryField
{
    frontback
    {
        type            empty;
    }
    inlet
    {
        type            calculated;
        value           uniform 0;
    }
    outlet
    {
        type            calculated;
        value           uniform 0;
    }

    walls
    {
        type            nutkWallFunction;
        value           uniform 0;
    }
}


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

nuTilda

Code:

/*--------------------------------*- C++ -*----------------------------------*\
| =========                 |                                                 |
| \\      /  F ield         | OpenFOAM: The Open Source CFD Toolbox           |
|  \\    /   O peration     | Version:  v3.0+                                 |
|   \\  /    A nd           | Web:      www.OpenFOAM.com                      |
|    \\/     M anipulation  |                                                 |
\*---------------------------------------------------------------------------*/
FoamFile
{
    version     2.0;
    format      ascii;
    class       volScalarField;
    object      nuTilda;
}
// * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * //

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

internalField   uniform 0;

boundaryField
{
    frontback
    {
        type            empty;
    }

    inlet
    {
        type            fixedValue;
        value           uniform 0;
    }

    outlet
    {
        type            zeroGradient;
    }


    walls
    {
        type            zeroGradient;
    }

}

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

k

Code:

/*--------------------------------*- C++ -*----------------------------------*\
| =========                 |                                                 |
| \\      /  F ield         | OpenFOAM: The Open Source CFD Toolbox           |
|  \\    /   O peration     | Version:  v3.0+                                 |
|   \\  /    A nd           | Web:      www.OpenFOAM.com                      |
|    \\/     M anipulation  |                                                 |
\*---------------------------------------------------------------------------*/
FoamFile
{
    version     2.0;
    format      ascii;
    class       volScalarField;
    location    "0";
    object      k;
}
// * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * //

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

internalField   uniform 0.00555;

boundaryField
{
    frontback
    {
        type            empty;

    }
    inlet
    {
        type            fixedValue;
        value           uniform 0.00555;
    }
    outlet
    {
        type            zeroGradient;
    }

    walls
    {
        type            kqRWallFunction;
        value           uniform 0.00555;
    }

}


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

p

Code:

/*--------------------------------*- C++ -*----------------------------------*\
| =========                 |                                                 |
| \\      /  F ield         | OpenFOAM: The Open Source CFD Toolbox           |
|  \\    /   O peration     | Version:  v3.0+                                 |
|   \\  /    A nd           | Web:      www.OpenFOAM.com                      |
|    \\/     M anipulation  |                                                 |
\*---------------------------------------------------------------------------*/
FoamFile
{
    version     2.0;
    format      ascii;
    class       volScalarField;
    object      p;
}
// * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * //

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

internalField   uniform 0;

boundaryField
{
    frontback
    {
        type            empty;
    }

    inlet
    {
        type            zeroGradient;
    }

    outlet
    {
        type            fixedValue;
        value           uniform 0;
    }


    walls
    {
        type            zeroGradient;
    }


}

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

The case fails on the first time step with infinite residuals and I'm lost as to why.

Code:

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

Create mesh for time = 0


SIMPLE: convergence criteria
    field p     tolerance 1e-08
    field U     tolerance 1e-08
    field "(k|epsilon|omega|f|v2)"     tolerance 0.001

Reading field p

Reading field U

Reading/calculating face flux field phi

Selecting incompressible transport model Newtonian
Selecting turbulence model type RAS
Selecting RAS turbulence model kEpsilon
kEpsilonCoeffs
{
    Cmu             0.09;
    C1              1.44;
    C2              1.92;
    C3              -0.33;
    sigmak          1;
    sigmaEps        1.3;
}

No MRF models present

No finite volume options present


Starting time loop

streamLine streamLines:
    automatic track length specified through number of sub cycles : 5

Time = 0.0001

smoothSolver:  Solving for Ux, Initial residual = 1, Final residual = nan, No Iterations 1000
GAMG:  Solving for p, Initial residual = nan, Final residual = nan, No Iterations 1000
GAMG:  Solving for p, Initial residual = nan, Final residual = nan, No Iterations 1000


--> FOAM FATAL IO ERROR: 
wrong token type - expected Scalar, found on line 0 the word 'nan'

ss32 · April 17, 2016, 11:14

I have changed the top/bottom to patch and assigned them freestream values, still getting the same problem.

tomf · April 18, 2016, 06:59

It looks like you are only solving for Ux, which means you are solving for a 1D problem. Please run checkMesh and make sure you have defined your problem correctly.

ss32 · April 18, 2016, 09:37

Quote:

Originally Posted by tomf

It looks like you are only solving for Ux, which means you are solving for a 1D problem. Please run checkMesh and make sure you have defined your problem correctly.

Everything looks good, but how do I ensure I'm solving a 2D problem?

Code:

Create time

Create polyMesh for time = 0

Time = 0

Mesh stats
    points:           42006
    internal points:  0
    faces:            142845
    internal faces:   60225
    cells:            40614
    faces per cell:   5
    boundary patches: 5
    point zones:      0
    face zones:       0
    cell zones:       0

Overall number of cells of each type:
    hexahedra:     0
    prisms:        40614
    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
    frontback           81228    42006    ok (non-closed singly connected)
    inlet               398      798      ok (non-closed singly connected)
    outlet              398      798      ok (non-closed singly connected)
    topbottom           398      800      ok (non-closed singly connected)
    walls               198      396      ok (non-closed singly connected)

Checking geometry...
    Overall domain bounding box (-5 -5 0.01) (5 5 0.02)
    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 (-1.87618e-18 -1.46651e-20 6.08114e-16) OK.
    Max cell openness = 2.42378e-16 OK.
    Max aspect ratio = 6.56347 OK.
    Minimum face area = 5.01428e-05. Maximum face area = 0.0059415.  Face area magnitudes OK.
    Min volume = 5.01428e-07. Max volume = 5.9415e-05.  Total volume = 0.992154.  Cell volumes OK.
    Mesh non-orthogonality Max: 51.6706 average: 8.27031
    Non-orthogonality check OK.
    Face pyramids OK.
    Max skewness = 0.732464 OK.
    Coupled point location match (average 0) OK.

Mesh OK.

End

tomf · April 18, 2016, 09:49

I take this from your first post

Quote:

Boundary Conditions:
Circle - wall
top/bottom (y-axis) front/back (z-axis) - empty
front/back (x-axis) - patch

Which would explain why it is not solving for Uy and Uz: both are empty.

However you claim to have used freestream for topbottom (redefined as type patch) as well and got the same result? Where did you change the patch type? It should be in constant/polyMesh/boundary.

The topbottom is also not mentioned in your boundary conditions from your first post.

Regards,
Tom

ss32 · April 18, 2016, 11:23

I went into pointwise and redefined the top and bottom and updated all of the relevant files in 0 as well.

constant/polyMesh/boundary

Code:

FoamFile
{
    version     2.0;
    format      ascii;
    class       polyBoundaryMesh;
    location    "constant/polyMesh";
    object      boundary;
}

5
(
    frontback
    {
        type empty;
        nFaces 81228;
        startFace 60225;
    }
    inlet
    {
        type patch;
        nFaces 398;
        startFace 141453;
    }
    outlet
    {
        type patch;
        nFaces 398;
        startFace 141851;
    }
    topbottom
    {
        type patch;
        nFaces 398;
        startFace 142249;
    }
    walls
    {
        type wall;
        nFaces 198;
        startFace 142647;
    }
)

simpleFoam log

Code:

Create time

Create mesh for time = 0


SIMPLE: convergence criteria
    field p      tolerance 1e-05
    field U      tolerance 1e-05
    field nuTilda        tolerance 1e-05

Reading field p

Reading field U

Reading/calculating face flux field phi

Selecting incompressible transport model Newtonian
Selecting turbulence model type RAS
Selecting RAS turbulence model SpalartAllmaras
Selecting patchDistMethod meshWave
SpalartAllmarasCoeffs
{
    sigmaNut        0.66666;
    kappa           0.41;
    Cb1             0.1355;
    Cb2             0.622;
    Cw2             0.3;
    Cw3             2;
    Cv1             7.1;
    Cs              0.3;
}

No MRF models present

No finite volume options present


Starting time loop

Time = 0.01

smoothSolver:  Solving for Ux, Initial residual = 1, Final residual = nan, No It                                                                             erations 1000
smoothSolver:  Solving for Uy, Initial residual = 1, Final residual = nan, No It                                                                             erations 1000
DICPCG:  Solving for p, Initial residual = nan, Final residual = nan, No Iterati                                                                             ons 1001
DICPCG:  Solving for p, Initial residual = nan, Final residual = nan, No Iterati                                                                             ons 1001


--> FOAM FATAL IO ERROR:
wrong token type - expected Scalar, found on line 0 the word 'nan'

file: /home/user/OpenFOAM/user-v3.0+/run/tutorials/incompressible/simpleFoam/c                                                                             ylinder/system/data.solverPerformance.p at line 0.

    From function Foam::Istream& Foam::operator>>(Foam::Istream&, Foam::doubleSc                                                                             alar&)
    in file lnInclude/Scalar.C at line 93.

FOAM exiting

edit: Let me try changing to k-epsilon and try that...

ss32 · April 18, 2016, 13:27

Same results for k-epsilon

ss32 · April 19, 2016, 00:15

In case anyone runs into a similar problem, running renumbermesh first did the trick.

akidess · April 19, 2016, 02:58

That can't be right, renumberMesh should not influence the result.

ss32 · April 19, 2016, 10:40

Quote:

Originally Posted by akidess

That can't be right, renumberMesh should not influence the result.

Well it did. I don't know if it was a memory issue at the start or what was happening, but a case that wouldn't run past the first time step runs to completion after using

Code:

renumberMesh -overwrite

I've successfully run a few cases of different turbulence models and meshes that previously failed for the same reason.

April 19, 2016, 02:58		#9
akidess Senior Member Anton Kidess Join Date: May 2009 Location: Germany Posts: 1,377 Rep Power: 30	That can't be right, renumberMesh should not influence the result. __________________ On twitter @akidTwit Spend as much time formulating your questions as you expect people to spend on their answer.

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April 17, 2016, 11:14		#2
ss32 Member Join Date: Apr 2016 Posts: 39 Rep Power: 10	I have changed the top/bottom to patch and assigned them freestream values, still getting the same problem.

April 18, 2016, 06:59		#3
tomf Senior Member Tom Fahner Join Date: Mar 2009 Location: Breda, Netherlands Posts: 647 Rep Power: 32	It looks like you are only solving for Ux, which means you are solving for a 1D problem. Please run checkMesh and make sure you have defined your problem correctly.

April 18, 2016, 13:27		#7
ss32 Member Join Date: Apr 2016 Posts: 39 Rep Power: 10	Same results for k-epsilon

April 19, 2016, 00:15		#8
ss32 Member Join Date: Apr 2016 Posts: 39 Rep Power: 10	In case anyone runs into a similar problem, running renumbermesh first did the trick.