--> FOAM FATAL ERROR: Maximum number of iterations exceeded
 

hi everybody,

I'm solving free convection in 3D in OpenFOAM. my model is a cubic that its bottom temperature is at 400K and the upper plane is at 300K. the sides are isolated.

I'm using buoyantPimpleFoam and when I ran it the below error appeared:

anybody knows what is the source of this error?

Thank you

The crash occurs because there is no convergence when solving for the temperature from the enthalpy using the hConst species thermo model. Have a look at the following thread for some insight into what is happening:

Declaration of function TH()

As for how to fix it, have a look at your enthalpy values and see what they are doing. It could be failing for any number of reasons:

Newton's Method - Failure Analysis

How many iterations have you run when it crahes? Do you notice anything odd about the temperature? Make your write interval smaller to try and see where the problems occur.

Dear Marco,
Thank you for your reply.
this is the full results:

You've got a lot of problems with your case setup; rho, k and epsilon are all blowing up! My guess is that paying more attention to your boundary and initial conditions will solve the issues. Have a look at the tutorial cases and see if your boundary conditions are consistent for walls and open boundaries.

Wooow!
Thanks Marco,
I'm trying to solve natural convection in a closed box. in first post I explain it. I check the boundary, they are alright.
I'm so confused! I guess this errors are originated from my meshes. I should check it.

hi
My bottom temperature is 3000K. when I reduce it to 400K there is no error!!! why?!? anybody knows?

What do you mean bottom temperature? Bottom of the room, bottom range of interpolation?

sorry, bottom of the room!!! I get results with T=1000K. but It don't work for 3000K!!!!!!!
but I think they aren't true. the convection occurs weakly, but temperature is pretty high!!!!

Sounds like its a matter of tweaking the model, maybe selecting a different species thermophysical models. I haven't done much with free convection, so you'll have to ask someone with more experience.

Maybe you can try a lower deltaT in you controlDict file.
Regards

Dear Mojtaba,
I tested it, again the convection was very weak. I solve this geometry with Fluent and it solved it correctly. but I don't understand why the temperature distribution is wrong?!?!?!? actually in my model the convection doesn't occur. the bottom plane remains at T=1000K and the rest remains T=300.

do you know what is wrong?

Dear Mostafa,
I don't have too much experience in free convection. Maybe a person with more knowledge can help you. But i suggest you to have a look at this tutorial by Abolfazl Shiri:

http://www.tfd.chalmers.se/~hani/kur...i/NC_Shiri.pdf

Regards
Mojtaba

hi everybody,

again this error appears:

what should I do?!?!?:confused: I'm trying just to solve natural convection in a cubic!!!
please Help me:(

Post your residuals plot and your controlDict file to see what happens.

here you are the contrilDict and log files

thank you Mojtaba

I could solve it by defining zeroGradient boundary condition for p and p_rgh

Hi,

I m having the same Problem with my case. I m trying to simulate a constraction in free convection. After the first Time step i get: maximum number of iterations has been exceeded. exact the sameone that Mostafa got.

can i post my case so you expert :) can take a look in it? because I tried everything and nothing seems to be working :confused:. I change the BC, the solver for AIR, the Delta, checkt the initial condition, working with other Relaxations Factores and checkMesh can find no problem with my Mesh.

My porbleme apears when OP calculate h for my Air region. the T value seems to go higher then it should be.

Please Please someone help.

to Mostafa: dose your case work now? can you please post it ?

Regards

Maybe you can use some bounded Div schemes in your fvscheme file.
Try to play with different combinations of schemes.

Try to use more bounded ones, instead of more accurate schemes. after some iterations you can change back to second order and unbounded schemes for more accuracy.

best

Hi Mojtaba,

sorry for the comend queation but i m new in OpenFoam.
what do you mean with more bounded div schemes? I m using bounded Gauss upwind for all of my div schemes. Only for div(R) and div((muEff*... i m using Gauss linear.

thank you
Best Regards

Hi all,
i got the same problem. I am using the buoyantSimpleRadiationFoam. The problems is always at the second time step, when solving the G file. Any suggestions to fix this problem?

Thank you,

Best regards

Greetings slash89,

please attach your log file, in this way we can help you much more easily

Here is the log file. I am sorry but i could not upload the file and i don't know why!

/*---------------------------------------------------------------------------*\
| ========= | |
| \\ / F ield | OpenFOAM: The Open Source CFD Toolbox |
| \\ / O peration | Version: 2.1.1 |
| \\ / A nd | Web: www.OpenFOAM.org |
| \\/ M anipulation | |
\*---------------------------------------------------------------------------*/
Build : 2.1.1-221db2718bbb
Exec : buoyantSimpleRadiationFoam -parallel
Date : Dec 05 2014
Time : 18:58:35
Host : "millegradi-nb"
PID : 4112
Case : /home/bolzo/TERMIGNONI/run/prove_solver/prova_5
nProcs : 4
Slaves :
3
(
"millegradi-nb.4113"
"millegradi-nb.4114"
"millegradi-nb.4115"
)

Pstream initialized with:
floatTransfer : 0
nProcsSimpleSum : 0
commsType : nonBlocking
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 g
Reading thermophysical properties

Selecting thermodynamics package hPsiThermo<pureMixture<constTransport<specieThermo <hConstThermo<perfectGas>>>>>
Reading field U

Reading/calculating face flux field phi

Creating turbulence model

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

Calculating field g.h

Reading field p_rgh

Selecting radiationModel P1
Selecting absorptionEmissionModel constantAbsorptionEmission
Selecting scatterModel constantScatter

SIMPLE: convergence criteria
field p_rgh tolerance 0.01
field U tolerance 0.001
field h tolerance 0.001
field G tolerance 0.001
field "(k|epsilon|omega)" tolerance 0.001


Starting time loop

Time = 1

DILUPBiCG: Solving for Ux, Initial residual = 1, Final residual = 0.00766817, No Iterations 1
DILUPBiCG: Solving for Uy, Initial residual = 1, Final residual = 0.00749132, No Iterations 1
DILUPBiCG: Solving for Uz, Initial residual = 1, Final residual = 0.00791072, No Iterations 1
DILUPBiCG: Solving for h, Initial residual = 1, Final residual = 0.00766938, No Iterations 1
DICPCG: Solving for G, Initial residual = 1, Final residual = 0.096472, No Iterations 335
DICPCG: Solving for p_rgh, Initial residual = 0.999948, Final residual = 0.00829887, No Iterations 450
time step continuity errors : sum local = 0.145697, global = -0.0018876, cumulative = -0.0018876
rho max/min : 79.6338 1.1739
DILUPBiCG: Solving for epsilon, Initial residual = 0.12008, Final residual = 0.00390459, No Iterations 1
bounding epsilon, min: -5.64769 max: 1881.23 average: 13.0219
DILUPBiCG: Solving for k, Initial residual = 1, Final residual = 0.0865008, No Iterations 1
ExecutionTime = 23.58 s ClockTime = 23 s

Time = 2

DILUPBiCG: Solving for Ux, Initial residual = 0.998573, Final residual = 0.0137559, No Iterations 1
DILUPBiCG: Solving for Uy, Initial residual = 0.999799, Final residual = 0.0141418, No Iterations 1
DILUPBiCG: Solving for Uz, Initial residual = 0.999881, Final residual = 0.0139621, No Iterations 1
DILUPBiCG: Solving for h, Initial residual = 1, Final residual = 0.013323, No Iterations 1

Thak you!

Are you sure about the BCs you exerted on your geometry? and I wanted the log file not the fist two iteration log ;)

it seems that your cumulative time step error will grow up and the range of rho variation I think is very much!!!

if you're sure about the BCs, then you should check your schemes.

Sorry but i don't understand which file you need. Do you need the G file?

Best regards

just run your case and get the log file:

and the errors appeared in your terminal.
such as: http://www.cfd-online.com/Forums/ope...tml#post375086

Hope this is what we need! :)

The problem is probably related to the pressure field. I guess you have negative pressure, so the thermophysical library crashes.

check the following:

1. check your grids, checkmesh
2. use 1st order scheme for temporal discretization
3. modify the tolerance tol_ from 1.0e-4 to something higher e.g. 1.0e-3, but this is not a good advice. thanks to dmoroian
4. at last, modify the maxIter_ from 100 to something larger. you can find the implementation process in http://www.cfd-online.com/Forums/ope...tml#post179437

hope these help you

It still does not work. At this point the problem is in the BCs. Can I upload them here?

it's the best thing you can do! ;)

Attachment 35793


Thak you!

nobody can help??

Maximum number of iterations exceeded
 

hi

i have this problem
can anyone help me?
if i change the mesh ,solve?
or if i remove the energy equation

best regards

masoud

--> FOAM FATAL ERROR:
Maximum number of iterations exceeded

From function specieThermo<Thermo>::T(scalar f, scalar T0, scalar (specieThermo<Thermo>::*F)(const scalar) const, scalar (specieThermo<Thermo>::*dFdT)(const scalar) const) const
in file /home/opencfd/OpenFOAM/OpenFOAM-2.0.1/src/thermophysicalModels/specie/lnInclude/specieThermoI.H at line 67.

Need a lot more info

hi Derek

what do you want to know?
did you see this problem later?

best regards
masoud

Hi

I got the sam problem,Can anyone solve it?
I have this problem in my project,I do anything such as mesh,Bc , ... but doesn't work.
if I find anything tell here ,please help me if the problem solve

Best Regards
Masoud

Hi Masoud,
Take a look at this:
http://openfoam.ir/questions/questio...AE%D8%B7%D8%A7

Best.