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-   -   Error with simpleFoam (http://www.cfd-online.com/Forums/openfoam/82055-error-simplefoam.html)

bego November 15, 2010 07:32

Error with simpleFoam
 
Hello!
I have a problem using simpleFoam, my mesh is an airfoil, I try to do the same that in the tutorial Allmaras, but I have the following mistake:

Time = 9

smoothSolver: Solving for Ux, Initial residual = 0.59657, Final residual = 0.000670198, No Iterations 4
smoothSolver: Solving for Uy, Initial residual = 0.599867, Final residual = 0.00131049, No Iterations 4
GAMG: Solving for p, Initial residual = 1, Final residual = 6.64895e-16, No Iterations 1
time step continuity errors : sum local = 2.65073e+28, global = -2.14488e+15, cumulative = -2.14488e+15
smoothSolver: Solving for nuTilda, Initial residual = 0.750679, Final residual = 1.36905e+10, No Iterations 1000
ExecutionTime = 8.64 s ClockTime = 11 s

Time = 10

smoothSolver: Solving for Ux, Initial residual = 0.996082, Final residual = 0.00471603, No Iterations 2
smoothSolver: Solving for Uy, Initial residual = 0.996082, Final residual = 0.00471603, No Iterations 2
GAMG: Solving for p, Initial residual = 1, Final residual = 0.0585277, No Iterations 1
time step continuity errors : sum local = 1.96112e+71, global = -8.59522e+54, cumulative = -8.59522e+54
#0 Foam::error::printStack(Foam::Ostream&) in "/home/bego/OpenFOAM/OpenFOAM-1.6/lib/linuxGccDPOpt/libOpenFOAM.so"
#1 Foam::sigFpe::sigFpeHandler(int) in "/home/bego/OpenFOAM/OpenFOAM-1.6/lib/linuxGccDPOpt/libOpenFOAM.so"
#2 Uninterpreted:
#3 Foam::GaussSeidelSmoother::smooth(Foam::word const&, Foam::Field<double>&, Foam::lduMatrix const&, Foam::Field<double> const&, Foam::FieldField<Foam::Field, double> const&, Foam::UPtrList<Foam::lduInterfaceField const> const&, unsigned char, int) in "/home/bego/OpenFOAM/OpenFOAM-1.6/lib/linuxGccDPOpt/libOpenFOAM.so"
#4 Foam::GaussSeidelSmoother::smooth(Foam::Field<doub le>&, Foam::Field<double> const&, unsigned char, int) const in "/home/bego/OpenFOAM/OpenFOAM-1.6/lib/linuxGccDPOpt/libOpenFOAM.so"
#5 Foam::smoothSolver::solve(Foam::Field<double>&, Foam::Field<double> const&, unsigned char) const in "/home/bego/OpenFOAM/OpenFOAM-1.6/lib/linuxGccDPOpt/libOpenFOAM.so"
#6 Foam::fvMatrix<double>::solve(Foam::dictionary const&) in "/home/bego/OpenFOAM/OpenFOAM-1.6/lib/linuxGccDPOpt/libfiniteVolume.so"
#7 Foam::lduMatrix::solverPerformance Foam::solve<double>(Foam::tmp<Foam::fvMatrix<doubl e> > const&) in "/home/bego/OpenFOAM/OpenFOAM-1.6/lib/linuxGccDPOpt/libincompressibleRASModels.so"
#8 Foam::incompressible::RASModels::SpalartAllmaras:: correct() in "/home/bego/OpenFOAM/OpenFOAM-1.6/lib/linuxGccDPOpt/libincompressibleRASModels.so"
#9 main in "/home/bego/OpenFOAM/OpenFOAM-1.6/applications/bin/linuxGccDPOpt/simpleFoam"
#10 __libc_start_main in "/lib/tls/i686/cmov/libc.so.6"
#11 _start at /usr/src/packages/BUILD/glibc-2.9/csu/../sysdeps/i386/elf/start.S:122
Exepción de coma flotante

It is an error due the mesh?
Thanks!

jhoepken November 15, 2010 08:09

What kind of mesh are you using? Without any information on your mesh, it is quite hard to tell, but I've got the feeling that your boundary conditions are defined incorrectly. This is likely to be the reason for the massively increasing time step continuity errors.

Jens

bego November 15, 2010 10:28

Hello Jens,
First, thanks for your quickly repply, and now I go to tell you how is my mesh. My mesh is an airfoil inside an elipse and both in a square. The air velocity is 14 m/s in x direction. My boundary conditions are inlet (up, down and left) freestream, fixedWalls (the airfoil) fixedValue (0 0 0) and outlet is the same that inlet. The pressure is zeroGradient in the fixedWalls and freestreamPressure in the outlet and in the inlet.
If you need more information, I can send you my mesh and the boundary condictions to your mail.
Thank, Regards

Bego

nakul November 15, 2010 23:15

Hi,
Take a look at your Initial Conditions. You may have initialised some field with 0 which might be causing problems. Change it.

bego November 16, 2010 04:04

Hi,

Thanks Nakul, do you have any idea? because I change my initial condictions some times and the results were the same, I can't find the solution.

Regards,

Bego

jhoepken November 16, 2010 05:20

Could you just post the contents of your boundary condition files (0/*)?

nakul November 16, 2010 05:51

Hi
Here "initial conditions" are not as we understand them conventionally.
They are just some initial value for each cell of your mesh becuse the declaration of fields P,T,U in the code requires specification of some initlal value all over the mesh.

These values don't affect your final solution because final solution is obtained numerically depending upon your solver. It is independent of this so called "initial condition".
So your getting same results is expected.

bego November 16, 2010 06:55

1 Attachment(s)
Hi,
Here are my files in 0 directory.
If someone can see some mistake, please say me what is.
Thanks, regards

Bego

jhoepken November 16, 2010 09:46

First of all, I'm currently using the 1.5-dev version and have no experience with the boundary conditions in 1.6. With having said that the following remarks came up to my mind:
  • You have defined the velocity at the inlet and outlet with this freestream BC. From my understanding, fixing the velocity at the inlet and outlet is not such a great idea. Try to use a zeroGradient BC at the outlet.
  • Same for the pressure. Try to fix the pressure at the outlet and use a zeroGradient at the inlet.
  • Turbulent properties should be adjusted accordingly.

I hope this helps,
Jens

bego November 16, 2010 11:59

Hi!

Thanks to all, and to Martin.
With all your messages I change some things in my Boundary condictions (freestreeam) and the most important (i think) the simplegrading in the mesh, and now my computer is iterating, now I can have all the results that I need. Thank you very much :)
You should continue helping more new members, your job in this forum is very good

Best regards,

Bego

jhoepken November 17, 2010 03:06

Glad to hear that we could help. It would be nice if you could post the changes you've applied to your BCs, since this will help others in the future that are facing the same issues.
Just out of interest, what was wrong with your mesh? I suppose you've used blockMesh to create it, as you've mentioned the simpleGrading?


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