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#1 |
New Member
Petar Zivkovic
Join Date: Feb 2011
Posts: 6
Rep Power: 16 ![]() |
Hi foamers! hope someone has solution for my problem because i don't know what is going on with my model!
![]() First of all i have to mention that i modeled 3D rectangular pipe,unsteady laminar flow, and simulation went fine after some tweaking ... i got stable solution in this case but as soon as i change geometry (with same p,U,boundery fields,fvSolution,fvSchemas...etc) i can't tweak model to convergent. ![]() Definition of the problem: ![]() This is how I modeled it: ![]() My input files: -blockMeshDict: Code:
// * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * // convertToMeters 0.1; vertices ( (-0.15 0 -0.15) (0.15 0 -0.15) (0.15 0 0.15) (-0.15 0 0.15) (-0.35355 0 -0.35355) (0.35355 0 -0.35355) (0.35355 0 0.35355) (-0.35355 0 0.35355) (-0.15 10 -0.15) (0.15 10 -0.15) (0.15 10 0.15) (-0.15 10 0.15) (-0.35355 10 -0.35355) (0.35355 10 -0.35355) (0.35355 10 0.35355) (-0.35355 10 0.35355) ); blocks ( hex (0 3 2 1 8 11 10 9) (10 10 50) simpleGrading (1 1 1) hex (0 1 5 4 8 9 13 12) (10 10 50) simpleGrading (1 1 1) hex (1 2 6 5 9 10 14 13) (10 10 50) simpleGrading (1 1 1) hex (2 3 7 6 10 11 15 14) (10 10 50) simpleGrading (1 1 1) hex (3 0 4 7 11 8 12 15) (10 10 50) simpleGrading (1 1 1) ); edges ( arc 4 5 (0 0 -0.5) arc 5 6 (0.5 0 0) arc 6 7 (0 0 0.5) arc 7 4 (-0.5 0 0) arc 12 13 (0 10 -0.5) arc 13 14 (0.5 10 0) arc 14 15 (0 10 0.5) arc 15 12 (-0.5 10 0) ); patches ( patch inlet ( (0 3 2 1) (0 1 5 4) (1 2 6 5) (2 3 7 6) (3 0 4 7) ) patch outlet ( (8 9 10 11) (8 12 13 9) (9 13 14 10) (10 14 15 11) (11 15 12 8) ) wall walls ( (4 5 13 12) (5 6 14 13) (6 7 15 14) (7 4 12 15) ) ); mergePatchPairs ( ); // ************************************************************************* // Code:
// * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * // application icoFoam; startFrom startTime; startTime 0; stopAt endTime; endTime 30; deltaT 1; writeControl timeStep; writeInterval 1; purgeWrite 0; writeFormat ascii; writePrecision 6; writeCompression uncompressed; timeFormat general; timePrecision 6; runTimeModifiable yes; // ************************************************************************* // Code:
// * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * // ddtSchemes { default Euler; // default steadyState; } gradSchemes { default Gauss linear; grad(p) Gauss linear; } divSchemes { default none; div(phi,U) Gauss linear; } laplacianSchemes { default none; laplacian(nu,U) Gauss linear corrected; laplacian((1|A(U)),p) Gauss linear corrected; } interpolationSchemes { default linear; interpolate(HbyA) linear; } snGradSchemes { default corrected; } fluxRequired { default no; p ; } // ************************************************************************* // Code:
solvers { p { solver PCG; preconditioner DIC; tolerance 1e-06; reTol 0; } U { solver PBiCG; preconditioner DILU; tolerance 1e-05; relTol 0; } } PISO { nCorrectors 2; nNonOrthogonalCorrectors 0; pRefCell 0; pRefValue 0; } // ************************************************************************* // Code:
dimensions [0 2 -2 0 0 0 0]; internalField uniform 0; boundaryField { inlet { type zeroGradient; } outlet { type fixedValue; value uniform 0; } walls { type zeroGradient; } } Code:
dimensions [0 1 -1 0 0 0 0]; internalField uniform (0 0 0); boundaryField { inlet { type fixedValue; value uniform (0 1 0); } outlet { type zeroGradient; } walls { type fixedValue; value uniform (0 0 0); } } really can't find problem...maybe icoFoam is not solver that i should use for this problem...any sugestion would be great! finally these errors and results i get on calculation: Code:
Create time Create mesh for time = 0 Reading transportProperties Reading field p Reading field U Reading/calculating face flux field phi Starting time loop Time = 1 Courant Number mean: 0 max: 100 DILUPBiCG: Solving for Ux, Initial residual = 0, Final residual = 0, No Iterations 0 DILUPBiCG: Solving for Uy, Initial residual = 1, Final residual = 7.24921e-06, No Iterations 35 DILUPBiCG: Solving for Uz, Initial residual = 0, Final residual = 0, No Iterations 0 DICPCG: Solving for p, Initial residual = 1, Final residual = 9.26667e-07, No Iterations 151 time step continuity errors : sum local = 9.26667e-07, global = 8.46286e-09, cumulative = 8.46286e-09 DICPCG: Solving for p, Initial residual = 0.00918897, Final residual = 9.76998e-07, No Iterations 136 time step continuity errors : sum local = 9.97464e-05, global = -9.91256e-07, cumulative = -9.82793e-07 ExecutionTime = 1.41 s ClockTime = 2 s Time = 2 Courant Number mean: 4.98906 max: 143.985 DILUPBiCG: Solving for Ux, Initial residual = 0.751531, Final residual = 9.97711e-06, No Iterations 28 DILUPBiCG: Solving for Uy, Initial residual = 0.313552, Final residual = 8.39474e-06, No Iterations 29 DILUPBiCG: Solving for Uz, Initial residual = 0.75153, Final residual = 7.57783e-06, No Iterations 29 DICPCG: Solving for p, Initial residual = 0.49221, Final residual = 8.38074e-07, No Iterations 147 time step continuity errors : sum local = 1.2671e-05, global = -8.75128e-09, cumulative = -9.91545e-07 DICPCG: Solving for p, Initial residual = 0.0117698, Final residual = 7.11563e-07, No Iterations 137 time step continuity errors : sum local = 0.000408209, global = 2.92362e-06, cumulative = 1.93208e-06 ExecutionTime = 2.49 s ClockTime = 3 s Time = 3 Courant Number mean: 26.4226 max: 916.486 DILUPBiCG: Solving for Ux, Initial residual = 0.809749, Final residual = 9.30861e-06, No Iterations 31 DILUPBiCG: Solving for Uy, Initial residual = 0.389871, Final residual = 7.63744e-06, No Iterations 40 DILUPBiCG: Solving for Uz, Initial residual = 0.809748, Final residual = 9.34365e-06, No Iterations 36 DICPCG: Solving for p, Initial residual = 0.604599, Final residual = 9.48499e-07, No Iterations 147 time step continuity errors : sum local = 8.65678e-05, global = 1.26445e-07, cumulative = 2.05852e-06 DICPCG: Solving for p, Initial residual = 0.0148976, Final residual = 7.70586e-07, No Iterations 137 time step continuity errors : sum local = 0.00252944, global = -1.84451e-05, cumulative = -1.63866e-05 ExecutionTime = 3.67 s ClockTime = 4 s Time = 4 Courant Number mean: 147.201 max: 4510.08 DILUPBiCG: Solving for Ux, Initial residual = 0.77792, Final residual = 9.67807e-06, No Iterations 73 DILUPBiCG: Solving for Uy, Initial residual = 0.489883, Final residual = 5.18925e-06, No Iterations 73 DILUPBiCG: Solving for Uz, Initial residual = 0.77792, Final residual = 6.03916e-06, No Iterations 73 DICPCG: Solving for p, Initial residual = 0.694876, Final residual = 8.19978e-07, No Iterations 148 time step continuity errors : sum local = 0.000558808, global = 2.33549e-06, cumulative = -1.40511e-05 DICPCG: Solving for p, Initial residual = 0.0226691, Final residual = 6.59866e-07, No Iterations 139 time step continuity errors : sum local = 0.0122011, global = 9.60505e-05, cumulative = 8.19994e-05 ExecutionTime = 5.32 s ClockTime = 5 s . . . Time = 14 Courant Number mean: 2.95062e+86 max: 2.42912e+89 DILUPBiCG: Solving for Ux, Initial residual = 0.998523, Final residual = 1.01741e+07, No Iterations 1001 DILUPBiCG: Solving for Uy, Initial residual = 0.994646, Final residual = 2.2903, No Iterations 1001 DILUPBiCG: Solving for Uz, Initial residual = 0.999568, Final residual = 69.2939, No Iterations 1001 DICPCG: Solving for p, Initial residual = 1, Final residual = 35.9498, No Iterations 1001 time step continuity errors : sum local = 1.53483e+98, global = -3.01763e+92, cumulative = -3.01763e+92 DICPCG: Solving for p, Initial residual = 0.950592, Final residual = 54.6822, No Iterations 1001 time step continuity errors : sum local = 2.09996e+101, global = -1.03985e+97, cumulative = -1.03988e+97 ExecutionTime = 142.67 s ClockTime = 143 s Time = 15 Courant Number mean: 1.99707e+101 max: 2.02545e+104 #0 Foam::error::printStack(Foam::Ostream&) in "/opt/openfoam171/lib/linuxGccDPOpt/libOpenFOAM.so" #1 Foam::sigFpe::sigFpeHandler(int) in "/opt/openfoam171/lib/linuxGccDPOpt/libOpenFOAM.so" #2 Uninterpreted: #3 Foam::PBiCG::solve(Foam::Field<double>&, Foam::Field<double> const&, unsigned char) const in "/opt/openfoam171/lib/linuxGccDPOpt/libOpenFOAM.so" #4 in "/opt/openfoam171/applications/bin/linuxGccDPOpt/icoFoam" #5 in "/opt/openfoam171/applications/bin/linuxGccDPOpt/icoFoam" #6 __libc_start_main in "/lib/tls/i686/cmov/libc.so.6" #7 in "/opt/openfoam171/applications/bin/linuxGccDPOpt/icoFoam" Floating point exception ![]() ![]() ![]() ![]() Thanks in advance...my CFD knowledge was based on basics of Finite Elements method...so Finite Volumes is something new for me...so sorry for some stupid mistakes if i made using OpenFOAM! regards! Petar Zivkovic |
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#2 |
Senior Member
Martin
Join Date: Oct 2009
Location: Aachen, Germany
Posts: 255
Rep Power: 22 ![]() |
Hi Petar,
reduce deltaT in system/controlDict to a much lower value, say 0.001, and try again. Martin |
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#3 |
New Member
Petar Zivkovic
Join Date: Feb 2011
Posts: 6
Rep Power: 16 ![]() |
Hi Matin,
Thanx for quick replay... but same problem occurred: Code:
Time = 0.015 Courant Number mean: 15.6518 max: 277.137 DILUPBiCG: Solving for Ux, Initial residual = 0.745384, Final residual = 8.16797e-06, No Iterations 53 DILUPBiCG: Solving for Uy, Initial residual = 0.78606, Final residual = 8.31362e-06, No Iterations 50 DILUPBiCG: Solving for Uz, Initial residual = 0.745302, Final residual = 5.90854e-06, No Iterations 50 DICPCG: Solving for p, Initial residual = 0.904914, Final residual = 8.3528e-07, No Iterations 227 time step continuity errors : sum local = 6.3841e-05, global = -1.01036e-07, cumulative = -3.16388e-07 DICPCG: Solving for p, Initial residual = 0.713999, Final residual = 9.34143e-07, No Iterations 221 time step continuity errors : sum local = 0.000113492, global = -2.62634e-08, cumulative = -3.42651e-07 ExecutionTime = 17.02 s ClockTime = 17 s Time = 0.016 Courant Number mean: 69.3057 max: 50974.2 DILUPBiCG: Solving for Ux, Initial residual = 0.999403, Final residual = 0.0429228, No Iterations 1001 DILUPBiCG: Solving for Uy, Initial residual = 0.998282, Final residual = 0.426477, No Iterations 1001 DILUPBiCG: Solving for Uz, Initial residual = 0.999378, Final residual = 0.0676183, No Iterations 1001 DICPCG: Solving for p, Initial residual = 0.979382, Final residual = 8.03998e-07, No Iterations 762 time step continuity errors : sum local = 0.00285593, global = 2.08686e-06, cumulative = 1.7442e-06 DICPCG: Solving for p, Initial residual = 0.993121, Final residual = 5.441e-07, No Iterations 869 time step continuity errors : sum local = 0.368197, global = 0.00145017, cumulative = 0.00145192 ExecutionTime = 33.06 s ClockTime = 33 s Time = 0.017 Courant Number mean: 2.25409e+06 max: 1.33605e+10 DILUPBiCG: Solving for Ux, Initial residual = 1, Final residual = 1.26774, No Iterations 1001 DILUPBiCG: Solving for Uy, Initial residual = 1, Final residual = 6.16202, No Iterations 1001 DILUPBiCG: Solving for Uz, Initial residual = 1, Final residual = 14331.8, No Iterations 1001 DICPCG: Solving for p, Initial residual = 1, Final residual = 2.86475, No Iterations 1001 time step continuity errors : sum local = 5.61093e+18, global = 3.57396e+12, cumulative = 3.57396e+12 DICPCG: Solving for p, Initial residual = 0.998461, Final residual = 6.10091, No Iterations 1001 time step continuity errors : sum local = 2.83525e+22, global = -7.04584e+16, cumulative = -7.04548e+16 ExecutionTime = 49.9 s ClockTime = 51 s Time = 0.018 Courant Number mean: 2.82832e+22 max: 3.0603e+25 DILUPBiCG: Solving for Ux, Initial residual = 0.998746, Final residual = 34.4554, No Iterations 1001 DILUPBiCG: Solving for Uy, Initial residual = 0.997935, Final residual = 1.09843, No Iterations 1001 DILUPBiCG: Solving for Uz, Initial residual = 0.999978, Final residual = 5.21295, No Iterations 1001 DICPCG: Solving for p, Initial residual = 1, Final residual = 994.164, No Iterations 1001 time step continuity errors : sum local = 9.01643e+34, global = -1.1094e+25, cumulative = -1.1094e+25 DICPCG: Solving for p, Initial residual = 0.854007, Final residual = 2.57049, No Iterations 1001 time step continuity errors : sum local = 1.51861e+36, global = -5.055e+28, cumulative = -5.05611e+28 ExecutionTime = 68.06 s ClockTime = 70 s Time = 0.019 Courant Number mean: 1.47917e+36 max: 6.46245e+39 DILUPBiCG: Solving for Ux, Initial residual = 0.99976, Final residual = 1.32634, No Iterations 1001 DILUPBiCG: Solving for Uy, Initial residual = 0.999817, Final residual = 2.27595, No Iterations 1001 DILUPBiCG: Solving for Uz, Initial residual = 0.999836, Final residual = 1.46444, No Iterations 1001 DICPCG: Solving for p, Initial residual = 1, Final residual = 14.1995, No Iterations 1001 time step continuity errors : sum local = 1.57509e+45, global = -5.09557e+40, cumulative = -5.09557e+40 DICPCG: Solving for p, Initial residual = 0.961166, Final residual = 1.84414, No Iterations 1001 time step continuity errors : sum local = 1.29718e+47, global = 5.31671e+42, cumulative = 5.26575e+42 ExecutionTime = 85.08 s ClockTime = 87 s Time = 0.02 Courant Number mean: 1.13079e+47 max: 1.72878e+50 DILUPBiCG: Solving for Ux, Initial residual = 0.999672, Final residual = 3.36115, No Iterations 1001 DILUPBiCG: Solving for Uy, Initial residual = 0.999739, Final residual = 1.97782, No Iterations 1001 DILUPBiCG: Solving for Uz, Initial residual = 0.999953, Final residual = 1.26137, No Iterations 1001 DICPCG: Solving for p, Initial residual = 1, Final residual = 26.5917, No Iterations 1001 time step continuity errors : sum local = 5.52811e+54, global = -1.50009e+47, cumulative = -1.50004e+47 DICPCG: Solving for p, Initial residual = 0.968712, Final residual = 3.96145, No Iterations 1001 time step continuity errors : sum local = 6.76349e+56, global = 4.68529e+51, cumulative = 4.68514e+51 ExecutionTime = 102.04 s ClockTime = 104 s Time = 0.021 Courant Number mean: 6.15008e+56 max: 1.0711e+60 DILUPBiCG: Solving for Ux, Initial residual = 0.999863, Final residual = 2.39706, No Iterations 1001 DILUPBiCG: Solving for Uy, Initial residual = 0.999311, Final residual = 2.89499, No Iterations 1001 DILUPBiCG: Solving for Uz, Initial residual = 0.999239, Final residual = 9.1686, No Iterations 1001 DICPCG: Solving for p, Initial residual = 1, Final residual = 6.74239, No Iterations 1001 time step continuity errors : sum local = 9.93366e+62, global = 8.94398e+59, cumulative = 8.94398e+59 DICPCG: Solving for p, Initial residual = 0.969226, Final residual = 5.91848, No Iterations 1001 time step continuity errors : sum local = 1.60358e+65, global = -3.91343e+61, cumulative = -3.82399e+61 ExecutionTime = 118.84 s ClockTime = 121 s Time = 0.022 Courant Number mean: 1.4642e+65 max: 1.56676e+68 DILUPBiCG: Solving for Ux, Initial residual = 0.999892, Final residual = 14.4943, No Iterations 1001 DILUPBiCG: Solving for Uy, Initial residual = 0.997566, Final residual = 314.253, No Iterations 1001 DILUPBiCG: Solving for Uz, Initial residual = 0.999563, Final residual = 47.8097, No Iterations 1001 DICPCG: Solving for p, Initial residual = 1, Final residual = 6.72161, No Iterations 1001 time step continuity errors : sum local = 2.74648e+72, global = 3.28068e+68, cumulative = 3.28068e+68 DICPCG: Solving for p, Initial residual = 0.994044, Final residual = 1.4551, No Iterations 1001 time step continuity errors : sum local = 6.07386e+74, global = -3.00558e+70, cumulative = -2.97277e+70 ExecutionTime = 135.7 s ClockTime = 139 s Time = 0.023 Courant Number mean: 4.83037e+74 max: 2.49651e+78 DILUPBiCG: Solving for Ux, Initial residual = 0.999758, Final residual = 1.13815, No Iterations 1001 DILUPBiCG: Solving for Uy, Initial residual = 0.999584, Final residual = 6.9745, No Iterations 1001 DILUPBiCG: Solving for Uz, Initial residual = 0.999761, Final residual = 1.2188, No Iterations 1001 DICPCG: Solving for p, Initial residual = 1, Final residual = 4.16214, No Iterations 1001 time step continuity errors : sum local = 7.19249e+80, global = 3.93959e+77, cumulative = 3.93959e+77 DICPCG: Solving for p, Initial residual = 0.974832, Final residual = 1.65162, No Iterations 1001 time step continuity errors : sum local = 5.25285e+82, global = 4.10531e+78, cumulative = 4.49927e+78 ExecutionTime = 153.07 s ClockTime = 157 s Time = 0.024 Courant Number mean: 4.6552e+82 max: 5.73544e+85 DILUPBiCG: Solving for Ux, Initial residual = 0.999591, Final residual = 45.7348, No Iterations 1001 DILUPBiCG: Solving for Uy, Initial residual = 0.996466, Final residual = 20.3214, No Iterations 1001 DILUPBiCG: Solving for Uz, Initial residual = 0.998556, Final residual = 7.91727, No Iterations 1001 DICPCG: Solving for p, Initial residual = 1, Final residual = 1.49843, No Iterations 1001 time step continuity errors : sum local = 6.52806e+88, global = -2.50005e+84, cumulative = -2.50005e+84 DICPCG: Solving for p, Initial residual = 0.994329, Final residual = 47.8821, No Iterations 1001 time step continuity errors : sum local = 2.26097e+92, global = -1.25671e+88, cumulative = -1.25696e+88 ExecutionTime = 170.12 s ClockTime = 174 s Time = 0.025 Courant Number mean: 2.18709e+92 max: 1.36393e+95 DILUPBiCG: Solving for Ux, Initial residual = 0.998666, Final residual = 9754.69, No Iterations 1001 DILUPBiCG: Solving for Uy, Initial residual = 0.997946, Final residual = 7535.41, No Iterations 1001 DILUPBiCG: Solving for Uz, Initial residual = 0.999833, Final residual = 303.156, No Iterations 1001 #0 Foam::error::printStack(Foam::Ostream&) in "/opt/openfoam171/lib/linuxGccDPOpt/libOpenFOAM.so" #1 Foam::sigFpe::sigFpeHandler(int) in "/opt/openfoam171/lib/linuxGccDPOpt/libOpenFOAM.so" #2 Uninterpreted: #3 Foam::PCG::solve(Foam::Field<double>&, Foam::Field<double> const&, unsigned char) const in "/opt/openfoam171/lib/linuxGccDPOpt/libOpenFOAM.so" #4 Foam::fvMatrix<double>::solve(Foam::dictionary const&) in "/opt/openfoam171/lib/linuxGccDPOpt/libfiniteVolume.so" #5 in "/opt/openfoam171/applications/bin/linuxGccDPOpt/icoFoam" #6 __libc_start_main in "/lib/tls/i686/cmov/libc.so.6" #7 in "/opt/openfoam171/applications/bin/linuxGccDPOpt/icoFoam" Floating point exception ![]() This is basic example...there should no be problem solving this... I'm just afraid that i'm doing something wrong on basic stuff...(mesh or something like that)...but checkMesh returns "mesh OK".. ![]() |
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#4 |
Senior Member
Martin
Join Date: Oct 2009
Location: Aachen, Germany
Posts: 255
Rep Power: 22 ![]() |
Hi Petar,
your case works fine for me, tested on 1.6.x and 1.6-ext... can you try the attached case? As a general rule you should keep the max courant number below 0.5 by choosing an appropriate time step. The rest of your settings seem to be fine. Best regards Martin |
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#5 |
New Member
Petar Zivkovic
Join Date: Feb 2011
Posts: 6
Rep Power: 16 ![]() |
Thanks a lot for your effort martin...you gave me direction for solving my problem...i'm abuout to find out what you have done so i'll try to modify my files and see if i can tweak it...(it seems you have added some extra parameters and files then I have)...
your example works fine...it seems that it was problem with viscosity and time step at the same time... tnx a lot! if i had some questions or suggestions that may help someone in future, i'll post it here! Petar. ![]() |
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