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Old   November 21, 2011, 11:54
Default SimpleFoam solver running error
  #1
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Anirudh
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Dear all,
Could anybody help me out with this error.I am totally new with OpenFoam

dimensions [0 1 -1 0 0 0 0];
internalField uniform (1 0 0);
boundaryField

{
inlet

{

type fixedValue;

value uniform (1 0 0);

}

top

{

type fixedValue;

value uniform (0 0 0);

}

outlet

{

type zeroGradient;

}

bottomAndSide

{

type fixedValue;

value uniform (0 0 0);

}



frontAndBack

{

type (0 0 0);

}



}
I get the following error after running my solver simpleFoam....

FOAM FATAL IO ERROR:
wrong token type - expected word, found on line 47 the punctuation token '('

file: /home/anirudh/Desktop/Ani/0/U::boundaryField::frontAndBack::type at line 47.

From function operator>>(Istream&, word&)
in file primitives/strings/word/wordIO.C at line 74.

FOAM exitingany Idea of this error dude
?

Than you ..
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Old   November 21, 2011, 12:14
Default Need To Fix Boundary Definition
  #2
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Michael Ahlmann
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You have the frontAndBack boundary condition listed as "type (0 0 0)". I assume you are doing a 2D geometry, as such, you should be using type "empty;". This tells OpenFOAM that your geometry is in fact 2D. I reccomend looking in at the cavity case from the OpenFOAM tutorial in detail. Best of luck!
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Old   November 21, 2011, 12:29
Default
  #3
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Anirudh
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Dear Mr.Micheal,
Thank you for your reply, I am doing for 3_D case
This is the latest error

anirudh@anirudh:~/Desktop/Ani$ simpleFoam
/*---------------------------------------------------------------------------*\
| ========= | |
| \\ / F ield | OpenFOAM: The Open Source CFD Toolbox |
| \\ / O peration | Version: 2.0.1 |
| \\ / A nd | Web: www.OpenFOAM.com |
| \\/ M anipulation | |
\*---------------------------------------------------------------------------*/
Build : 2.0.1-51f1de99a4bc
Exec : simpleFoam
Date : Nov 21 2011
Time : 17:22:23
Host : anirudh
PID : 3836
Case : /home/anirudh/Desktop/Ani
nProcs : 1
sigFpe : Enabling floating point exception trapping (FOAM_SIGFPE).
fileModificationChecking : Monitoring run-time modified files using timeStampMaster
allowSystemOperations : Disallowing user-supplied system call operations

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

Create mesh for time = 0

Reading field p

Reading field U

Reading/calculating face flux field phi

Selecting incompressible transport model Newtonian
Selecting RAS turbulence model kEpsilon


--> FOAM FATAL IO ERROR:
cannot find file

file: /home/anirudh/Desktop/Ani/0/k at line 0.

From function regIOobject::readStream()
in file db/regIOobject/regIOobjectRead.C at line 73.

FOAM exiting

anirudh@anirudh:~/Desktop/Ani$
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Old   November 21, 2011, 13:15
Default
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Michael Ahlmann
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OpenFOAM tends to be pretty good about telling you what's going on. In this case, it's complaining the file k doesn't exist. I presume you are running a turbulent case? You need to add k and epsilon (or omega or... depending on your chosen turbulence model) to your zero directory. You can find examples in the tutorials. Obviously the setup is case dependent, but typically you would want to define k and epsilon as fixed value at the inlet (look in the cavity tutorial for how to calculate them), zero gradient at the exit, and wall functions on all the walls. If your case is not turbulent, you can adjust constant/RASProperties and set the transport model to "laminar" instead.
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Old   November 22, 2011, 10:33
Default Open Foam Help with time steps
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Anirudh
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Thank you for your reply Mr.Michael
I have given endTime in controldict as 500 and time steps = 0.05
But when I ran the solver simpleFoam. Its converging @ 17.55 ...Is it desirable ? or what should I change in my fvsolution.
this is my present fvsolution :
FoamFile
{
version 2.0;
format ascii;
class dictionary;
location "system";
object fvSolution;
}
// * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * //

solvers
{
p
{
solver PCG;
preconditioner DIC;
tolerance 1e-07;
relTol 0.001;
}

U
{
solver PBiCG;
preconditioner DILU;
tolerance 1e-07;
relTol 0.001;
}

k
{
solver PBiCG;
preconditioner DILU;
tolerance 1e-07;
relTol 0.001;
}

epsilon
{
solver PBiCG;
preconditioner DILU;
tolerance 1e-07;
relTol 0.001;
}

R
{
solver PBiCG;
preconditioner DILU;
tolerance 1e-05;
relTol 0.1;
}

nuTilda
{
solver PBiCG;
preconditioner DILU;
tolerance 1e-05;
relTol 0.1;
}
}

SIMPLE
{
nNonOrthogonalCorrectors 0;

residualControl
{
p 1e-2;
U 1e-3;
"(k|epsilon|omega)" 1e-3;
}
}

relaxationFactors
{
p 0.3;
U 0.7;
k 0.7;
epsilon 0.7;
R 0.7;
nuTilda 0.7;
}


// ************************************************** *********************** //
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Old   November 22, 2011, 12:25
Default
  #6
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Michael Ahlmann
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First of all, simpleFoam is a steady state solver. As such, the time step is a meaningless parameter except for the fact that it changes the name of the output directories. It has no impact on the numerics. Therefore, most people tend to set time step to 1, so that the timestep acts as an iteration counter, but that's up to you.

As for your convergence questions: the residualControl section governs the convergence critereon of the solver. If your desire is for the solver to run for 100 iterations, you can just comment out the residual control section in your fvSolution file. The solver will give you a message as it begins to run stating that no convergence critereon was found, so it's going to run for whatever number of iterations you specified in controlDict.

By extension, if you want to specify a convergence critereon that is tighter than your current choice, you can obviously just lower the values in the residualControl section of fvSolution. I tend to use 1e-05 myself, but as I'm sure you know, you can't always rely on residuals alone to ensure convergence.
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