[izna]

hi
i am running simpleFoam, when arriving at time =6
i get this error, can anyone please tell me what does this mean?

Time = 6

smoothSolver: Solving for Ux, Initial residual = 0.999981884042, Final residual = 0.0153174727243, No Iterations 2
smoothSolver: Solving for Uy, Initial residual = 0.999944319274, Final residual = 0.0154245506389, No Iterations 2
#0 Foam::error:rintStack(Foam::Ostream&) in "/opt/openfoam221/platforms/linuxGccDPOpt/lib/libOpenFOAM.so"
#1 Foam::sigFpe::sigHandler(int) in "/opt/openfoam221/platforms/linuxGccDPOpt/lib/libOpenFOAM.so"
#2 Uninterpreted:
#3 Foam::GAMGSolver::scale(Foam::Field<double>&, Foam::Field<double>&, Foam::lduMatrix const&, Foam::FieldField<Foam::Field, double> const&, Foam::UPtrList<Foam::lduInterfaceField const> const&, Foam::Field<double> const&, unsigned char) const in "/opt/openfoam221/platforms/linuxGccDPOpt/lib/libOpenFOAM.so"
#4 Foam::GAMGSolver::Vcycle(Foam::PtrList<Foam::lduMa trix::smoother> const&, Foam::Field<double>&, Foam::Field<double> const&, Foam::Field<double>&, Foam::Field<double>&, Foam::Field<double>&, Foam::PtrList<Foam::Field<double> >&, Foam::PtrList<Foam::Field<double> >&, unsigned char) const in "/opt/openfoam221/platforms/linuxGccDPOpt/lib/libOpenFOAM.so"
#5 Foam::GAMGSolver::solve(Foam::Field<double>&, Foam::Field<double> const&, unsigned char) const in "/opt/openfoam221/platforms/linuxGccDPOpt/lib/libOpenFOAM.so"
#6 Foam::fvMatrix<double>::solveSegregated(Foam::dict ionary const&) in "/opt/openfoam221/platforms/linuxGccDPOpt/lib/libfiniteVolume.so"
#7 Foam::fvMatrix<double>::solve(Foam::dictionary const&) in "/opt/openfoam221/platforms/linuxGccDPOpt/bin/simpleFoam"
#8
in "/opt/openfoam221/platforms/linuxGccDPOpt/bin/simpleFoam"
#9 __libc_start_main in "/lib/i386-linux-gnu/libc.so.6"
#10
in "/opt/openfoam221/platforms/linuxGccDPOpt/bin/simpleFoam"
Floating point exception (core dumped)

[nimasam]

change your fvSolution solver from GMAG to another some thing else

[izna]

can you suggest something for me?

[nimasam]

for example PCG

[izna]

Hi with PCG it works till time 642, then nothing..

Time = 642

DILUPBiCG: Solving for Ux, Initial residual = 1, Final residual = 0.0177743513091, No Iterations 2
DILUPBiCG: Solving for Uy, Initial residual = 1, Final residual = 0.0184138604988, No Iterations 2
DICPCG: Solving for p, Initial residual = 1, Final residual = 0.00818779614983, No Iterations 210
time step continuity errors : sum local = 1.112618534e+95, global = -3.29213316209e+94, cumulative = -3.29213316209e+94
#0 Foam::error:rintStack(Foam::Ostream&) in "/opt/openfoam221/platforms/linuxGccDPOpt/lib/libOpenFOAM.so"
#1 Foam::sigFpe::sigHandler(int) in "/opt/openfoam221/platforms/linuxGccDPOpt/lib/libOpenFOAM.so"
#2 Uninterpreted:
#3 Foam::multiply(Foam::Field<double>&, Foam::UList<double> const&, Foam::UList<double> const&) in "/opt/openfoam221/platforms/linuxGccDPOpt/lib/libOpenFOAM.so"
#4 void Foam::multiply<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/openfoam221/platforms/linuxGccDPOpt/lib/libincompressibleTurbulenceModel.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::tmp<Foam::GeometricField<double, Foam::fvPatchField, Foam::volMesh> > const&) in "/opt/openfoam221/platforms/linuxGccDPOpt/lib/libincompressibleRASModels.so"
#6 Foam::incompressible::RASModels::kEpsilon::correct () in "/opt/openfoam221/platforms/linuxGccDPOpt/lib/libincompressibleRASModels.so"
#7
in "/opt/openfoam221/platforms/linuxGccDPOpt/bin/simpleFoam"
#8 __libc_start_main in "/lib/i386-linux-gnu/libc.so.6"
#9
in "/opt/openfoam221/platforms/linuxGccDPOpt/bin/simpleFoam"

can you help em?

[nimasam]

your numerical solution diverges, you may want to check
1) your BCs
2) your fvSchemes
3) or using higher under relaxation

Best Regards

[izna]

yesh you are right.
It was my BC i should have put negative for speed,

Can you please tell me what indicated to you that the solution is diverging?

thanks a lot

[izna]

Time = 7

DILUPBiCG: Solving for Ux, Initial residual = 0.416537273097, Final residual = 0.0412303893953, No Iterations 1
DILUPBiCG: Solving for Uy, Initial residual = 0.241978490036, Final residual = 0.00187061060806, No Iterations 2
DICPCG: Solving for p, Initial residual = 0.167099287119, Final residual = 0.00165426055675, No Iterations 256
time step continuity errors : sum local = 0.000552039460426, global = -4.00021617388e-05, cumulative = 7.21026002287e-06
DILUPBiCG: Solving for epsilon, Initial residual = 0.125184052063, Final residual = 0.0048394018806, No Iterations 1
bounding epsilon, min: -0.455824743408 max: 675.73844313 average: 0.494146861571
DILUPBiCG: Solving for k, Initial residual = 0.141307458681, Final residual = 0.00223746528525, No Iterations 2
ExecutionTime = 83.2 s ClockTime = 85 s

Time = 8

DILUPBiCG: Solving for Ux, Initial residual = 0.192760537852, Final residual = 0.00416147789784, No Iterations 2
DILUPBiCG: Solving for Uy, Initial residual = 0.250548770977, Final residual = 0.0207270078209, No Iterations 1
DICPCG: Solving for p, Initial residual = 0.0844843814645, Final residual = 0.000800111012941, No Iterations 272
time step continuity errors : sum local = 0.000534318321906, global = 1.58871055645e-05, cumulative = 2.30973655873e-05
DILUPBiCG: Solving for epsilon, Initial residual = 0.0707423592074, Final residual = 0.00498617065599, No Iterations 1
bounding epsilon, min: -0.455824743408 max: 915.218420132 average: 0.510478965342
DILUPBiCG: Solving for k, Initial residual = 0.0918248773501, Final residual = 0.00156527744157, No Iterations 2
ExecutionTime = 93.68 s ClockTime = 95 s

is something like this converging for example?

[nimasam]

well izna
first look at your continuity

time step continuity errors : sum local = 1.112618534e+95, global = -3.29213316209e+94, cumulative = -3.29213316209e+94

it should be decreasing
However there are several ways to understand whether it converges or not.
for example your residual should be decreasing or if residuals became fixed, it should be less than an specific number
in OpenFoam, you can save your terminal print in a log file by following command:

solvername > log &

then you can use foamLog

foamLog log

to create a folder name logs which contains your residual values for each variable, then you can plot your residuals to see whether it converges or not
also there are other easier tools to plot residual, search in forum

[izna]

Time = 636

DILUPBiCG: Solving for Ux, Initial residual = 1, Final residual = 0.0126381975126, No Iterations 2
DILUPBiCG: Solving for Uy, Initial residual = 1, Final residual = 0.00971408846349, No Iterations 2
#0 Foam::error:rintStack(Foam::Ostream&) in "/opt/openfoam221/platforms/linuxGccDPOpt/lib/libOpenFOAM.so"
#1 Foam::sigFpe::sigHandler(int) in "/opt/openfoam221/platforms/linuxGccDPOpt/lib/libOpenFOAM.so"
#2 Uninterpreted:
#3 Foam:ICPreconditioner::calcReciprocalD(Foam::Fie ld<double>&, Foam::lduMatrix const&) in "/opt/openfoam221/platforms/linuxGccDPOpt/lib/libOpenFOAM.so"
#4 Foam:ICPreconditioner:ICPreconditioner(Foam::l duMatrix::solver const&, Foam::dictionary const&) in "/opt/openfoam221/platforms/linuxGccDPOpt/lib/libOpenFOAM.so"
#5 Foam::lduMatrix:reconditioner::addsymMatrixConst ructorToTable<Foam:ICPreconditioner>::New(Foam:: lduMatrix::solver const&, Foam::dictionary const&) in "/opt/openfoam221/platforms/linuxGccDPOpt/lib/libOpenFOAM.so"
#6 Foam::lduMatrix:reconditioner::New(Foam::lduMatr ix::solver const&, Foam::dictionary const&) in "/opt/openfoam221/platforms/linuxGccDPOpt/lib/libOpenFOAM.so"
#7 Foam::PCG::solve(Foam::Field<double>&, Foam::Field<double> const&, unsigned char) const in "/opt/openfoam221/platforms/linuxGccDPOpt/lib/libOpenFOAM.so"
#8 Foam::fvMatrix<double>::solveSegregated(Foam::dict ionary const&) in "/opt/openfoam221/platforms/linuxGccDPOpt/lib/libfiniteVolume.so"
#9 Foam::fvMatrix<double>::solve(Foam::dictionary const&) in "/opt/openfoam221/platforms/linuxGccDPOpt/bin/simpleFoam"
#10
in "/opt/openfoam221/platforms/linuxGccDPOpt/bin/simpleFoam"
#11 __libc_start_main in "/lib/i386-linux-gnu/libc.so.6"
#12
in "/opt/openfoam221/platforms/linuxGccDPOpt/bin/simpleFoam"

thanks a lot Nima For your patience..

In a simulation where i used PCG,with simpleFOAm, i obtain the above while iteration ...is it divergence?

[nimasam]

nope, it was not about convergence issue, i feel it's a bug in GAMG solver, i saw it before in some cases, so i suggested you to change your schemes

[izna]

hello Nima

thanks for the reply.. When doing a simualtion i notice that it say:" No finite volume option present"

Is not that a bit abnormal? I mean normlaly we try to solve using the finite volume method...so what method is it using if not finite volume?

[nimasam]

nope, it returns to new OpenFOAM file Dict called fvOptions in system directory,
it seems OpenFOAM group are going to integrate some solvers options such as MRF zone or porous media, in one dict for modification.

[izna]

Time = 1081

DILUPBiCG: Solving for Ux, Initial residual = 4.30685324415e-05, Final residual = 4.49435927907e-06, No Iterations 1
DILUPBiCG: Solving for Uy, Initial residual = 2.8262849611e-05, Final residual = 4.98771895285e-06, No Iterations 1
#0 Foam::error:rintStack(Foam::Ostream&) in "/opt/openfoam221/platforms/linuxGccDPOpt/lib/libOpenFOAM.so"
#1 Foam::sigFpe::sigHandler(int) in "/opt/openfoam221/platforms/linuxGccDPOpt/lib/libOpenFOAM.so"
#2 Uninterpreted:
#3 Foam:ICPreconditioner::calcReciprocalD(Foam::Fie ld<double>&, Foam::lduMatrix const&) in "/opt/openfoam221/platforms/linuxGccDPOpt/lib/libOpenFOAM.so"
#4 Foam:ICPreconditioner:ICPreconditioner(Foam::l duMatrix::solver const&, Foam::dictionary const&) in "/opt/openfoam221/platforms/linuxGccDPOpt/lib/libOpenFOAM.so"
#5 Foam::lduMatrix:reconditioner::addsymMatrixConst ructorToTable<Foam:ICPreconditioner>::New(Foam:: lduMatrix::solver const&, Foam::dictionary const&) in "/opt/openfoam221/platforms/linuxGccDPOpt/lib/libOpenFOAM.so"
#6 Foam::lduMatrix:reconditioner::New(Foam::lduMatr ix::solver const&, Foam::dictionary const&) in "/opt/openfoam221/platforms/linuxGccDPOpt/lib/libOpenFOAM.so"
#7 Foam::PCG::solve(Foam::Field<double>&, Foam::Field<double> const&, unsigned char) const in "/opt/openfoam221/platforms/linuxGccDPOpt/lib/libOpenFOAM.so"
#8 Foam::fvMatrix<double>::solveSegregated(Foam::dict ionary const&) in "/opt/openfoam221/platforms/linuxGccDPOpt/lib/libfiniteVolume.so"
#9 Foam::fvMatrix<double>::solve(Foam::dictionary const&) in "/opt/openfoam221/platforms/linuxGccDPOpt/bin/simpleFoam"
#10
in "/opt/openfoam221/platforms/linuxGccDPOpt/bin/simpleFoam"
#11 __libc_start_main in "/lib/i386-linux-gnu/libc.so.6"
#12
in "/opt/openfoam221/platforms/linuxGccDPOpt/bin/simpleFoam"
Floating point exception (core dumped)

HI nima..

After 1081 iterations why sudenly error? i am soo lost here..;(

[nimasam]

it seems some thing is wrong in solving Matrix , i guess you need check your mesh, because PCG is almost stable solver , maybe change your preconditioner

[izna]

hello
I am solving a 2 D case, but each time error was displayed..I am sending you my system folder can you please have a look?
I am desperate here..

https://www.dropbox.com/sh/hlwk4g3bsk1zi8p/iPm_UXOZ9k

[nimasam]

did you check your mesh witch checkMesh command?
your fvSolution setup is OK, but as you use an steady-state solver, you may want to use relaxation to converge easier

[izna]

hii\
Check mesh returns okay mesh.. no skewness or aything..

I tried pisoFoam, but after 292 iterations i obtain errors... i am honestly lost now..
please do advice... what pre cond you advice?

Time = 291

Courant Number mean: 4935712.59974 max: 116034215094
DILUPBiCG: Solving for Ux, Initial residual = 0.957923467928, Final residual = 0.957923467929, No Iterations 1001
DILUPBiCG: Solving for Uy, Initial residual = 0.96607701421, Final residual = 0.966077014211, No Iterations 1001
DICPCG: Solving for p, Initial residual = 0.973495926007, Final residual = 8.35507256458, No Iterations 1001
time step continuity errors : sum local = 147534535536, global = -38492.3870488, cumulative = -38093.6803155
DICPCG: Solving for p, Initial residual = 0.00146442993015, Final residual = 0.00453884877221, No Iterations 1001
time step continuity errors : sum local = 1.51263285697e+16, global = -5595956044.77, cumulative = -5595994138.45
DILUPBiCG: Solving for epsilon, Initial residual = 0.999997760835, Final residual = 1.15811134653e-17, No Iterations 1
bounding epsilon, min: -6.99927966831e+45 max: 8.95067608531e+43 average: -1.46762720245e+40
DILUPBiCG: Solving for k, Initial residual = 9.78905292811e-17, Final residual = 9.78905292811e-17, No Iterations 0
ExecutionTime = 10764.75 s ClockTime = 10784 s

Time = 292

Courant Number mean: 2.85956156592e+16 max: 1.87922217184e+20
#0 Foam::error:rintStack(Foam::Ostream&) in "/opt/openfoam221/platforms/linuxGccDPOpt/lib/libOpenFOAM.so"
#1 Foam::sigFpe::sigHandler(int) in "/opt/openfoam221/platforms/linuxGccDPOpt/lib/libOpenFOAM.so"
#2 Uninterpreted:
#3 Foam:ILUPreconditioner::calcReciprocalD(Foam::Fi eld<double>&, Foam::lduMatrix const&) in "/opt/openfoam221/platforms/linuxGccDPOpt/lib/libOpenFOAM.so"
#4 Foam:ILUPreconditioner:ILUPreconditioner(Foam: :lduMatrix::solver const&, Foam::dictionary const&) in "/opt/openfoam221/platforms/linuxGccDPOpt/lib/libOpenFOAM.so"
#5 Foam::lduMatrix:reconditioner::addasymMatrixCons tructorToTable<Foam:ILUPreconditioner>::New(Foam ::lduMatrix::solver const&, Foam::dictionary const&) in "/opt/openfoam221/platforms/linuxGccDPOpt/lib/libOpenFOAM.so"
#6 Foam::lduMatrix:reconditioner::New(Foam::lduMatr ix::solver const&, Foam::dictionary const&) in "/opt/openfoam221/platforms/linuxGccDPOpt/lib/libOpenFOAM.so"
#7 Foam::PBiCG::solve(Foam::Field<double>&, Foam::Field<double> const&, unsigned char) const in "/opt/openfoam221/platforms/linuxGccDPOpt/lib/libOpenFOAM.so"
#8
in "/opt/openfoam221/platforms/linuxGccDPOpt/bin/pisoFoam"
#9
in "/opt/openfoam221/platforms/linuxGccDPOpt/bin/pisoFoam"
#10
in "/opt/openfoam221/platforms/linuxGccDPOpt/bin/pisoFoam"
#11
in "/opt/openfoam221/platforms/linuxGccDPOpt/bin/pisoFoam"
#12 __libc_start_main in "/lib/i386-linux-gnu/libc.so.6"
#13
in "/opt/openfoam221/platforms/linuxGccDPOpt/bin/pisoFoam"
Floating point exception (core dumped)

[nimasam]

izna look log file:

Courant Number mean: 4935712.59974 max: 116034215094
DILUPBiCG: Solving for Ux, Initial residual = 0.957923467928, Final residual = 0.957923467929, No Iterations 1001
DILUPBiCG: Solving for Uy, Initial residual = 0.96607701421, Final residual = 0.966077014211, No Iterations 1001
DICPCG: Solving for p, Initial residual = 0.973495926007, Final residual = 8.35507256458, No Iterations 1001
time step continuity errors : sum local = 147534535536, global = -38492.3870488, cumulative = -38093.6803155
DICPCG: Solving for p, Initial residual = 0.00146442993015, Final residual = 0.00453884877221, No Iterations 1001
time step continuity errors : sum local = 1.51263285697e+16, global = -5595956044.77, cumulative = -5595994138.45
DILUPBiCG: Solving for epsilon, Initial residual = 0.999997760835, Final residual = 1.15811134653e-17, No Iterations 1
bounding epsilon, min: -6.99927966831e+45 max: 8.95067608531e+43 average: -1.46762720245e+40
DILUPBiCG: Solving for k, Initial residual = 9.78905292811e-17, Final residual = 9.78905292811e-17, No Iterations 0
ExecutionTime = 10764.75 s ClockTime = 10784 s

Time = 292

Courant Number mean: 2.85956156592e+16 max: 1.87922217184e+20

your numerical solution is diverging!
you should monitor courant number, continuity and other variables residual!


i recommend:
1- check your BC
2- off your turbulence (simulate laminar flow at first)
3- use under relaxation
4- use first order schemes

[izna]

everything is fine Nima, i checked it all.. but i think its my Boundary condition.. I am simulating in 2D my west bounday is Inlet and all threee other bounday ( ie north south and east) are Outflow.. So for this case i used
1) U folder outflow is zero gradient
2) P outflow is type fixedValue; value uniform 0;
3) k and epsilone are zero gradient
4)nut is fixed value
5) nuTilda is zero gradient

do you think those values for Outflow are fine?