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-   -   convergence problem when use pisoFoam, LES for wind tunnel case (http://www.cfd-online.com/Forums/openfoam/72090-convergence-problem-when-use-pisofoam-les-wind-tunnel-case.html)

 Forrest_Lei January 25, 2010 10:48

convergence problem when use pisoFoam, LES for wind tunnel case

Hello foamers,
I am using pisoFoam to model a wind tunnel case, wind blowing on a small building model, both internal and external flow are modelled. Now I am having convergence problem for this LES calculation.
My mesh check results are show below (part I), I modified the les pitzDaily case for this. The calculation started ok, with Courant Number mean about 0.0021, relatively stable; Max: about 0.5, changes can be from 0.25 to 0.6 normally. Time step is 0.00001s. However, after certain timesteps, the max Courant number starts increasing gradually, after another 100 timesteps or so, all of sudden, increased to a ridiculously big number and the calculation stopped (part II shows a few time step histories). My fvScheme and fvSolution are the same as the example. Can anyone suggest me how I should manage the convergence or give me some hints where the underlying problem might be? Your comments would be much appreciated, thank you.
Regards
Forrest

----------------- part I start --------------------
Checking geometry...
Overall domain bounding box (-3.5 -5.3758e-17 -2.77785e-07) (2.48154e-24 0.8 1.2)
Mesh (non-empty, non-wedge) directions (1 1 1)
Mesh (non-empty) directions (1 1 1)
Boundary openness (5.34441e-16 1.61725e-15 -2.62598e-15) OK.
Max cell openness = 3.46613e-16 OK.
Max aspect ratio = 76.0056 OK.
Minumum face area = 2.07154e-07. Maximum face area = 0.000917946. Face area magnitudes OK.
Min volume = 1.33381e-10. Max volume = 1.35026e-05. Total volume = 3.35384. Cell volumes OK.
Mesh non-orthogonality Max: 61.7856 average: 2.95921
Non-orthogonality check OK.
Face pyramids OK.
Max skewness = 1.77896 OK.
Mesh OK.
------------- part I ends --------------------------------------

---------------- part II starts -----------------------------------
Time = 0.01271
Courant Number mean: 0.0020937 max: 0.266211
DILUPBiCG: Solving for Ux, Initial residual = 4.63219e-05, Final residual = 1.43073e-08, No Iterations 1
DILUPBiCG: Solving for Uy, Initial residual = 0.000157491, Final residual = 8.43967e-08, No Iterations 1
DILUPBiCG: Solving for Uz, Initial residual = 0.000339904, Final residual = 1.80376e-07, No Iterations 1
DICPCG: Solving for p, Initial residual = 0.00747972, Final residual = 0.000328662, No Iterations 4
time step continuity errors : sum local = 7.98063e-11, global = 1.06981e-13, cumulative = -7.66251e-10
DICPCG: Solving for p, Initial residual = 0.000495298, Final residual = 9.54513e-07, No Iterations 467
time step continuity errors : sum local = 2.31815e-13, global = -1.41083e-14, cumulative = -7.66265e-10
ExecutionTime = 12257.6 s ClockTime = 13416 s
Calculating averages
Time = 0.01272
Courant Number mean: 0.0020937 max: 0.279225
DILUPBiCG: Solving for Ux, Initial residual = 4.63096e-05, Final residual = 1.41444e-08, No Iterations 1
DILUPBiCG: Solving for Uy, Initial residual = 0.000157573, Final residual = 8.37715e-08, No Iterations 1
DILUPBiCG: Solving for Uz, Initial residual = 0.000340056, Final residual = 1.79683e-07, No Iterations 1
DICPCG: Solving for p, Initial residual = 0.00741885, Final residual = 0.000310164, No Iterations 4
time step continuity errors : sum local = 7.53338e-11, global = -1.02461e-13, cumulative = -7.66368e-10
DICPCG: Solving for p, Initial residual = 0.000466498, Final residual = 9.82048e-07, No Iterations 641
time step continuity errors : sum local = 2.38588e-13, global = -4.89605e-15, cumulative = -7.66373e-10
ExecutionTime = 12267.1 s ClockTime = 13426 s
Calculating averages
Time = 0.01273
Courant Number mean: 0.00209371 max: 0.29519
DILUPBiCG: Solving for Ux, Initial residual = 4.63311e-05, Final residual = 1.40266e-08, No Iterations 1
DILUPBiCG: Solving for Uy, Initial residual = 0.000157646, Final residual = 8.33521e-08, No Iterations 1
DILUPBiCG: Solving for Uz, Initial residual = 0.000340203, Final residual = 1.7883e-07, No Iterations 1
DICPCG: Solving for p, Initial residual = 0.00741554, Final residual = 0.000318821, No Iterations 4
time step continuity errors : sum local = 7.74663e-11, global = 2.24895e-14, cumulative = -7.6635e-10
DICPCG: Solving for p, Initial residual = 0.00047017, Final residual = 9.70856e-07, No Iterations 671
time step continuity errors : sum local = 2.35942e-13, global = 9.8275e-16, cumulative = -7.66349e-10
ExecutionTime = 12279.6 s ClockTime = 13438 s
Calculating averages
Time = 0.01274
Courant Number mean: 0.00209371 max: 0.310313
DILUPBiCG: Solving for Ux, Initial residual = 4.63345e-05, Final residual = 1.3925e-08, No Iterations 1
DILUPBiCG: Solving for Uy, Initial residual = 0.000157711, Final residual = 8.3139e-08, No Iterations 1
DILUPBiCG: Solving for Uz, Initial residual = 0.000340355, Final residual = 1.78012e-07, No Iterations 1
DICPCG: Solving for p, Initial residual = 0.00746455, Final residual = 0.000292083, No Iterations 4
time step continuity errors : sum local = 7.09822e-11, global = 3.03319e-15, cumulative = -7.66346e-10
DICPCG: Solving for p, Initial residual = 0.00044284, Final residual = 9.93709e-07, No Iterations 696
time step continuity errors : sum local = 2.41554e-13, global = -8.10546e-15, cumulative = -7.66354e-10
ExecutionTime = 12288 s ClockTime = 13447 s

Time = 0.01358
Courant Number mean: 0.0020944 max: 1.09555
DILUPBiCG: Solving for Ux, Initial residual = 0.000104529, Final residual = 7.40216e-07, No Iterations 1
DILUPBiCG: Solving for Uy, Initial residual = 0.00017705, Final residual = 5.41423e-07, No Iterations 2
DILUPBiCG: Solving for Uz, Initial residual = 0.000381853, Final residual = 5.9746e-07, No Iterations 2
DICPCG: Solving for p, Initial residual = 0.0315146, Final residual = 0.00132091, No Iterations 23
time step continuity errors : sum local = 3.94768e-10, global = -2.34649e-11, cumulative = -8.9372e-10
DICPCG: Solving for p, Initial residual = 0.011235, Final residual = 9.56973e-07, No Iterations 832
time step continuity errors : sum local = 2.89374e-13, global = -4.59523e-16, cumulative = -8.93721e-10
ExecutionTime = 13071.6 s ClockTime = 14336 s

Time = 0.01362
Courant Number mean: 0.00209513 max: 43.2669
DILUPBiCG: Solving for Ux, Initial residual = 0.000144988, Final residual = 3.94422e-06, No Iterations 8
DILUPBiCG: Solving for Uy, Initial residual = 0.000336237, Final residual = 8.91802e-06, No Iterations 10
DILUPBiCG: Solving for Uz, Initial residual = 0.000505316, Final residual = 3.00939e-06, No Iterations 9
DICPCG: Solving for p, Initial residual = 0.285304, Final residual = 0.012613, No Iterations 35
time step continuity errors : sum local = 7.27789e-09, global = 2.86231e-10, cumulative = -7.53916e-10
DICPCG: Solving for p, Initial residual = 0.912345, Final residual = 9.96687e-07, No Iterations 954
time step continuity errors : sum local = 5.17998e-12, global = 1.19195e-14, cumulative = -7.53904e-10
ExecutionTime = 13122.4 s ClockTime = 14387 s

Time = 0.01367
Courant Number mean: 5.96862e+42 max: 3.76343e+48
DILUPBiCG: Solving for Ux, Initial residual = 0.994552, Final residual = 0.994644, No Iterations 1001
DILUPBiCG: Solving for Uy, Initial residual = 0.990671, Final residual = 0.990675, No Iterations 1001
DILUPBiCG: Solving for Uz, Initial residual = 0.997551, Final residual = 0.997559, No Iterations 1001
DICPCG: Solving for p, Initial residual = 1, Final residual = 20.1103, No Iterations 1001
time step continuity errors : sum local = 7.60816e+75, global = -6.40177e+66, cumulative = -6.40177e+66
DICPCG: Solving for p, Initial residual = 2.32194e-14, Final residual = 2.32194e-14, No Iterations 0
time step continuity errors : sum local = 4.07068e+76, global = -1.31145e+70, cumulative = -1.31209e+70

-------------------------- part II ends --------------------------

 MaryBau July 14, 2011 14:00

Did you find the solution to your problem?

 Forrest_Lei July 15, 2011 04:17

Quote:
 Originally Posted by MaryBau (Post 316166) Did you find the solution to your problem?
That was long time ago and I haven't been working with openfoam for more than a year. If I remember correctly, the problem might have been the mesh, after conversion (I have to make the mesh using ICEM, save it as 'fluent' format, then convert using the tool provided by openfoam), something went wrong although the mesh checking wasn't able to pick up.

Sorry for not being helpful on this, good luck!

Forrest

 OF_NACA July 19, 2011 06:00

convergence problem with pisoFoam

Hi foamers,
I'm running a case of a steady flow around a foil (NACA 312 66) in 2D. I've some issues with the simpleFoam solver with k omega SST turbulence model. The calculation does not stop but values are totally false.
So I try to run the case with pisoFoam and I've this error message

Time = 0.0001

Courant Number mean: 0.456197 max: 236.765
DILUPBiCG: Solving for Ux, Initial residual = 1, Final residual = 3.42308e-07, No Iterations 3
DILUPBiCG: Solving for Uy, Initial residual = 1, Final residual = 5.55072e-06, No Iterations 2
DICPCG: Solving for p, Initial residual = 1, Final residual = 0.092087, No Iterations 304
time step continuity errors : sum local = 5.94242e-06, global = 5.46953e-08, cumulative = 5.46953e-08
DICPCG: Solving for p, Initial residual = 0.116726, Final residual = 9.73547e-07, No Iterations 432
time step continuity errors : sum local = 1.10727e-09, global = -3.54505e-12, cumulative = 5.46917e-08
#0 Foam::error::printStack(Foam::Ostream&) in "/usr/OpenFOAM/OpenFOAM-1.7.1/lib/linux64GccDPOpt/libOpenFOAM.so"
#1 Foam::sigFpe::sigFpeHandler(int) in "/usr/OpenFOAM/OpenFOAM-1.7.1/lib/linux64GccDPOpt/libOpenFOAM.so"
#2 __restore_rt at sigaction.c:0
#3 Foam::LimitedScheme<double, Foam::limitedLinearLimiter<Foam::NVDTVD>, Foam::limitFuncs::magSqr>::limiter(Foam::Geometric Field<double, Foam::fvPatchField, Foam::volMesh> const&) const in "/usr/OpenFOAM/OpenFOAM-1.7.1/lib/linux64GccDPOpt/libfiniteVolume.so"
#4 Foam::limitedSurfaceInterpolationScheme<double>::w eights(Foam::GeometricField<double, Foam::fvPatchField, Foam::volMesh> const&) const in "/usr/OpenFOAM/OpenFOAM-1.7.1/lib/linux64GccDPOpt/libfiniteVolume.so"
#5 Foam::fv::gaussConvectionScheme<double>::fvmDiv(Fo am::GeometricField<double, Foam::fvsPatchField, Foam::surfaceMesh> const&, Foam::GeometricField<double, Foam::fvPatchField, Foam::volMesh>&) const in "/usr/OpenFOAM/OpenFOAM-1.7.1/lib/linux64GccDPOpt/libfiniteVolume.so"
#6 Foam::tmp<Foam::fvMatrix<double> > Foam::fvm::div<double>(Foam::GeometricField<double , Foam::fvsPatchField, Foam::surfaceMesh> const&, Foam::GeometricField<double, Foam::fvPatchField, Foam::volMesh>&, Foam::word const&) in "/usr/OpenFOAM/OpenFOAM-1.7.1/lib/linux64GccDPOpt/libincompressibleRASModels.so"
#7 Foam::tmp<Foam::fvMatrix<double> > Foam::fvm::div<double>(Foam::GeometricField<double , Foam::fvsPatchField, Foam::surfaceMesh> const&, Foam::GeometricField<double, Foam::fvPatchField, Foam::volMesh>&) in "/usr/OpenFOAM/OpenFOAM-1.7.1/lib/linux64GccDPOpt/libincompressibleRASModels.so"
#8 Foam::incompressible::RASModels::kOmegaSST::correc t() in "/usr/OpenFOAM/OpenFOAM-1.7.1/lib/linux64GccDPOpt/libincompressibleRASModels.so"
#9 main in "/usr/OpenFOAM/OpenFOAM-1.7.1/applications/bin/linux64GccDPOpt/pisoFoam"
#10 __libc_start_main in "/lib64/libc.so.6"
#11 Foam::regIOobject::writeObject(Foam::IOstream::str eamFormat, Foam::IOstream::versionNumber, Foam::IOstream::compressionType) const in "/usr/OpenFOAM/OpenFOAM-1.7.1/applications/bin/linux64GccDPOpt/pisoFoam"

Can you help me ?? I've run exactly the same case with simpleFoam and Spalart Allmaras and the results were quite good, but I need the results with K omega SST turbulence model to validate the case !

Thanks in advance !

MA

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