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#1 |
New Member
oum
Join Date: Feb 2017
Posts: 14
Rep Power: 9 ![]() |
Hi,
I am a new user of OF, I am simulating a rotating hydroturbine using pimpleDyMFoam but I have some issues where the simulation crashes after high Co number value and few iterations. I run the checkMesh, it is okay. If anyone can help me figure out where the problem is, please thank you. For example: Code:
Courant Number mean: 0.0665607 max: 294.314 Time = 0.0035 smoothSolver: Solving for Uz, Initial residual = 0.000988812, Final residual = 8.59295e-07, No Iterations 6 AMI: Creating addressing and weights between 18784 source faces and 18784 target faces smoothSolver: Solving for Ux, Initial residual = 0.00213788, Final residual = 1.06473e-06, No Iterations 5 AMI: Patch source sum(weights) min/max/average = 0.999999, 1.00004, 1.00001 AMI: Patch target sum(weights) min/max/average = 0.997471, 1.00004, 0.999978 smoothSolver: Solving for Uy, Initial residual = 0.00214001, Final residual = 2.03012e-06, No Iterations 4 smoothSolver: Solving for Uz, Initial residual = 0.00257939, Final residual = 1.7967e-06, No Iterations 5 PIMPLE: iteration 1 smoothSolver: Solving for Ux, Initial residual = 0.000304317, Final residual = 5.73925e-07, No Iterations 7 smoothSolver: Solving for Uy, Initial residual = 0.000301525, Final residual = 8.5824e-07, No Iterations 6 smoothSolver: Solving for Uz, Initial residual = 0.000429538, Final residual = 8.4974e-07, No Iterations 7 PIMPLE: iteration 1 smoothSolver: Solving for Ux, Initial residual = 0.0214581, Final residual = 1.67677e-05, No Iterations 3 smoothSolver: Solving for Uy, Initial residual = 0.0214571, Final residual = 1.4444e-05, No Iterations 3 smoothSolver: Solving for Uz, Initial residual = 0.0245988, Final residual = 2.12498e-05, No Iterations 3 GAMG: Solving for p, Initial residual = 0.0103925, Final residual = 9.27148e-06, No Iterations 8 time step continuity errors : sum local = 2.14296e-08, global = -2.31864e-09, cumulative = 3.61365e-07 smoothSolver: Solving for Ux, Initial residual = 0.0214581, Final residual = 1.67677e-05, No Iterations 3 smoothSolver: Solving for Uy, Initial residual = 0.0214571, Final residual = 1.4444e-05, No Iterations 3 PIMPLE: iteration 5 smoothSolver: Solving for Uz, Initial residual = 0.0245988, Final residual = 2.12498e-05, No Iterations 3 GAMG: Solving for p, Initial residual = 0.02332, Final residual = 2.00854e-05, No Iterations 7 time step continuity errors : sum local = 4.63087e-08, global = -5.40695e-09, cumulative = 3.63684e-07 PIMPLE: iteration 4 GAMG: Solving for p, Initial residual = 0.00487913, Final residual = 3.59641e-06, No Iterations 7 time step continuity errors : sum local = 8.28061e-09, global = -3.505e-09, cumulative = 3.5786e-07 smoothSolver: Solving for Ux, Initial residual = 0.000304317, Final residual = 5.73925e-07, No Iterations 7 GAMG: Solving for p, Initial residual = 0.023441, Final residual = 1.95274e-05, No Iterations 6 time step continuity errors : sum local = 4.43837e-08, global = -1.11018e-08, cumulative = 3.46758e-07 smoothSolver: Solving for Uy, Initial residual = 0.000301525, Final residual = 8.5824e-07, No Iterations 6 PIMPLE: iteration 2 smoothSolver: Solving for Uz, Initial residual = 0.000429538, Final residual = 8.4974e-07, No Iterations 7 smoothSolver: Solving for omega, Initial residual = 0.000412129, Final residual = 6.34727e-07, No Iterations 4 smoothSolver: Solving for Ux, Initial residual = 0.000718585, Final residual = 6.28164e-07, No Iterations 6 GAMG: Solving for p, Initial residual = 0.023441, Final residual = 1.95274e-05, No Iterations 6 time step continuity errors : sum local = 4.43837e-08, global = -1.11018e-08, cumulative = 3.46758e-07 smoothSolver: Solving for Uy, Initial residual = 0.000718183, Final residual = 5.84072e-07, No Iterations 6 PIMPLE: iteration 2 smoothSolver: Solving for k, Initial residual = 0.0207893, Final residual = 6.86243e-06, No Iterations 3 PIMPLE: not converged within 5 iterations smoothSolver: Solving for Uz, Initial residual = 0.000988812, Final residual = 8.59295e-07, No Iterations 6 smoothSolver: Solving for Ux, Initial residual = 0.00706966, Final residual = 4.63885e-06, No Iterations 6 ExecutionTime = 976.44 s ClockTime = 1035 s |
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#2 |
Member
Sugajen
Join Date: Jan 2012
Location: Tempe, USA
Posts: 52
Rep Power: 14 ![]() |
Hi oumnia,
Welcome to OF! Regarding your question, there could be various reasons for a high Courant number. My quick question now will be did you try setting adjustTimeStep to yes and the max Courant number to a lower value? If your answer is yes, then please do post your boundary conditions, fvSchemes, fvSolutions and other necessary data so that people who can help can get a better hold on the issue. best, Sugajen |
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#3 |
Senior Member
Oskar
Join Date: Nov 2015
Location: Poland
Posts: 184
Rep Power: 10 ![]() |
Could You show us Your 'checkMesh' report, please? Usually new users misunderstand the report.
__________________
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#4 |
New Member
oum
Join Date: Feb 2017
Posts: 14
Rep Power: 9 ![]() |
Yes, I did set adjustTimeStep to yes
I attached my boundary conditions Here is my fvSchemes: Code:
ddtSchemes { default Euler; } gradSchemes { default Gauss linear; grad(p) cellLimited Gauss linear 1; grad(U) cellLimited Gauss linear 1; } divSchemes { default none; div(phi,U) Gauss linearUpwind grad(U); div(phi,k) Gauss upwind; div(phi,omega) Gauss upwind; div((nuEff*dev2(T(grad(U))))) Gauss linear; } laplacianSchemes { default Gauss linear limited corrected 0.5; } interpolationSchemes { default linear; } snGradSchemes { default corrected; } fluxRequired { default no; pcorr ; p ; } wallDist { method meshWave; } Code:
solvers { pcorr { solver GAMG; tolerance 1e-4; relTol 0.001; nPreSweeps 0; nPostSweeps 2; smoother DICGaussSeidel; cacheAgglomeration true; nCellsInCoarsestLevel 10; agglomerator faceAreaPair; mergeLevels 1; maxIter 10; } p { $pcorr; tolerance 1e-5; relTol 0.001; maxIter 10; } pFinal { $p; tolerance 1e-6; relTol 0.001; maxIter 10; } "(U|k|omega)" { solver smoothSolver; smoother GaussSeidel; tolerance 1e-6; relTol 0.001; maxIter 20; } "(U|k|omega)Final" { solver smoothSolver; smoother GaussSeidel; tolerance 1e-6; relTol 0.001; maxIter 20; } } PIMPLE { correctPhi no; nOuterCorrectors 5; nCorrectors 1; nNonOrthogonalCorrectors 0; pRefCell 0; pRefValue 0; residualControl { U { tolerance 1e-2; relTol 0.001; } p { tolerance 1e-2; relTol 0.001; } } } relaxationFactors { fields { p 0.7; } equations { "(U|k|omega)" 0.7; "(U|k|omega)Final" 0.7; } } cache { grad(U); } |
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