[AndyR]

Folks,
First time using OpenFoam
about 30 yrs using other tools, but feeling like a newb ;-)

Running a small tube bundle problem.
Used the square bend as my starting template and it runs just fine.

The job starts, gets to time = 1 and then just stops.

attached is the dict, and log file.
I can upload the whole thing if necessary.
But first question.

Can I get more verbose output?

Is there a reference pressure in here somewhere? Not sure why the pressure control is showing pMin as low as it is. I have set the back pressure at the outlet to be just above atmospheric. I would expect the inlet pressure to rise to whatever is required to push the flow.

I have clearly made an error in my setup, but can't seem to find it.
Any help is appreciated.
Thanks
Andy

[AndyR]

So I ran
rhoSimpleFoam -dry-run

And... it looks like the solver tries to run

Starting time loop

Time = 1

GAMG: Solving for Uy, Initial residual = 0.40392, Final residual = 0.000781681, No Iterations 1
GAMG: Solving for Uz, Initial residual = 1, Final residual = 0.000715822, No Iterations 1
GAMG: Solving for e, Initial residual = 1, Final residual = 0.00697091, No Iterations 1
GAMG: Solving for p, Initial residual = 1, Final residual = 0.0537728, No Iterations 1
time step continuity errors : sum local = 18767.5, global = 18767.5, cumulative = 18767.5
GAMG: Solving for epsilon, Initial residual = 1, Final residual = 2.09567e-16, No Iterations 1
GAMG: Solving for k, Initial residual = 1, Final residual = 3.25556e-07, No Iterations 1
ExecutionTime = 0.68 s ClockTime = 1 s

End

So....
Is running -dry-run really just running the first time step /iter?
If so , why does it seem to hang when I try and run the whole job?

Hmmm

Any help is appreciated
Thanks
Andy

[AndyR]

So Dry run does not as far as I can tell give me an snapshot of the initial field. That is always an useful debugging tool. Is there a way to do that in OpenFoam?

I did try some different smoother settings and was told residuals were 1e200.
Clearly something wrong. My guess is my initialization of BCs, but I cant find it.

On question.
nCellsInCoarsestLevel was set to some number of order 10 in the example.

For a 625,000 cell model that seems ludicrously small.

Is there any documentation on solver/bc dependencies? solver initial condition dependencies? I have my sym boundaries in all my time 0 files. Not sure that is necessary, or that I specified them correctly.

My mesh has 4 sym planes, 2 define discontinuous boundaries. Do those need to be broken up?

Any help is appreciated
Thanks
Andy

[tas38]

Andy,


More information is needed. Most notably, your boundary condition files and a log file after the simulation has run for a while. I would not overly focus on the specifics of the linear solver settings at this stage.



I assume that since your first post your simulation now runs for a bit as you have stated the residuals are very large, i.e. the solution is diverging.

[AndyR]

Troy,
So it doesn't really run, I fiddled with changed to simpler diagonal solver and got a little output.

Log file is fairly sparse. I know the mistake is mine, but just not getting enough feedback from the code to determine the issue. Can I get a more verbose log file?

It is also not clear what the difference is between
symmetry and symmetryPlane

The Log and BC files are below

Any help is appreciated
Thanks
Andy


Log file:

PHP Code:

/*---------------------------------------------------------------------------*\
| =========                 |                                                 |
| \\      /  F ield         | OpenFOAM: The Open Source CFD Toolbox           |
|  \\    /   O peration     | Version:  v1912                                 |
|   \\  /    A nd           | Website:  [url]www.openfoam.com[/url]                      |
|    \\/     M anipulation  |                                                 |
\*---------------------------------------------------------------------------*/
Build  : _f3950763fe-20191219 OPENFOAM=1912
Arch   : "LSB;label=32;scalar=64"
Exec   : /opt/OpenFOAM/OpenFOAM-v1912/platforms/linux64Gcc63DPInt32Opt/bin/rhoSimpleFoam
Date   : Jan 30 2020
Time   : 09:51:33
Host   : FLWS03
PID    : 28327
I/O    : uncollated
Case   : /home/arobertson/OpenFOAM/arobertson-v1912/run/HXER
nProcs : 1
trapFpe: Floating point exception trapping enabled (FOAM_SIGFPE).
fileModificationChecking : Monitoring run-time modified files using timeStampMaster (fileModificationSkew 10)
allowSystemOperations : Allowing user-supplied system call operations

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

Create mesh for time = 0


SIMPLE: convergence criteria
    field p     tolerance 0.001
    field U     tolerance 0.0001
    field e     tolerance 0.001
    field "(k|epsilon|omega)"     tolerance 0.001

Reading thermophysical properties

Selecting thermodynamics package 
{
    type            hePsiThermo;
    mixture         pureMixture;
    transport       sutherland;
    thermo          hConst;
    equationOfState perfectGas;
    specie          specie;
    energy          sensibleInternalEnergy;
}

Reading field U

Reading/calculating face flux field phi

pressureControl
    pMax 206820
    pMin 10341

Creating turbulence model

Selecting turbulence model type RAS
Selecting RAS turbulence model kEpsilon
RAS
{
    RASModel        kEpsilon;
    turbulence      on;
    printCoeffs     on;
    Cmu             0.09;
    C1              1.44;
    C2              1.92;
    C3              0;
    sigmak          1;
    sigmaEps        1.3;
}

No MRF models present

No finite volume options present

Starting time loop

Time = 1 


Note it just ends. No time 1 folder is created

Clearly I have a major problem with my setup


alphat

PHP Code:

/*--------------------------------*- 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;
    object      alphat;
}
// * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * //

dimensions      [1 -1 -1 0 0 0 0];

internalField   uniform 0;

boundaryField
{
    Inlet
    {
        type            calculated;
        value           $internalField;
    }

    Outlet
    {
        type            calculated;
        value           $internalField;
    }

    TubeWall1
    {
        type            compressible::alphatWallFunction;
        Prt             0.85;
        value           $internalField;
    }
   
    Sym_Xmax
    { 
        type symmetry;
    } 
    Sym_Xmin
    { 
        type symmetry;
    } 
    Sym_Ymax
    { 
        type symmetry;
    } 
    Sym_Ymin
    { 
        type symmetry;
    }
}


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


epsilon

PHP Code:

/*--------------------------------*- 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;
    object      epsilon;
}
// * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * //

dimensions      [0 2 -3 0 0 0 0];

internalField   uniform 0.1;

boundaryField
{
    Inlet
    {
        type            turbulentMixingLengthDissipationRateInlet;
        mixingLength    0.005;
        value           $internalField;
    }

    Outlet
    {
        type            inletOutlet;
        value           $internalField;
        inletValue      $internalField;
    }

    TubeWall1
    {
        type            epsilonWallFunction;
        Cmu             0.09;
        kappa           0.41;
        E               9.8;
        value           $internalField;
    }


    Sym_Xmax
    { 
        type symmetry;
    } 
    Sym_Xmin
    { 
        type symmetry;
    } 
    Sym_Ymax
    { 
        type symmetry;
    } 
    Sym_Ymin
    { 
        type symmetry;
    }
}


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


K

PHP Code:

/*--------------------------------*- 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;
    object      epsilon;
}
// * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * //

dimensions      [0 2 -3 0 0 0 0];

internalField   uniform 0.1;

boundaryField
{
    Inlet
    {
        type            turbulentMixingLengthDissipationRateInlet;
        mixingLength    0.005;
        value           $internalField;
    }

    Outlet
    {
        type            inletOutlet;
        value           $internalField;
        inletValue      $internalField;
    }

    TubeWall1
    {
        type            epsilonWallFunction;
        Cmu             0.09;
        kappa           0.41;
        E               9.8;
        value           $internalField;
    }


    Sym_Xmax
    { 
        type symmetry;
    } 
    Sym_Xmin
    { 
        type symmetry;
    } 
    Sym_Ymax
    { 
        type symmetry;
    } 
    Sym_Ymin
    { 
        type symmetry;
    }
}


// ************************************************************************* '// 


nut

PHP Code:

/*--------------------------------*- 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;
    object      nut;
}
// * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * //

dimensions      [0 2 -1 0 0 0 0];

internalField   uniform 0.01;

boundaryField
{
    Inlet
    {
        type            calculated;
        value           $internalField;
    }

    Outlet
    {
        type            calculated;
        value           $internalField;
    }

    TubeWall1
    {
        type            nutkWallFunction;
        Cmu             0.09;
        kappa           0.41;
        E               9.8;
        value           $internalField;
    }
    Sym_Xmax
    { 
        type symmetry;
    } 

    Sym_Xmin
    { 
        type symmetry;
    } 

    Sym_Ymax
    { 
        type symmetry;
    } 

    Sym_Ymin
    { 
        type symmetry;
    }
} 


P

PHP Code:

/*--------------------------------*- 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;
    object      p;
}
// * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * //

dimensions      [1 -1 -2 0 0 0 0];

internalField   uniform 103410;

boundaryField
{
    Inlet
    {
        type            zeroGradient;
    }

    Outlet
    {
        type            fixedValue;
        value           uniform 103410;

    }

    TubeWall1
    {
        type            zeroGradient;
    }
    
    Sym_Xmax
    { 
        type symmetry;
    }
 
    Sym_Xmin
    { 
        type symmetry;
    } 

    Sym_Ymax
    { 
        type symmetry;
    } 

    Sym_Ymin
    { 
        type symmetry;
    }
}


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


T

PHP Code:

/*--------------------------------*- 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;
    object      T;
}
// * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * //

dimensions      [0 0 0 1 0 0 0];

internalField   uniform 1000;

boundaryField
{
    Inlet
    {
        type            fixedValue;
        value           uniform 1000;
    }

    Outlet
    {
        type            inletOutlet;
        value           $internalField;
        inletValue      $internalField;
    }

    TubeWall1
    {
        type            fixedValue;
        value           uniform 1100;
    }

    Sym_Xmax
    { 
        type symmetry;
    } 

    Sym_Xmin
    { 
        type symmetry;
    } 

    Sym_Ymax
    { 
        type symmetry;
    } 

    Sym_Ymin
    { 
        type symmetry;
    }
}

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


U

PHP Code:

/*--------------------------------*- 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       volVectorField;
    object      U;
}
// * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * //

dimensions      [0 1 -1 0 0 0 0];

internalField   uniform (0 0 0.01);

boundaryField
{
    Inlet
    {
         type      fixedValue;
         value   uniform   (0.0 0.0 0.25);
    }

    Outlet
    {
        type            inletOutlet;
        value           $internalField;
        inletValue      $internalField;
    }

    TubeWall1
    {
        type            noSlip;
    }

    Sym_Xmax
    { 
        type symmetry;
    } 

    Sym_Xmin
    { 
        type symmetry;
    } 

    Sym_Ymax
    { 
        type symmetry;
    } 

    Sym_Ymin
    { 
        type symmetry;
    }
}
// ************************************************************************* // 


[me45]

I have similar trouble.

[sapujapu]

Right now you're setting an inlet velocity as BC. However, I don't see any info on your inlet density. rhoSimpleFoam is a compressible solver so I think you need that.


When you use a compressible solver, there's two ways of combining BCs for the inlet and outlet.

First option: Set a total pressure at the inlet and a static pressure at the outlet. This can be quite unstable if you have a complicated flowfield.

Second option: Set a massflow at the inlet and a static pressure at the outlet. The massflow BC works as like this:

inlet
{
type flowRateInletVelocity;
massFlowRate constant $yourvalue;
rhoInlet 0.5; // This is just an optional first guess and can be left out completely.
}
This method is quite stable, I've used it successfully to simulate very similar cases to yours.

If you really want to use a total pressure/static pressure setup, you can use the massflow to initialize the solution and then later change it to total pressure. I've found this to be quite stable.