[Sugajen]

Hi all,

I am new to OpenFOAM. I started modeling a rectangular domain with inlet velocity and outlet pressure. Tried to solve it with icoFoam but unfortunately from the very first time step, the pressure in the internalField is equal to the outlet pressure. No matter how small the outlet pressure is, internalField takes that value. Any help/suggestions will be very much appreciated.

Pressure BC

FoamFile
{
    version     2.0;
    format      ascii;
    class       volScalarField;
    object      p;
}
// * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * //

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

internalField   uniform 0;

boundaryField
{

    inlet
    {
        type            zeroGradient;
    }

    outlet
    {
        type            fixedValue;
        value           uniform 6010;
    }

    fixedWalls
    {
        type            zeroGradient;
    }

    lowerMembrane
    {
        type            zeroGradient;
    }

    upperMembrane
    {
        type            zeroGradient;
    }

}

Velocity BC

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

internalField   uniform (0 0 0);

boundaryField
{

    inlet
    {
        type            fixedValue;
        value           uniform (0.1 0 0);
    }

    outlet
    {
        type            zeroGradient;
    }

    fixedWalls
    {
        type            noSlip;
    }
    lowerMembrane
    {
        type            noSlip;
    }
    upperMembrane
    {
        type            noSlip;
    }

}

blockMeshDict

convertToMeters 0.001;

vertices
(
    (0 0 0)   
    (4.5 0 0)
    (4.5 4.5 0)
    (0 4.5 0)
    (0 0 1)
    (4.5 0 1)
    (4.5 4.5 1)
    (0 4.5 1)
);

blocks
(
    hex (0 1 2 3 4 5 6 7) (9 9 2) simpleGrading (1 1 1)
);

edges
(
);

boundary
(
    inlet
    {
        type patch;
        faces
        (
         (0 4 7 3)   
        );
    }

    outlet
    {
        type patch;
        faces
        (
         (1 2 6 5)   
        );
    }

    fixedWalls
    {
        type wall;
        faces
        (   (3 7 6 2)
            (1 5 4 0)
            
        );
    }
	
    upperMembrane
    {
	type wall;
	faces
	(
	 (4 5 6 7)
	);
    }

    lowerMembrane
    {
	type wall;
	faces
	(
         (0 3 2 1)
	);
    }

);

mergePatchPairs
(
);

[bao42]

How did you find "the pressure in the internalField is equal to the outlet pressure"? By viewing the results in some post-processor like paraview? If that's the case, you could probably try cell data instead of point data.

[Joshua14]

You have initial fields set to 0 for pressure, with a high outlet pressure of 6010. Your pressure outlet is therefore going to dominate the domain. I would suggest initializing your pressure field as 6010 (same as your outlet). That way velocity can then effect the initialized system.

Joshua

[Sugajen]

@Bao & @Joshua,
I tried both your suggestions but didn't work. Do you think I should consider changing my boundary conditions - zeroGradient to something else? When I changed them to 0, it did not work.

[Joshua14]

Have you tried running another transient solver like pisoFoam or pimpleFoam? In my opinion they are much better solvers then icoFoam.

Joshua

[Sugajen]

@Joshua
Actually, I was using pimpleFoam at first. But it throws an error at the eight time step which I am posting below. That's why I switched to icoFoam.

 Courant Number mean: 1.95828e+100 max: 1.87544e+101
Time = 0.088

PIMPLE: iteration 1
GAMG:  Solving for p, Initial residual = 0.832383, Final residual = 0.0176052, No Iterations 1
time step continuity errors : sum local = 1.25645e+99, global = -9.31495e+98, cumulative = -1.0294e+99
smoothSolver:  Solving for sigmaxx, Initial residual = 0.747741, Final residual = 0.0639805, No Iterations 2
smoothSolver:  Solving for sigmaxy, Initial residual = 0.693769, Final residual = 0.055105, No Iterations 2
smoothSolver:  Solving for sigmaxz, Initial residual = 0.682691, Final residual = 0.054775, No Iterations 2
smoothSolver:  Solving for sigmayy, Initial residual = 0.56351, Final residual = 0.0472953, No Iterations 2
smoothSolver:  Solving for sigmayz, Initial residual = 0.543234, Final residual = 0.0470379, No Iterations 2
smoothSolver:  Solving for sigmazz, Initial residual = 0.528148, Final residual = 0.0493034, No Iterations 2
PIMPLE: iteration 2
GAMG:  Solving for p, Initial residual = 0.710975, Final residual = 0.0105144, No Iterations 1
time step continuity errors : sum local = 2.26049e+99, global = -5.74118e+98, cumulative = -1.60351e+99
#0  Foam::error::printStack(Foam::Ostream&) at ??:?
#1  Foam::sigFpe::sigHandler(int) at ??:?
#2  ? in "/lib/x86_64-linux-gnu/libc.so.6"
#3  void Foam::dot<Foam::SymmTensor<double>, Foam::Tensor<double> >(Foam::Field<Foam::innerProduct<Foam::SymmTensor<double>, Foam::Tensor<double> >::type>&, Foam::UList<Foam::SymmTensor<double> > const&, Foam::UList<Foam::Tensor<double> > const&) at ??:?
#4  Foam::tmp<Foam::GeometricField<Foam::innerProduct<Foam::SymmTensor<double>, Foam::Tensor<double> >::type, Foam::fvPatchField, Foam::volMesh> > Foam::operator&<Foam::SymmTensor<double>, Foam::Tensor<double>, Foam::fvPatchField, Foam::volMesh>(Foam::GeometricField<Foam::SymmTensor<double>, Foam::fvPatchField, Foam::volMesh> const&, Foam::GeometricField<Foam::Tensor<double>, Foam::fvPatchField, Foam::volMesh> const&) at ??:?
#5  Foam::laminarModels::Maxwell<Foam::IncompressibleTurbulenceModel<Foam::transportModel> >::correct() at ??:?
#6  ? in "/home/sugajen/OpenFOAM/OpenFOAM-v1612+/platforms/linux64GccDPInt32Opt/bin/pimpleFoam"
#7  __libc_start_main in "/lib/x86_64-linux-gnu/libc.so.6"
#8  ? in "/home/sugajen/OpenFOAM/OpenFOAM-v1612+/platforms/linux64GccDPInt32Opt/bin/pimpleFoam"
Floating point exception (core dumped)

The Courant number shoots up. What do you think is the problem ?

Thanks!

[Joshua14]

Your time step is too large.
1) Reduce your time step by a magnitude of 10
2) You can turn on adjustable timestep for pimple and set a max Co of 1.

Joshua

[Sugajen]

Thank you Joshua!

Did as you suggested. Reduced the timeStep size as well as set a maxCo. But it is still crashing. Though we set a maxCo of 0.5, the iterations go well beyond that. Am I missing something?

Please find my controlDict file and output of the last successful iteration below.

controlDict:

 FoamFile
{
    version     2.0;
    format      ascii;
    class       dictionary;
    location    "system";
    object      controlDict;
}
// * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * //

application     pimpleFoam;

startFrom       startTime;

startTime       0;

stopAt          endTime;

endTime         0.1;

deltaT          0.0001;

writeControl    timeStep;

writeInterval   100;

purgeWrite      0;

writeFormat     ascii;

writePrecision  6;

writeCompression off;

timeFormat      general;

timePrecision   6;

runTimeModifiable true;

adjustTimeStep true;

maxDeltaT	0.0001;

maxCo		0.5;

Output:

 Courant Number mean: 0.663709 max: 6.71235
deltaT = 2.38759e-104
Time = 0.0714291

PIMPLE: iteration 1
GAMG:  Solving for p, Initial residual = 0.729669, Final residual = 0.00895447, No Iterations 1
time step continuity errors : sum local = 0.000363231, global = 2.0545e-05, cumulative = 23.0525
smoothSolver:  Solving for sigmaxx, Initial residual = 0.156834, Final residual = 0.000662181, No Iterations 1
smoothSolver:  Solving for sigmaxy, Initial residual = 0.13604, Final residual = 0.000885931, No Iterations 1
smoothSolver:  Solving for sigmaxz, Initial residual = 0.140816, Final residual = 0.000860439, No Iterations 1
smoothSolver:  Solving for sigmayy, Initial residual = 0.126032, Final residual = 0.00120917, No Iterations 1
smoothSolver:  Solving for sigmayz, Initial residual = 0.126016, Final residual = 0.0011654, No Iterations 1
smoothSolver:  Solving for sigmazz, Initial residual = 0.128925, Final residual = 0.00115707, No Iterations 1
PIMPLE: iteration 2
GAMG:  Solving for p, Initial residual = 0.143409, Final residual = 0.00322247, No Iterations 1
time step continuity errors : sum local = 0.000251366, global = 4.45186e-05, cumulative = 23.0525
smoothSolver:  Solving for sigmaxx, Initial residual = 0.134324, Final residual = 0.000689652, No Iterations 1
smoothSolver:  Solving for sigmaxy, Initial residual = 0.119069, Final residual = 0.00070716, No Iterations 1
smoothSolver:  Solving for sigmaxz, Initial residual = 0.121229, Final residual = 0.000755986, No Iterations 1
smoothSolver:  Solving for sigmayy, Initial residual = 0.094852, Final residual = 0.000903834, No Iterations 1
smoothSolver:  Solving for sigmayz, Initial residual = 0.0985399, Final residual = 0.000890833, No Iterations 1
smoothSolver:  Solving for sigmazz, Initial residual = 0.103933, Final residual = 0.000922095, No Iterations 1
PIMPLE: iteration 3
GAMG:  Solving for p, Initial residual = 0.13444, Final residual = 0.00277385, No Iterations 1
time step continuity errors : sum local = 0.000274193, global = 4.10307e-05, cumulative = 23.0526
smoothSolver:  Solving for sigmaxx, Initial residual = 0.1354, Final residual = 0.00123334, No Iterations 1
smoothSolver:  Solving for sigmaxy, Initial residual = 0.130423, Final residual = 0.00140532, No Iterations 1
smoothSolver:  Solving for sigmaxz, Initial residual = 0.133621, Final residual = 0.00144555, No Iterations 1
smoothSolver:  Solving for sigmayy, Initial residual = 0.107672, Final residual = 0.00154916, No Iterations 1
smoothSolver:  Solving for sigmayz, Initial residual = 0.112155, Final residual = 0.00160124, No Iterations 1
smoothSolver:  Solving for sigmazz, Initial residual = 0.116955, Final residual = 0.0016714, No Iterations 1
PIMPLE: iteration 4
GAMG:  Solving for p, Initial residual = 0.154451, Final residual = 0.00313977, No Iterations 1
time step continuity errors : sum local = 0.000397578, global = 3.54349e-05, cumulative = 23.0526
smoothSolver:  Solving for sigmaxx, Initial residual = 0.157579, Final residual = 0.00266918, No Iterations 1
smoothSolver:  Solving for sigmaxy, Initial residual = 0.152596, Final residual = 0.00308912, No Iterations 1
smoothSolver:  Solving for sigmaxz, Initial residual = 0.156793, Final residual = 0.00311075, No Iterations 1
smoothSolver:  Solving for sigmayy, Initial residual = 0.146138, Final residual = 0.00377687, No Iterations 1
smoothSolver:  Solving for sigmayz, Initial residual = 0.15078, Final residual = 0.00380433, No Iterations 1
smoothSolver:  Solving for sigmazz, Initial residual = 0.154905, Final residual = 0.0038161, No Iterations 1
PIMPLE: iteration 5
GAMG:  Solving for p, Initial residual = 0.196638, Final residual = 0.00411544, No Iterations 1
time step continuity errors : sum local = 0.000704938, global = 3.31079e-05, cumulative = 23.0526
smoothSolver:  Solving for sigmaxx, Initial residual = 0.205283, Final residual = 0.00651574, No Iterations 1
smoothSolver:  Solving for sigmaxy, Initial residual = 0.197487, Final residual = 0.00771348, No Iterations 1
smoothSolver:  Solving for sigmaxz, Initial residual = 0.202468, Final residual = 0.00770267, No Iterations 1
smoothSolver:  Solving for sigmayy, Initial residual = 0.196547, Final residual = 0.00977995, No Iterations 1
smoothSolver:  Solving for sigmayz, Initial residual = 0.198549, Final residual = 0.00964261, No Iterations 1
smoothSolver:  Solving for sigmazz, Initial residual = 0.205165, Final residual = 0.00963499, No Iterations 1
PIMPLE: iteration 6
GAMG:  Solving for p, Initial residual = 0.267345, Final residual = 0.00569992, No Iterations 1
time step continuity errors : sum local = 0.00145128, global = 3.15007e-05, cumulative = 23.0527
smoothSolver:  Solving for sigmaxx, Initial residual = 0.277455, Final residual = 0.0152066, No Iterations 1
smoothSolver:  Solving for sigmaxy, Initial residual = 0.265611, Final residual = 0.0184275, No Iterations 1
smoothSolver:  Solving for sigmaxz, Initial residual = 0.270851, Final residual = 0.0180328, No Iterations 1
smoothSolver:  Solving for sigmayy, Initial residual = 0.271589, Final residual = 0.0241334, No Iterations 1
smoothSolver:  Solving for sigmayz, Initial residual = 0.269955, Final residual = 0.0229864, No Iterations 1
smoothSolver:  Solving for sigmazz, Initial residual = 0.276123, Final residual = 0.0222251, No Iterations 1
PIMPLE: iteration 7
GAMG:  Solving for p, Initial residual = 0.354711, Final residual = 0.00776282, No Iterations 1
time step continuity errors : sum local = 0.00330826, global = 1.97892e-05, cumulative = 23.0527
smoothSolver:  Solving for sigmaxx, Initial residual = 0.356287, Final residual = 0.0325556, No Iterations 1
smoothSolver:  Solving for sigmaxy, Initial residual = 0.341959, Final residual = 0.00701936, No Iterations 2
smoothSolver:  Solving for sigmaxz, Initial residual = 0.346168, Final residual = 0.00671219, No Iterations 2
smoothSolver:  Solving for sigmayy, Initial residual = 0.356212, Final residual = 0.00887653, No Iterations 2
smoothSolver:  Solving for sigmayz, Initial residual = 0.352708, Final residual = 0.00833179, No Iterations 2
smoothSolver:  Solving for sigmazz, Initial residual = 0.356016, Final residual = 0.00778691, No Iterations 2
PIMPLE: iteration 8
GAMG:  Solving for p, Initial residual = 0.435929, Final residual = 0.00935036, No Iterations 1
time step continuity errors : sum local = 0.00741005, global = 0.000179898, cumulative = 23.0529
smoothSolver:  Solving for sigmaxx, Initial residual = 0.42109, Final residual = 0.0130746, No Iterations 2
smoothSolver:  Solving for sigmaxy, Initial residual = 0.432944, Final residual = 0.0158246, No Iterations 2
smoothSolver:  Solving for sigmaxz, Initial residual = 0.436075, Final residual = 0.0151397, No Iterations 2
smoothSolver:  Solving for sigmayy, Initial residual = 0.445616, Final residual = 0.0183585, No Iterations 2
smoothSolver:  Solving for sigmayz, Initial residual = 0.439054, Final residual = 0.0176198, No Iterations 2
smoothSolver:  Solving for sigmazz, Initial residual = 0.433173, Final residual = 0.016696, No Iterations 2
PIMPLE: iteration 9
GAMG:  Solving for p, Initial residual = 0.50547, Final residual = 0.010613, No Iterations 1
time step continuity errors : sum local = 0.0168803, global = 0.00190167, cumulative = 23.0548
#0  Foam::error::printStack(Foam::Ostream&) at ??:?
#1  Foam::sigFpe::sigHandler(int) at ??:?
#2  ? in "/lib/x86_64-linux-gnu/libc.so.6"
#3  Foam::twoSymm(Foam::Field<Foam::SymmTensor<double> >&, Foam::UList<Foam::Tensor<double> > const&) at ??:?
#4  Foam::tmp<Foam::GeometricField<Foam::SymmTensor<double>, Foam::fvPatchField, Foam::volMesh> > Foam::twoSymm<Foam::fvPatchField, Foam::volMesh>(Foam::tmp<Foam::GeometricField<Foam::Tensor<double>, Foam::fvPatchField, Foam::volMesh> > const&) at ??:?
#5  Foam::laminarModels::Maxwell<Foam::IncompressibleTurbulenceModel<Foam::transportModel> >::correct() at ??:?
#6  ? in "/home/sugajen/OpenFOAM/OpenFOAM-v1612+/platforms/linux64GccDPInt32Opt/bin/pimpleFoam"
#7  __libc_start_main in "/lib/x86_64-linux-gnu/libc.so.6"
#8  ? in "/home/sugajen/OpenFOAM/OpenFOAM-v1612+/platforms/linux64GccDPInt32Opt/bin/pimpleFoam"
Floating point exception (core dumped)

[Joshua14]

What scheme are you using for time? Euler?

Joshua

[Sugajen]

I have been using backward!

[Joshua14]

Try using Euler as see how that does.

Joshua

[Sugajen]

Sure Joshua! Just tried CrankNicolson 0.9, Euler, localEuler, none and steadyState.
All of them fail at time = 0.07.
There is something happening at t = 0.07.

[Joshua14]

At this point I would be guessing its your mesh. Maybe something isn't refined enough or you have a funky cell.

Joshua

[Sugajen]

That was a good guess! As I doubled and quadrupled the cells per side of the mesh, the solution crashed at half and quarter of the previous total times correspondingly.

I checked the mesh and vertices multiple times but nothing I can see wrong. Any thoughts?

Thank you!