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August 24, 2010, 07:57 
Max iteration exceeded

#1 
New Member
James
Join Date: Jan 2010
Posts: 6
Rep Power: 8 
Hello,
I'm having problems running a case involving relatively slow airflow (100m/s) with heat transfer. I'm trying to use rhoSimpleFoam which keeps spitting out an error for exceeding the max number of iterations. Playing with the rho max and min values and the relaxation factors seems to change how long it takes for the error to appear, but didn't solve. I assume its due to a diverging solution. I have gone back and looked at the boundary conditions several times and believe everything to be correct. Can anyone please shed some light on whats going on here and a course of action to solve it. Thanks for your help James Error: Time = 48 smoothSolver: Solving for Ux, Initial residual = 0.015928, Final residual = 0.000956812, No Iterations 4 smoothSolver: Solving for Uy, Initial residual = 0.024058, Final residual = 0.00145616, No Iterations 4 smoothSolver: Solving for Uz, Initial residual = 0.0187837, Final residual = 0.0011141, No Iterations 4 DILUPBiCG: Solving for h, Initial residual = 0.0419237, Final residual = 0.00245746, No Iterations 6 GAMG: Solving for p, Initial residual = 0.00629986, Final residual = 0.000211266, No Iterations 2 time step continuity errors : sum local = 83.3833, global = 4.52158, cumulative = 350.1 rho max/min : 1.99995 0.00792878 ExecutionTime = 10.33 s ClockTime = 11 s Time = 49 smoothSolver: Solving for Ux, Initial residual = 0.0150919, Final residual = 0.00090136, No Iterations 4 smoothSolver: Solving for Uy, Initial residual = 0.023529, Final residual = 0.00143824, No Iterations 4 smoothSolver: Solving for Uz, Initial residual = 0.0184029, Final residual = 0.00111382, No Iterations 4 DILUPBiCG: Solving for h, Initial residual = 0.0404039, Final residual = 0.00330438, No Iterations 12 > 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/james/OpenFOAM/OpenFOAM1.7.x/src/thermophysicalModels/specie/lnInclude/specieThermoI.H at line 67. FOAM aborting #0 Foam::error:rintStack(Foam::Ostream&) in "/home/james/OpenFOAM/OpenFOAM1.7.x/lib/linux64GccDPOpt/libOpenFOAM.so" #1 Foam::error::abort() in "/home/james/OpenFOAM/OpenFOAM1.7.x/lib/linux64GccDPOpt/libOpenFOAM.so" #2 Foam::hPsiThermo<Foam:ureMixture<Foam::constTran sport<Foam::specieThermo<Foam::hConstThermo<Foam:: perfectGas> > > > >::calculate() in "/home/james/OpenFOAM/OpenFOAM1.7.x/lib/linux64GccDPOpt/libbasicThermophysicalModels.so" #3 Foam::hPsiThermo<Foam:ureMixture<Foam::constTran sport<Foam::specieThermo<Foam::hConstThermo<Foam:: perfectGas> > > > >::correct() in "/home/james/OpenFOAM/OpenFOAM1.7.x/lib/linux64GccDPOpt/libbasicThermophysicalModels.so" #4 in "/home/james/OpenFOAM/OpenFOAM1.7.x/applications/bin/linux64GccDPOpt/rhoSimpleFoam" #5 __libc_start_main in "/lib64/libc.so.6" #6 at /usr/src/packages/BUILD/glibc2.11.2/csu/../sysdeps/x86_64/elf/start.S:116 Aborted 

August 24, 2010, 08:18 

#2 
Senior Member
Christian Lucas
Join Date: Aug 2009
Location: Braunschweig, Germany
Posts: 200
Rep Power: 9 
Hi,
the problem is related to the thermo physical model you're using. The problem is that the function T (class specieThermo), which uses a Newton solver to get the temperature for a given enthalpy, can't find a solution within a 100 iteration. The main reason for this problem might be that your pressure or enthalpy is out of bound. Decrease the relaxation factors, and check the pressure and enthalpy before the error occurs Regards, Christian 

August 25, 2010, 11:22 

#3 
New Member
James
Join Date: Jan 2010
Posts: 6
Rep Power: 8 
Thanks for your help chris,
I reduced the relaxation factors but hasn't seem to have solved the problem. Definitely pressure field thats going wrong but not sure how to fix. I've uploaded my case (minus the mesh), if someone wouldn't mind having a quick look to see if i'm doing something stupid it would be greatly appreciated! James 

August 26, 2010, 04:21 

#4 
New Member
James
Join Date: Jan 2010
Posts: 6
Rep Power: 8 
Fixed problem. I had a wave instability problem. I went back and looked at my relaxation factors and after some careful changes got stability.


August 26, 2010, 07:32 

#5 
Senior Member
Christian Lucas
Join Date: Aug 2009
Location: Braunschweig, Germany
Posts: 200
Rep Power: 9 
Hi,
would it be possible to upload the working case file? By "wave instability problem", what exactly do you mean? Was the flow reflected at the outlet BC? Regards, Christian 

May 9, 2011, 12:00 
FOAM FATAL ERROR: Maximum number of iterations exceeded

#6 
Senior Member
Tarak
Join Date: Aug 2010
Location: State College, PA
Posts: 106
Rep Power: 7 
Hii,
I am facing a similar problem while running rhoPisoFoam. Can someone please let me know how to avoid it? Thanks, Tarak 

August 24, 2011, 05:43 
problem in rhoPorusMRFSimpleFoam

#7 
New Member
Suhas
Join Date: Jul 2011
Location: Pune
Posts: 20
Rep Power: 7 
Hello Foamers,
I am using rhoPorousMRFSimpleFoam for compressor simulation. the mesh is came from starccm+ and checkMesh is ok. Then these are my boundary conditions. I am starting with very slow rotational velocity, i.e. w=1 rad/sec. for p inletzeroGradient, outletfixedValue, $internalField wallzeroGradient internalField uniform 2e5; for U inletfixedValue, uniform (150 0 0) outletzeroGradient, wallfixedValue, uniform (0 0 0) internalField uniform (1 10 10) for T inlettotalTemperature, T0 uniform 300, gamma 1.4 outletinletOutlet, value $internalField, inletValue $internalField wallzeroGradient, internalField uniform 298; for mut inletcalculated uniform 0, outletcalculated uniform 0, wallmutkWallFunction uniform 0, internalField uniform 0.018; for k inletfixedValue, uniform 70 outletzeroGradient wallcompressible: :kqRWallFunction uniform 7, internalField uniform 7; for epsilon inletfixedValue, uniform 19222.91 outletzeroGradient wallcompressible: :epsilonWallFunction uniform 1922.291, internalField uniform 7; for alphat inletcalculated uniform 0, outletcalculated uniform 0, wallalphatWallFunction uniform 0, internalField uniform 0; my relaxation factors from fvSolution files are p 0.1; rho 1; U 0.3; "(kepsilon)" 0.5; h 0.5; and rhomax  1.9 rhomin  0.6 and thermoType hPsiThermo<pureMixture<constTransport<specieThermo <hConstThermo<perfectGas>>>>>; mixture { specie { nMoles 1; molWeight 28.9; } thermodynamics { Cp 1007; Hf 2.544e+06; } transport { mu 0.1835e04; Pr 0.72; } } and I am getting this error after 200 iterations. > 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 (s pecieThermo<Thermo>::*dFdT)(const scalar) const) const in file /opt/software/OpenFOAM/OpenFOAM2.0.x/src/thermophysicalModels/specie/lnInclude/specieThermoI.H at line 67. FOAM aborting #0 Foam::error:rintStack(Foam::Ostream&) in "/share/openfoam/2.0/OpenFOAM/platforms/linux64Gcc45DPOpt/lib/libOpenFOAM.so" #1 Foam::error::abort() in "/share/openfoam/2.0/OpenFOAM/platforms/linux64Gcc45DPOpt/lib/libOpenFOAM.so" #2 Foam::hPsiThermo<Foam:ureMixture<Foam::constTran sport<Foam::specieThermo<Foam::hConstThermo<Foam:: perfectGas> > > > >::ca lculate() in "/share/openfoam/2.0/OpenFOAM/platforms/linux64Gcc45DPOpt/lib/libbasicThermophysicalModels.so" #3 Foam::hPsiThermo<Foam:ureMixture<Foam::constTran sport<Foam::specieThermo<Foam::hConstThermo<Foam:: perfectGas> > > > >::co rrect() in "/share/openfoam/2.0/OpenFOAM/platforms/linux64Gcc45DPOpt/lib/libbasicThermophysicalModels.so" #4 main in "/share/openfoam/2.0/OpenFOAM/platforms/linux64Gcc45DPOpt/bin/rhoPorousMRFSimpleFoam" #5 __libc_start_main in "/lib64/libc.so.6" #6 Foam::UOPstream::write(char) in "/share/openfoam/2.0/OpenFOAM/platforms/linux64Gcc45DPOpt/bin/rhoPorousMRFSimpleFoam" Abort Please tell me where I am going wrong. Is anybody using rhoPorousMRFSimpleFoam? Regards Suhas 

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