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Old   March 28, 2012, 00:15
Unhappy no convergence with simplefoam
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张德胜
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Everyone,i use simplefoam with standard k-epsilon model to calculate the wind farm.when i type the command "simpleFoam",i get the following information:Create mesh for time = 0

Reading field p

Reading field U

--> FOAM Warning :
From function Field<Type>::Field(const word& keyword, const dictionary&, const label)
in file /opt/openfoam210/src/OpenFOAM/lnInclude/Field.C at line 262
Reading "/root/OpenFOAM/root-2.1.0/run/tutorials/incompressible/simpleFoam/wf39/0/U::boundaryField::inlet" from line 37 to line 16
expected keyword 'uniform' or 'nonuniform', assuming deprecated Field format from Foam version 2.0.
Reading/calculating face flux field phi

Selecting incompressible transport model Newtonian
Selecting RAS turbulence model kEpsilon
kEpsilonCoeffs
{
Cmu 0.028;
C1 1.5;
C2 1.92;
C3 -0.33;
sigmak 1;
sigmaEps 2.51;
Prt 1;
}

No field sources present


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


Starting time loop

Time = 1

smoothSolver: Solving for Ux, Initial residual = 1, Final residual = 0.00644545010997, No Iterations 3
smoothSolver: Solving for Uy, Initial residual = 1, Final residual = 0.00464444535134, No Iterations 4
smoothSolver: Solving for Uz, Initial residual = 1, Final residual = 0.00708579374941, No Iterations 5
GAMG: Solving for p, Initial residual = 1, Final residual = 0.00735995074387, No Iterations 5
GAMG: Solving for p, Initial residual = 0.000167838426709, Final residual = 1.56259657312e-06, No Iterations 6
GAMG: Solving for p, Initial residual = 2.2891470536e-05, Final residual = 1.89675102907e-07, No Iterations 4
GAMG: Solving for p, Initial residual = 4.86359414644e-06, Final residual = 4.25624108873e-08, No Iterations 4
time step continuity errors : sum local = 3.77016513754e-08, global = -7.42217873687e-09, cumulative = -7.42217873687e-09
smoothSolver: Solving for epsilon, Initial residual = 1, Final residual = 0.00132760727343, No Iterations 2
smoothSolver: Solving for k, Initial residual = 1, Final residual = 0.00285899835651, No Iterations 2
bounding k, min: 0 max: 50.8029155486 average: 1.44150802022
ExecutionTime = 126.62 s ClockTime = 141 s

Time = 2

smoothSolver: Solving for Ux, Initial residual = 0.446656785658, Final residual = 0.00197538615297, No Iterations 2
smoothSolver: Solving for Uy, Initial residual = 0.143272919974, Final residual = 0.000770220501008, No Iterations 3
smoothSolver: Solving for Uz, Initial residual = 0.159528815298, Final residual = 0.00142906124564, No Iterations 2
GAMG: Solving for p, Initial residual = 0.374485256388, Final residual = 0.00336921418749, No Iterations 6
GAMG: Solving for p, Initial residual = 0.00020659453246, Final residual = 1.28186320376e-06, No Iterations 7
GAMG: Solving for p, Initial residual = 5.21634568919e-05, Final residual = 4.89086468001e-07, No Iterations 4
GAMG: Solving for p, Initial residual = 1.85185182451e-05, Final residual = 7.29808804296e-08, No Iterations 5
time step continuity errors : sum local = 5.23267147276e-08, global = -9.14582863274e-09, cumulative = -1.65680073696e-08
#0 Foam::error:rintStack(Foam::Ostream&) in "/opt/openfoam210/platforms/linuxGccDPOpt/lib/libOpenFOAM.so"
#1 Foam::sigFpe::sigHandler(int) in "/opt/openfoam210/platforms/linuxGccDPOpt/lib/libOpenFOAM.so"
#2 Uninterpreted:
#3 Foam::divide(Foam::Field<double>&, Foam::UList<double> const&, Foam::UList<double> const&) in "/opt/openfoam210/platforms/linuxGccDPOpt/lib/libOpenFOAM.so"
#4 void Foam::divide<Foam::fvPatchField, Foam::volMesh>(Foam::GeometricField<double, Foam::fvPatchField, Foam::volMesh>&, Foam::GeometricField<double, Foam::fvPatchField, Foam::volMesh> const&, Foam::GeometricField<double, Foam::fvPatchField, Foam::volMesh> const&) in "/opt/openfoam210/platforms/linuxGccDPOpt/lib/libincompressibleRASModels.so"
#5 Foam::tmp<Foam::GeometricField<double, Foam::fvPatchField, Foam::volMesh> > Foam:perator/<Foam::fvPatchField, Foam::volMesh>(Foam::tmp<Foam::GeometricField<doub le, Foam::fvPatchField, Foam::volMesh> > const&, Foam::GeometricField<double, Foam::fvPatchField, Foam::volMesh> const&) in "/opt/openfoam210/platforms/linuxGccDPOpt/lib/libincompressibleRASModels.so"
#6 Foam::incompressible::RASModels::kEpsilon::correct () in "/opt/openfoam210/platforms/linuxGccDPOpt/lib/libincompressibleRASModels.so"
#7
at /opt/openfoam210/applications/solvers/incompressible/simpleFoam/simpleFoam.C:66
#8 __libc_start_main in "/lib/tls/i686/cmov/libc.so.6"
#9
in "/opt/openfoam210/platforms/linuxGccDPOpt/bin/simpleFoam"
浮点数例外
who can give me some advice?Thanks every reply.
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Old   March 28, 2012, 00:40
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my fvsolution is:
/*--------------------------------*- C++ -*----------------------------------*\
| ========= | |
| \\ / F ield | OpenFOAM: The Open Source CFD Toolbox |
| \\ / O peration | Version: 2.1.0 |
| \\ / A nd | Web: www.OpenFOAM.org |
| \\/ M anipulation | |
\*---------------------------------------------------------------------------*/
FoamFile
{
version 2.0;
format ascii;
class dictionary;
object fvSolution;
}
// * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * //

solvers
{
p
{
solver GAMG;
tolerance 1e-7;
relTol 0.01;
smoother GaussSeidel;
nPreSweeps 0;
nPostSweeps 2;
cacheAgglomeration on;
agglomerator faceAreaPair;
nCellsInCoarsestLevel 10;
mergeLevels 1;
}

U
{
solver smoothSolver;
smoother GaussSeidel;
tolerance 1e-8;
relTol 0.1;
nSweeps 1;
}

k
{
solver smoothSolver;
smoother GaussSeidel;
tolerance 1e-8;
relTol 0.1;
nSweeps 1;
}

epsilon
{
solver smoothSolver;
smoother GaussSeidel;
tolerance 1e-8;
relTol 0.1;
nSweeps 1;
}
}

SIMPLE
{
nNonOrthogonalCorrectors 3;

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

relaxationFactors
{
fields
{
p 0.2;
}
equations
{
U 0.7;
k 0.7;
epsilon 0.7;
}
}

cache
{
grad(U);
}

// ************************************************** *********************** //
my fvschemes is:
/*--------------------------------*- C++ -*----------------------------------*\
| ========= | |
| \\ / F ield | OpenFOAM: The Open Source CFD Toolbox |
| \\ / O peration | Version: 2.1.0 |
| \\ / A nd | Web: www.OpenFOAM.org |
| \\/ M anipulation | |
\*---------------------------------------------------------------------------*/
FoamFile
{
version 2.0;
format ascii;
class dictionary;
object fvSchemes;
}
// * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * //

ddtSchemes
{
default steadyState;
}

gradSchemes
{
default Gauss linear;
grad(p) Gauss linear;
grad(U) Gauss linear;
}

divSchemes
{
default none;
div(phi,U) Gauss upwind grad(U);
div((nuEff*dev(T(grad(U))))) Gauss linear;
div(phi,epsilon) Gauss upwind;
div(phi,k) Gauss upwind;
}

laplacianSchemes
{
default Gauss linear limited 0.333;
}

interpolationSchemes
{
default linear;
}

snGradSchemes
{
default limited 0.333;
}

fluxRequired
{
default no;
p;
}


// ************************************************** *********************** //
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Old   March 28, 2012, 05:22
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Don't know if it may cause the issue, but, as the error says, you're missing the word "uniform" in your U conditions.
I would start by correcting that.
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Old   March 28, 2012, 05:48
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Thanks for your reply.I think it is just a warning and it should not the reason for my problem.Because i can calculate well in the other case with the warning.
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Old   March 28, 2012, 06:44
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Hi,
if you are sure that your BCs are okay for U (you can check in paraview) I would try to stabilize the first iterations by using a cellLimited grad schemes and setting the relaxation factors for k and eps to 05. or 0.4

Best regards

Stawrogin
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Old   March 28, 2012, 07:03
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Thanks for your reply.I will ues your advice some seconds later.I hope it will works.Thanks again.
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Old   March 28, 2012, 07:05
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which solver for p,u,k,epsilon should i choose?
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Old   March 28, 2012, 07:19
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when i use cellLimited,there gives me the following error:--> FOAM FATAL IO ERROR:
Grad scheme not specified

Valid grad schemes are :

8
(
Gauss
cellLimited
cellMDLimited
extendedLeastSquares
faceLimited
faceMDLimited
fourth
leastSquares
)


file: /root/OpenFOAM/root-2.1.0/run/tutorials/incompressible/simpleFoam/wf40/system/fvSchemes::gradSchemes::grad(U) at line 26.

From function gradScheme<Type>::New(const fvMesh& mesh, Istream& schemeData)
in file /home/opencfd/OpenFOAM/OpenFOAM-2.1.0/src/finiteVolume/lnInclude/gradScheme.C at line 54.

FOAM exiting
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Old   March 28, 2012, 09:01
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Hi
I would try:

gradSchemes
{
default cellLimited Gauss linear 1;
}

Stawrogin
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Old   March 28, 2012, 10:01
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Thanks for your advice.I tryed following your advice,but it failed.can you give me more advice about others?
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Old   March 28, 2012, 11:06
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Hi,

When you used cellLimited Gauss linear 1; what do you mean it failed. Did it fail to even start or did it fail to converge like before?

And also, is there a reason for using limited scheme for sngrad and laplacian terms?

Kalyan
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Old   March 28, 2012, 20:19
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it fail to converge like before.i make some changes,and it convergence.But i do not know the output is right or not.when i solve my problem,i will share my experience.
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Old   March 29, 2012, 21:42
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The following is my case files:https://dl-web.dropbox.com/u/69253136/system/fvSchemes
https://dl-web.dropbox.com/u/69253136/system/fvSolution
https://dl-web.dropbox.com/u/69253136/0/epsilon
https://dl-web.dropbox.com/u/69253136/0/k
https://dl-web.dropbox.com/u/69253136/0/nut
https://dl-web.dropbox.com/u/69253136/0/p
https://dl-web.dropbox.com/u/69253136/0/U
The problems I am now facing with are as following:first,when it calculate to the time=353,it occure noconvergence;second,I sample same points's value of velocity,i am sure they are wrong.I only change the files of fvsolution and fvschemes.please give me some advice to correct them.
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Old   May 22, 2012, 08:28
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Hi,

your breakup is coused by the turbulence model!
Code:
bounding k, min: 0 max: 50.8029155486 average: 1.44150802022
ExecutionTime = 126.62 s ClockTime = 141 s
bounding is not very "good" it can appear in the simulation but should stabilize while running your case.
But you have a problem with your model:
Code:
#6 Foam::incompressible::RASModels::kEpsilon::correct () in "/opt/openfoam210/platforms/linuxGccDPOpt/lib/libincompressibleRASModels.so"
Well maybe you`ve wrong BC or completely unrealistic values for k?
I would have a look at that be for trying to change the schemes!
I think you `ve got a BC-problem. If you are not sure, save your first time step and have a look at the results. There you should see where your peaks are (k, espilon, p, U ...) - maybe there is a mesh problem at all?


I would give you the advice to correct the "uniform" error. Well maybe its not a problem but you should set the files for OF correct.

Tobi


PS: Solver for k, eps.... PBiCG -- have a look at the tutorials pitzDaily
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Old   May 22, 2012, 08:34
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please give the same info as in

How to give enough info to get help

It will help
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PS. I do not do personal support, so please post in the forums.
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