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May 10, 2010, 03:54 
two Phase column simulation

#1 
New Member
Benjamin
Join Date: Jan 2010
Posts: 9
Rep Power: 8 
Hello, I am trying to simulate a two phase (airwater) column. Initially, there is water in the column until the level of 450 mm and the rest is air. Only air is injecting in the column through the bottom of it. My overall domain is (0 0 0) (200 700 50). I have used setFields to set the initial water level as follows:
defaultFieldValues ( volScalarFieldValue alpha 1 ); regions ( boxToCell { box (0 0 0) (200 450 50); fieldValues ( volScalarFieldValue alpha 0 ); } ); I attach here the 0, constant and system directories. This case is similar to the bubble plume case in Henrik Rusche tesis. I have used twoPhaseEulerFoam to solve it, but always the solver fails. These are the last steps of my simulation: Time = 0.791 DILUPBiCG: Solving for alpha, Initial residual = 2.63349e07, Final residual = 1.86978e16, No Iterations 1 Dispersed phase volume fraction = 0.349989 Min(alpha) = 2.24462e10 Max(alpha) = 1 DILUPBiCG: Solving for alpha, Initial residual = 4.74634e11, Final residual = 4.74634e11, No Iterations 0 Dispersed phase volume fraction = 0.349989 Min(alpha) = 2.24462e10 Max(alpha) = 1 GAMG: Solving for p, Initial residual = 0.986187, Final residual = 5.73366e09, No Iterations 17 time step continuity errors : sum local = 1.40345e05, global = 1.79727e07, cumulative = 2.10044e05 GAMG: Solving for p, Initial residual = 1.22598e05, Final residual = 3.53858e09, No Iterations 8 time step continuity errors : sum local = 1.77695e08, global = 1.40128e08, cumulative = 2.10184e05 DILUPBiCG: Solving for epsilon, Initial residual = 0.56183, Final residual = 5.35533e06, No Iterations 2 DILUPBiCG: Solving for k, Initial residual = 1, Final residual = 4.04759e06, No Iterations 19 ExecutionTime = 246.88 s ClockTime = 276 s Courant Number mean: 2.94236e06 max: 9.39065e05 Max Ur Courant Number = 0.000103406 Calculating averages Time = 0.792 DILUPBiCG: Solving for alpha, Initial residual = 2.07051e07, Final residual = 1.18426e16, No Iterations 1 Dispersed phase volume fraction = 0.349989 Min(alpha) = 2.24444e10 Max(alpha) = 1 DILUPBiCG: Solving for alpha, Initial residual = 4.87669e12, Final residual = 4.87669e12, No Iterations 0 Dispersed phase volume fraction = 0.349989 Min(alpha) = 2.24444e10 Max(alpha) = 1 GAMG: Solving for p, Initial residual = 0.99911, Final residual = 1.62335e09, No Iterations 16 time step continuity errors : sum local = 4.85304e07, global = 6.78739e08, cumulative = 2.09505e05 GAMG: Solving for p, Initial residual = 1.22245e07, Final residual = 4.05677e09, No Iterations 3 time step continuity errors : sum local = 4.3112e08, global = 2.02119e08, cumulative = 2.09707e05 DILUPBiCG: Solving for epsilon, Initial residual = 0.387714, Final residual = 9.80831e06, No Iterations 8 DILUPBiCG: Solving for k, Initial residual = 1, Final residual = 7.55652e06, No Iterations 9 ExecutionTime = 247.3 s ClockTime = 276 s Courant Number mean: 2.86588e06 max: 8.43784e05 Max Ur Courant Number = 8.57354e05 Calculating averages Time = 0.793 DILUPBiCG: Solving for alpha, Initial residual = 2.24368e07, Final residual = 1.04551e16, No Iterations 1 Dispersed phase volume fraction = 0.349989 Min(alpha) = 2.24425e10 Max(alpha) = 1 DILUPBiCG: Solving for alpha, Initial residual = 8.27431e12, Final residual = 8.27431e12, No Iterations 0 Dispersed phase volume fraction = 0.349989 Min(alpha) = 2.24425e10 Max(alpha) = 1 GAMG: Solving for p, Initial residual = 0.995351, Final residual = 3.11721e09, No Iterations 14 time step continuity errors : sum local = 3.67949e06, global = 1.30844e06, cumulative = 2.22792e05 GAMG: Solving for p, Initial residual = 2.60418e14, Final residual = 2.60418e14, No Iterations 0 time step continuity errors : sum local = 4.57825e06, global = 1.30906e06, cumulative = 2.35882e05 DILUPBiCG: Solving for epsilon, Initial residual = 0.872664, Final residual = 3.49504e06, No Iterations 11 DILUPBiCG: Solving for k, Initial residual = 1, Final residual = 6.70844e06, No Iterations 3 ExecutionTime = 247.69 s ClockTime = 277 s Courant Number mean: 7.98444e06 max: 0.000214576 Max Ur Courant Number = 0.000246573 Calculating averages Time = 0.794 DILUPBiCG: Solving for alpha, Initial residual = 5.0522e06, Final residual = 2.6061e15, No Iterations 1 Dispersed phase volume fraction = 0.349988 Min(alpha) = 2.24409e10 Max(alpha) = 1.00007 DILUPBiCG: Solving for alpha, Initial residual = 3.6218e10, Final residual = 2.19924e19, No Iterations 1 Dispersed phase volume fraction = 0.349988 Min(alpha) = 2.24409e10 Max(alpha) = 1.00007 GAMG: Solving for p, Initial residual = 0.99362, Final residual = 2.91436e09, No Iterations 19 time step continuity errors : sum local = 79.1722, global = 45.1975, cumulative = 45.1975 GAMG: Solving for p, Initial residual = 8.58661e06, Final residual = 8.05537e09, No Iterations 10 time step continuity errors : sum local = 0.0754832, global = 0.0614776, cumulative = 45.136 DILUPBiCG: Solving for epsilon, Initial residual = 0.333104, Final residual = 4.24405e06, No Iterations 285 DILUPBiCG: Solving for k, Initial residual = 0.98362, Final residual = 1.79691, No Iterations 1001 ExecutionTime = 250.35 s ClockTime = 279 s Courant Number mean: 2.9945 max: 496.215 Max Ur Courant Number = 712.315 Calculating averages Time = 0.795 DILUPBiCG: Solving for alpha, Initial residual = 0.305668, Final residual = 8.34833e11, No Iterations 40 Dispersed phase volume fraction = 0.308743 Min(alpha) = 10.9055 Max(alpha) = 19.6875 DILUPBiCG: Solving for alpha, Initial residual = 0.950365, Final residual = 6.24853e11, No Iterations 124 Dispersed phase volume fraction = 0.148458 Min(alpha) = 29.0766 Max(alpha) = 17.1806 Any help is appreciated. Thanks in advance. 

June 18, 2010, 04:00 

#2  
Senior Member
Gijsbert Wierink
Join Date: Mar 2009
Posts: 383
Rep Power: 10 
Hi Benjamin,
Sorry for this late reply, perhaps you have solved it already, but if not I'll try to help. I downloaded your case files, but can't find the actual mesh. Is it just a rectangular column? If so, blockMesh will work fine. Quote:
Have you tried to simply modify the bubbleCollumn tutorials for twoPhaseEulerFoam?
__________________
Regards, Gijs 

August 18, 2010, 12:41 
two Phase column simulation

#3 
New Member
Renato Soccol
Join Date: Aug 2010
Location: Blumenau, Brazil
Posts: 6
Rep Power: 8 
Benjamin,
I had the same problem then you, but my gasliquid system is little different, is a cylindrical column, this problem was solved. so...apply a relaxation factor to the firstly seconds in your simulation on the k and epsilon variable, about 0.9 for both, on the /system/fvsolution like this. sorry about my English. /** C++ **\  =========    \\ / F ield  OpenFOAM: The Open Source CFD Toolbox   \\ / O peration  Version: 1.6   \\ / A nd  Web: www.OpenFOAM.org   \\/ M anipulation   \**/ FoamFile { version 2.0; format ascii; class dictionary; location "system"; object fvSolution; } // * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * // solvers { p { solver GAMG; tolerance 1e08; relTol 0; smoother DIC; nPreSweeps 0; nPostSweeps 2; nFinestSweeps 2; cacheAgglomeration true; nCellsInCoarsestLevel 10; agglomerator faceAreaPair; mergeLevels 1; } Ua { solver PBiCG; preconditioner DILU; tolerance 1e05; relTol 0; } Ub { solver PBiCG; preconditioner DILU; tolerance 1e05; relTol 0; } alpha { solver PBiCG; preconditioner DILU; tolerance 1e10; relTol 0; } beta { solver PBiCG; preconditioner DILU; tolerance 1e10; relTol 0; } Theta { solver PBiCG; preconditioner DILU; tolerance 1e05; relTol 0; } k { solver PBiCG; preconditioner DILU; tolerance 1e05; relTol 0; } epsilon { solver PBiCG; preconditioner DILU; tolerance 1e05; relTol 0; } } PISO { nCorrectors 3; nNonOrthogonalCorrectors 0; nAlphaCorr 3; correctAlpha no; pRefCell 0; pRefValue 0; } relaxationFactors { Ua 1; Ub 1; alpha 1; beta 1; Theta 1; k 0.9; epsilon 0.9; } // ************************************************** *********************** // 

August 18, 2010, 12:53 
setFields

#4 
New Member
Renato Soccol
Join Date: Aug 2010
Location: Blumenau, Brazil
Posts: 6
Rep Power: 8 
their alpha initial conditions are correct. Alpha 0 means that there is water up to 450 and after that, alpha 1, only air is present on the column.


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