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same geometry,structured and unstructured mesh,different behaviour. 

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December 1, 2012, 04:01 
same geometry,structured and unstructured mesh,different behaviour.

#1 
Senior Member
Dongyue Li
Join Date: Jun 2012
Location: Torino, Italy
Posts: 756
Rep Power: 10 
Hi Foamers:
I use the same geometry but different mesh which one is structured and the other is unstructured simulating bubblecolumn via twoPhaseEulerFoam, the other things such as BCs,FVscheme is totally the same. while running, the deltaT is getting smaller and smaller in unstructured mesh,but delta T is stable in structured mesh. I check the unstructured mesh is OK, and the quality is above 0.36. can anybody explain this to me? thanks in advance. Code:
// * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * // Create time Create mesh for time = 0 Reading g Reading transportProperties Calculating face flux field phi1 Calculating face flux field phi2 Reading field alpha1 Reading field p Reading field k Reading field epsilon Calculating field nut2 Calculating field nuEff1 Calculating field nuEff2 Calculating field DDtU1 and DDtU2 Calculating field g.h Selecting dragModel for phase 1: SchillerNaumann Selecting dragModel for phase 2: SchillerNaumann dragPhase is 1 Selecting viscosityModel Syamlal Selecting conductivityModel HrenyaSinclair Selecting radialModel SinclairJackson Selecting granularPressureModel Lun Selecting frictionalStressModel JohnsonJackson Courant Number mean: 1.38889e06 max: 0.0114746 PIMPLE: Operating solver in PISO mode Starting time loop Courant Number mean: 1.37514e06 max: 0.011361 Max Ur Courant Number = 0.011361 deltaT = 0.00235294 Time = 0.00235294 MULES: Solving for alpha1 MULES: Solving for alpha1 Dispersed phase volume fraction = 0.400913 Min(alpha1) = 0 Max(alpha1) = 1 GAMG: Solving for p, Initial residual = 1, Final residual = 0.0863091, No Iterations 4 time step continuity errors : sum local = 1.06044e05, global = 1.14961e06, cumulative = 1.14961e06 GAMG: Solving for p, Initial residual = 0.000385431, Final residual = 4.25161e09, No Iterations 8 time step continuity errors : sum local = 2.34062e08, global = 8.86366e09, cumulative = 1.15847e06 ExecutionTime = 1.83 s ClockTime = 2 s Courant Number mean: 0.000961133 max: 0.281556 Max Ur Courant Number = 0.284771 deltaT = 0.0027451 Time = 0.00509804 MULES: Solving for alpha1 MULES: Solving for alpha1 Dispersed phase volume fraction = 0.400913 Min(alpha1) = 1.12164e20 Max(alpha1) = 1 GAMG: Solving for p, Initial residual = 8.63083e05, Final residual = 4.00274e06, No Iterations 1 time step continuity errors : sum local = 2.73396e05, global = 2.22315e06, cumulative = 1.06468e06 GAMG: Solving for p, Initial residual = 4.42412e05, Final residual = 5.60681e09, No Iterations 7 time step continuity errors : sum local = 4.22789e08, global = 6.16051e10, cumulative = 1.06529e06 ExecutionTime = 3.15 s ClockTime = 3 s Courant Number mean: 0.0017551 max: 0.699786 Max Ur Courant Number = 0.556128 deltaT = 0.00194902 Time = 0.00704706 MULES: Solving for alpha1 MULES: Solving for alpha1 Dispersed phase volume fraction = 0.400913 Min(alpha1) = 6.81353e17 Max(alpha1) = 1 GAMG: Solving for p, Initial residual = 3.65894e05, Final residual = 1.57627e06, No Iterations 1 time step continuity errors : sum local = 5.16964e06, global = 9.58478e08, cumulative = 9.69446e07 GAMG: Solving for p, Initial residual = 5.6711e05, Final residual = 6.50899e09, No Iterations 6 time step continuity errors : sum local = 2.37495e08, global = 3.80727e09, cumulative = 9.65639e07 ExecutionTime = 4.44 s ClockTime = 5 s Courant Number mean: 0.00167936 max: 1.02324 Max Ur Courant Number = 0.747501 deltaT = 1.99755e06 Time = 0.00949938 MULES: Solving for alpha1 MULES: Solving for alpha1 Dispersed phase volume fraction = 0.400913 Min(alpha1) = 8.90338e22 Max(alpha1) = 1 GAMG: Solving for p, Initial residual = 0.0481777, Final residual = 0.00240455, No Iterations 1 time step continuity errors : sum local = 7.55737e07, global = 8.0092e10, cumulative = 8.87419e07 GAMG: Solving for p, Initial residual = 0.170165, Final residual = 5.99529e09, No Iterations 14 time step continuity errors : sum local = 2.58254e12, global = 1.71226e13, cumulative = 8.87418e07 ExecutionTime = 25.1 s ClockTime = 25 s Courant Number mean: 0.000246545 max: 0.954781 Max Ur Courant Number = 0.715363 deltaT = 1.04607e06 Time = 0.00950043 MULES: Solving for alpha1 MULES: Solving for alpha1 Dispersed phase volume fraction = 0.400913 Min(alpha1) = 8.90337e22 Max(alpha1) = 1 GAMG: Solving for p, Initial residual = 0.0453175, Final residual = 0.00277426, No Iterations 1 time step continuity errors : sum local = 8.16799e07, global = 3.74529e10, cumulative = 8.87044e07 GAMG: Solving for p, Initial residual = 0.112757, Final residual = 4.36559e09, No Iterations 14 time step continuity errors : sum local = 1.57546e12, global = 1.38487e13, cumulative = 8.87044e07 ExecutionTime = 26.55 s ClockTime = 27 s Courant Number mean: 0.000191191 max: 0.775023 Max Ur Courant Number = 0.526832 deltaT = 6.74865e07 Time = 0.0095011 MULES: Solving for alpha1 MULES: Solving for alpha1 Dispersed phase volume fraction = 0.400913 Min(alpha1) = 8.90337e22 Max(alpha1) = 1 GAMG: Solving for p, Initial residual = 0.0344062, Final residual = 0.00217738, No Iterations 1 time step continuity errors : sum local = 7.2002e07, global = 5.49242e10, cumulative = 8.86494e07 GAMG: Solving for p, Initial residual = 0.0678397, Final residual = 7.71205e09, No Iterations 13 time step continuity errors : sum local = 2.89794e12, global = 2.90138e13, cumulative = 8.86494e07 ExecutionTime = 28.17 s ClockTime = 28 s Courant Number mean: 0.000169 max: 0.691341 Max Ur Courant Number = 0.421516 deltaT = 4.88083e07 Time = 0.00950159 MULES: Solving for alpha1 MULES: Solving for alpha1 Dispersed phase volume fraction = 0.400913 Min(alpha1) = 8.90337e22 Max(alpha1) = 1 GAMG: Solving for p, Initial residual = 0.0242849, Final residual = 0.00133999, No Iterations 1 time step continuity errors : sum local = 5.12642e07, global = 7.3266e10, cumulative = 8.85762e07 GAMG: Solving for p, Initial residual = 0.0466661, Final residual = 6.45613e09, No Iterations 13 time step continuity errors : sum local = 2.72667e12, global = 2.42677e13, cumulative = 8.85761e07 ExecutionTime = 29.69 s ClockTime = 30 s Courant Number mean: 0.00016667 max: 0.681466 Max Ur Courant Number = 0.389559 deltaT = 3.58113e07 Time = 0.00950195 MULES: Solving for alpha1 MULES: Solving for alpha1 Dispersed phase volume fraction = 0.400913 Min(alpha1) = 8.90337e22 Max(alpha1) = 1 GAMG: Solving for p, Initial residual = 0.0275894, Final residual = 0.00152494, No Iterations 1 time step continuity errors : sum local = 6.50407e07, global = 7.86185e10, cumulative = 8.84975e07 GAMG: Solving for p, Initial residual = 0.048091, Final residual = 7.15538e09, No Iterations 13 time step continuity errors : sum local = 3.39665e12, global = 3.10169e13, cumulative = 8.84975e07 ExecutionTime = 31.21 s ClockTime = 32 s Courant Number mean: 0.000177114 max: 0.742118 Max Ur Courant Number = 0.434414 deltaT = 2.41277e07 Time = 0.00950219 MULES: Solving for alpha1 MULES: Solving for alpha1 Dispersed phase volume fraction = 0.400913 Min(alpha1) = 8.90336e22 Max(alpha1) = 1 GAMG: Solving for p, Initial residual = 0.0434491, Final residual = 0.00265364, No Iterations 1 time step continuity errors : sum local = 1.17267e06, global = 7.89578e10, cumulative = 8.84185e07 GAMG: Solving for p, Initial residual = 0.0916966, Final residual = 4.20824e09, No Iterations 14 time step continuity errors : sum local = 2.22575e12, global = 2.16475e13, cumulative = 8.84185e07 ExecutionTime = 32.73 s ClockTime = 33 s Courant Number mean: 0.000201607 max: 0.927977 Max Ur Courant Number = 0.614956 deltaT = 1.30002e07 Time = 0.00950232 MULES: Solving for alpha1 MULES: Solving for alpha1 Dispersed phase volume fraction = 0.400913 Min(alpha1) = 8.90336e22 Max(alpha1) = 1 GAMG: Solving for p, Initial residual = 0.0523101, Final residual = 0.00307465, No Iterations 1 time step continuity errors : sum local = 1.1458e06, global = 7.83281e10, cumulative = 8.83402e07 GAMG: Solving for p, Initial residual = 0.167959, Final residual = 6.72381e09, No Iterations 14 time step continuity errors : sum local = 3.37666e12, global = 1.97947e13, cumulative = 8.83402e07 ExecutionTime = 34.2 s ClockTime = 34 s Courant Number mean: 0.000213776 max: 1.09291 Max Ur Courant Number = 0.801885 deltaT = 5.94748e08 Time = 0.00950238 MULES: Solving for alpha1 MULES: Solving for alpha1 Dispersed phase volume fraction = 0.400913 Min(alpha1) = 8.90336e22 Max(alpha1) = 1 GAMG: Solving for p, Initial residual = 0.0529512, Final residual = 0.00271119, No Iterations 1 time step continuity errors : sum local = 7.97202e07, global = 7.88211e10, cumulative = 8.82613e07 GAMG: Solving for p, Initial residual = 0.213293, Final residual = 8.38933e09, No Iterations 14 time step continuity errors : sum local = 3.56226e12, global = 1.41309e13, cumulative = 8.82613e07 ExecutionTime = 35.67 s ClockTime = 36 s Courant Number mean: 0.000203657 max: 1.09677 Max Ur Courant Number = 0.834422 deltaT = 2.71137e08 Time = 0.0095024 MULES: Solving for alpha1 MULES: Solving for alpha1 Dispersed phase volume fraction = 0.400913 Min(alpha1) = 8.90336e22 Max(alpha1) = 1 GAMG: Solving for p, Initial residual = 0.0456457, Final residual = 0.00239763, No Iterations 1 time step continuity errors : sum local = 6.07151e07, global = 6.76636e10, cumulative = 8.81937e07 GAMG: Solving for p, Initial residual = 0.170025, Final residual = 7.23531e09, No Iterations 14 time step continuity errors : sum local = 2.45147e12, global = 1.08e13, cumulative = 8.81936e07 ExecutionTime = 37.23 s ClockTime = 38 s Courant Number mean: 0.000167332 max: 0.906812 Max Ur Courant Number = 0.660191 deltaT = 1.495e08 Time = 0.00950242 MULES: Solving for alpha1 MULES: Solving for alpha1 Dispersed phase volume fraction = 0.400913 Min(alpha1) = 8.90336e22 Max(alpha1) = 1 GAMG: Solving for p, Initial residual = 0.0400672, Final residual = 0.00243865, No Iterations 1 time step continuity errors : sum local = 6.57129e07, global = 5.7262e10, cumulative = 8.81364e07 GAMG: Solving for p, Initial residual = 0.109301, Final residual = 4.88328e09, No Iterations 14 time step continuity errors : sum local = 1.58805e12, global = 1.09765e13, cumulative = 8.81364e07 ExecutionTime = 38.74 s ClockTime = 39 s Courant Number mean: 0.000143578 max: 0.769801 Max Ur Courant Number = 0.514251 deltaT = 9.7103e09 Time = 0.00950243 > FOAM Warning : From function Time::operator++() in file db/Time/Time.C at line 1024 Increased the timePrecision from 6 to 7 to distinguish between timeNames at time 0.00950242 MULES: Solving for alpha1 MULES: Solving for alpha1 Dispersed phase volume fraction = 0.400913 Min(alpha1) = 8.90336e22 Max(alpha1) = 1 GAMG: Solving for p, Initial residual = 0.0301994, Final residual = 0.00188676, No Iterations 1 time step continuity errors : sum local = 5.87628e07, global = 4.48811e10, cumulative = 8.80915e07 GAMG: Solving for p, Initial residual = 0.0676315, Final residual = 8.08041e09, No Iterations 13 time step continuity errors : sum local = 2.84689e12, global = 3.41917e13, cumulative = 8.80915e07 ExecutionTime = 40.17 s ClockTime = 40 s Courant Number mean: 0.000133312 max: 0.69952 Max Ur Courant Number = 0.425703 deltaT = 6.94069e09 Time = 0.009502436 Last edited by sharonyue; December 1, 2012 at 04:48. 

December 1, 2012, 12:10 

#2 
New Member
Jie (Jay) Zhang
Join Date: Sep 2010
Location: FL, U.S.
Posts: 27
Rep Power: 9 
Usually, unstructured mesh is worse than structured mesh. There is a thread talking about the difference between unstructured mesh and structured mesh
http://www.cfdonline.com/Forums/cfx...uredmesh.html And the mesh quality depends on the meshing tool. Since you used auto adjusted delta T, when delta T getting smaller, it means the solution of flow has a trend to blow up. So I suggest using structured mesh if you can generate it. Jie 

December 1, 2012, 20:30 

#3  
Senior Member
Dongyue Li
Join Date: Jun 2012
Location: Torino, Italy
Posts: 756
Rep Power: 10 
Quote:


December 2, 2012, 14:09 

#4  
New Member
Jie (Jay) Zhang
Join Date: Sep 2010
Location: FL, U.S.
Posts: 27
Rep Power: 9 
Quote:
To prevent blowing up, I would suggest you generally since I don't know detail about the solver you are using: 1. Reduce relaxation parameter. 2. Use upwind scheme instead of central scheme; 3. Use scheme with lowerorder accuracy; 4. Reduce the tolerance in FvSolution (The time spent on each iteration will be longer); 5. Use a better initial condition, such as the solution from run on structured mesh; 6. Try another meshing tool to generate unstructured mesh (Gmesh is disappointing on generating 3D Mesh); 7. Try another solver is there are other alternatives. Jie 

December 2, 2012, 15:10 

#5 
Member
Arnout
Join Date: Nov 2010
Posts: 36
Rep Power: 9 
Instead of moving mesh, you can define a source term with the average impuls of the stirror and apply it on the stirrer volume. The hex mesh should be possible.


December 4, 2012, 23:56 

#6  
Senior Member
Dongyue Li
Join Date: Jun 2012
Location: Torino, Italy
Posts: 756
Rep Power: 10 
Quote:
in structured mesh. I got this result, that looks normal. in unstructured mesh, in the fvscheme which is used in structured mesh, the delta T is getting too small, so I change the div(phi1,alpha1) Gauss limitedLinearV 1; div(phi2,alpha1) Gauss limitedLinearV 1; to div(phi,alpha1) Gauss upwind; div(phir,alpha1) Gauss upwind; just as expected, the solution didnot blow up. but the result is unrealistic: I have alse tried reduce relaxation parameter and reduce the tolerance, but that did not have an impact to the unrealistic behaviour. anyway, you are exactly correct about the modifying the fvscheme to prevent blowing up in an unstructured mesh, but how to handle this unrealistic behaviour? now I have to use unstructured mesh, because I dont know how to set the structured mesh's inner face in ICEM. http://www.cfdonline.com/Forums/ope...tml#post395366 

December 5, 2012, 16:32 

#7 
New Member
Jie (Jay) Zhang
Join Date: Sep 2010
Location: FL, U.S.
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Rep Power: 9 
If you start a run on unstructured mesh with a solution from structured mesh as initial condition, what's going to happen? Will it converge to a unrealistic solution or not?


December 5, 2012, 21:05 

#8  
Senior Member
Dongyue Li
Join Date: Jun 2012
Location: Torino, Italy
Posts: 756
Rep Power: 10 
Quote:
do you mean this? anyway, thanks for your sustained help. 

December 6, 2012, 11:18 

#9 
New Member
Jie (Jay) Zhang
Join Date: Sep 2010
Location: FL, U.S.
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You can use the openFoam utility: mapFields to map the solution from the structured mesh to unstructured mesh.


December 7, 2012, 00:06 

#10 
Senior Member
Dongyue Li
Join Date: Jun 2012
Location: Torino, Italy
Posts: 756
Rep Power: 10 
I tryed mapfields,
Code:
patchMap ( INLET INLET ); patchMap ( OUTLET OUTLET ); patchMap ( WALLS WALLS ); cuttingPatches ( ); Code:
/**\  =========    \\ / F ield  OpenFOAM: The Open Source CFD Toolbox   \\ / O peration  Version: 2.1.x   \\ / A nd  Web: www.OpenFOAM.org   \\/ M anipulation   \**/ Build : 2.1.x6f9e6e8dbbf5 Exec : twoPhaseEulerFoam Date : Dec 07 2012 Time : 12:01:59 Host : "cfd" PID : 2770 Case : /home/cfd/OpenFOAM/tutorials/multiphase/twoPhaseEulerFoam/column/bubblecoloum2 nProcs : 1 sigFpe : Enabling floating point exception trapping (FOAM_SIGFPE). fileModificationChecking : Monitoring runtime modified files using timeStampMaster allowSystemOperations : Disallowing usersupplied system call operations // * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * // Create time Create mesh for time = 3.3 Reading g Reading transportProperties Calculating face flux field phi1 Calculating face flux field phi2 Reading field alpha1 Reading field p Reading field k Reading field epsilon Calculating field nut2 Calculating field nuEff1 Calculating field nuEff2 Calculating field DDtU1 and DDtU2 Calculating field g.h Selecting dragModel for phase 1: SchillerNaumann Selecting dragModel for phase 2: SchillerNaumann dragPhase is 1 Selecting viscosityModel Syamlal Selecting conductivityModel HrenyaSinclair Selecting radialModel SinclairJackson Selecting granularPressureModel Lun Selecting frictionalStressModel JohnsonJackson Courant Number mean: 0.0352143 max: 0.72803 PIMPLE: Operating solver in PISO mode Starting time loop Courant Number mean: 0.0241194 max: 0.498651 Max Ur Courant Number = 0.383116 deltaT = 0.00136986 Time = 3.30137 MULES: Solving for alpha1 MULES: Solving for alpha1 Dispersed phase volume fraction = 0.299165 Min(alpha1) = 2.15895e13 Max(alpha1) = 1.09964 GAMG: Solving for p, Initial residual = 0.00656045, Final residual = 0.000298759, No Iterations 1 time step continuity errors : sum local = 0.000400447, global = 3.45188e06, cumulative = 3.45188e06 GAMG: Solving for p, Initial residual = 0.000641632, Final residual = 5.89681e09, No Iterations 17 time step continuity errors : sum local = 7.9181e09, global = 6.00606e09, cumulative = 3.44587e06 ExecutionTime = 5.96 s ClockTime = 6 s Courant Number mean: 0.0248958 max: 0.585803 Max Ur Courant Number = 0.697338 deltaT = 0.000976536 Time = 3.30235 MULES: Solving for alpha1 MULES: Solving for alpha1 Dispersed phase volume fraction = 0.299163 Min(alpha1) = 2.2483e13 Max(alpha1) = 1.08973 GAMG: Solving for p, Initial residual = 0.00439207, Final residual = 0.000287956, No Iterations 1 time step continuity errors : sum local = 0.000169108, global = 4.09768e07, cumulative = 3.85564e06 GAMG: Solving for p, Initial residual = 0.00109433, Final residual = 6.41174e09, No Iterations 19 time step continuity errors : sum local = 3.74784e09, global = 2.38899e09, cumulative = 3.85325e06 ExecutionTime = 9.81 s ClockTime = 10 s Courant Number mean: 0.0195134 max: 0.993167 Max Ur Courant Number = 1.04815 deltaT = 0.000465017 Time = 3.30281 MULES: Solving for alpha1 MULES: Solving for alpha1 Dispersed phase volume fraction = 0.299163 Min(alpha1) = 2.28675e13 Max(alpha1) = 1.08657 GAMG: Solving for p, Initial residual = 0.0110043, Final residual = 0.000779613, No Iterations 1 time step continuity errors : sum local = 0.000114244, global = 6.50821e07, cumulative = 4.50407e06 GAMG: Solving for p, Initial residual = 0.00298644, Final residual = 8.64015e09, No Iterations 15 time step continuity errors : sum local = 1.27991e09, global = 9.74229e10, cumulative = 4.5031e06 ExecutionTime = 13.46 s ClockTime = 13 s Courant Number mean: 0.0107308 max: 1.58822 Max Ur Courant Number = 1.44814 deltaT = 0.000146368 Time = 3.30296 MULES: Solving for alpha1 MULES: Solving for alpha1 Dispersed phase volume fraction = 0.299163 Min(alpha1) = 2.28675e13 Max(alpha1) = 1.08562 GAMG: Solving for p, Initial residual = 0.0363906, Final residual = 0.00252655, No Iterations 1 time step continuity errors : sum local = 8.60275e05, global = 1.47109e06, cumulative = 5.97418e06 GAMG: Solving for p, Initial residual = 0.00697779, Final residual = 5.53144e09, No Iterations 12 time step continuity errors : sum local = 1.94042e10, global = 1.15085e11, cumulative = 5.9742e06 ExecutionTime = 16.94 s ClockTime = 17 s Courant Number mean: 0.00443779 max: 0.981418 Max Ur Courant Number = 0.957677 deltaT = 7.45332e05 Time = 3.30303 MULES: Solving for alpha1 MULES: Solving for alpha1 Dispersed phase volume fraction = 0.299163 Min(alpha1) = 2.28675e13 Max(alpha1) = 1.08493 GAMG: Solving for p, Initial residual = 0.194527, Final residual = 0.011994, No Iterations 1 time step continuity errors : sum local = 7.45561e05, global = 3.19653e07, cumulative = 6.29385e06 GAMG: Solving for p, Initial residual = 0.0342165, Final residual = 6.34788e09, No Iterations 14 time step continuity errors : sum local = 4.53813e11, global = 2.84153e11, cumulative = 6.29388e06 ExecutionTime = 20.5 s ClockTime = 20 s Courant Number mean: 0.00321038 max: 1.91241 Max Ur Courant Number = 1.8986 deltaT = 1.94832e05 Time = 3.30305 MULES: Solving for alpha1 MULES: Solving for alpha1 Dispersed phase volume fraction = 0.299163 Min(alpha1) = 2.28675e13 Max(alpha1) = 1.0848 GAMG: Solving for p, Initial residual = 0.66717, Final residual = 0.040409, No Iterations 1 time step continuity errors : sum local = 4.30358e05, global = 2.37226e07, cumulative = 6.05665e06 GAMG: Solving for p, Initial residual = 0.0749171, Final residual = 8.60659e09, No Iterations 16 time step continuity errors : sum local = 1.46005e11, global = 6.53075e12, cumulative = 6.05666e06 ExecutionTime = 24.22 s ClockTime = 24 s Courant Number mean: 0.00125969 max: 1.00435 Max Ur Courant Number = 1.00264 deltaT = 9.6987e06 Time = 3.30306 MULES: Solving for alpha1 > FOAM Warning : From function Time::operator++() in file db/Time/Time.C at line 1024 Increased the timePrecision from 6 to 7 to distinguish between timeNames at time 3.30306 MULES: Solving for alpha1 Dispersed phase volume fraction = 0.299163 Min(alpha1) = 2.28675e13 Max(alpha1) = 1.08472 GAMG: Solving for p, Initial residual = 0.810231, Final residual = 0.0626473, No Iterations 1 time step continuity errors : sum local = 5.39472e05, global = 2.64604e07, cumulative = 6.32126e06 GAMG: Solving for p, Initial residual = 0.0977699, Final residual = 5.21597e09, No Iterations 17 time step continuity errors : sum local = 7.02455e12, global = 3.95107e12, cumulative = 6.32126e06 ExecutionTime = 28.02 s ClockTime = 28 s Courant Number mean: 0.00109578 max: 2.10824 Max Ur Courant Number = 1.4274 deltaT = 2.30017e06 Time = 3.303064 MULES: Solving for alpha1 MULES: Solving for alpha1 Dispersed phase volume fraction = 0.299163 Min(alpha1) = 2.28675e13 Max(alpha1) = 1.0847 GAMG: Solving for p, Initial residual = 0.929304, Final residual = 0.0625062, No Iterations 1 time step continuity errors : sum local = 2.41344e05, global = 4.81651e08, cumulative = 6.2731e06 GAMG: Solving for p, Initial residual = 0.10263, Final residual = 5.41482e09, No Iterations 18 time step continuity errors : sum local = 3.66151e12, global = 2.58953e12, cumulative = 6.2731e06 ExecutionTime = 31.8 s ClockTime = 32 s Courant Number mean: 0.000505613 max: 0.757155 Max Ur Courant Number = 0.751618 deltaT = 1.51895e06 Time = 3.303065 MULES: Solving for alpha1 > FOAM Warning : From function Time::operator++() in file db/Time/Time.C at line 1024 Increased the timePrecision from 7 to 8 to distinguish between timeNames at time 3.30307 MULES: Solving for alpha1 Dispersed phase volume fraction = 0.299163 Min(alpha1) = 2.28675e13 Max(alpha1) = 1.0847 GAMG: Solving for p, Initial residual = 0.812829, Final residual = 0.0712496, No Iterations 1 time step continuity errors : sum local = 3.64446e05, global = 5.60153e08, cumulative = 6.32912e06 GAMG: Solving for p, Initial residual = 0.105448, Final residual = 6.24808e09, No Iterations 18 time step continuity errors : sum local = 4.86702e12, global = 2.5297e12, cumulative = 6.32912e06 ExecutionTime = 35.67 s ClockTime = 36 s Courant Number mean: 0.000617812 max: 1.15822 Max Ur Courant Number = 0.973487 deltaT = 6.55726e07 Time = 3.303066 MULES: Solving for alpha1 MULES: Solving for alpha1 Dispersed phase volume fraction = 0.299163 Min(alpha1) = 2.28675e13 Max(alpha1) = 1.08469 GAMG: Solving for p, Initial residual = 0.912736, Final residual = 0.0717027, No Iterations 1 time step continuity errors : sum local = 3.39342e05, global = 5.31678e08, cumulative = 6.27595e06 GAMG: Solving for p, Initial residual = 0.103759, Final residual = 8.11996e09, No Iterations 16 time step continuity errors : sum local = 6.37729e12, global = 3.39787e12, cumulative = 6.27596e06 ExecutionTime = 39.34 s ClockTime = 39 s Courant Number mean: 0.000524284 max: 1.3323 Max Ur Courant Number = 1.30873 deltaT = 2.46087e07 Time = 3.3030662 MULES: Solving for alpha1 MULES: Solving for alpha1 Dispersed phase volume fraction = 0.299163 Min(alpha1) = 2.28675e13 Max(alpha1) = 1.08468 GAMG: Solving for p, Initial residual = 0.900043, Final residual = 0.0595418, No Iterations 1 time step continuity errors : sum local = 2.60454e05, global = 1.05431e07, cumulative = 6.38139e06 GAMG: Solving for p, Initial residual = 0.108187, Final residual = 7.39797e09, No Iterations 17 time step continuity errors : sum local = 5.83461e12, global = 2.75699e12, cumulative = 6.38139e06 ExecutionTime = 43.06 s ClockTime = 43 s Courant Number mean: 0.000461765 max: 1.72491 Max Ur Courant Number = 1.71906 deltaT = 7.13334e08 Time = 3.3030663 MULES: Solving for alpha1 > FOAM Warning : From function Time::operator++() in file db/Time/Time.C at line 1024 Increased the timePrecision from 8 to 9 to distinguish between timeNames at time 3.30307 1‘ Code:
ddtSchemes { default Euler; } gradSchemes { default Gauss linear; } divSchemes { default none; div(phi1,U1) Gauss upwind; div(phi2,U2) Gauss upwind; div(phi2,k) Gauss upwind; div(phi2,epsilon) Gauss upwind; div(phi,alpha1) Gauss upwind; div(phir,alpha1) Gauss limitedLinear01 1; div(phi,Theta) Gauss upwind; div(Rc1) Gauss linear; div(Rc2) Gauss linear; } laplacianSchemes { default none; laplacian(nuEff1,U1) Gauss linear corrected; laplacian(nuEff2,U2) Gauss linear corrected; laplacian(Dp,p) Gauss linear corrected; laplacian(alpha1PpMag,alpha1) Gauss linear corrected; laplacian((alpha1k*nuEff2),k) Gauss linear corrected; laplacian((alpha1Eps*nuEff2),epsilon) Gauss linear corrected; } interpolationSchemes { default linear; } snGradSchemes { default corrected; } fluxRequired { default no; p ; } Code:
ddtSchemes { default Euler; } gradSchemes { default Gauss linear; } divSchemes { default none; div(phi1,U1) Gauss limitedLinearV 1; div(phi2,U2) Gauss limitedLinearV 1; div(phi2,k) Gauss limitedLinear 1; div(phi2,epsilon) Gauss limitedLinear 1; div(phi,alpha1) Gauss limitedLinear01 1; div(phir,alpha1) Gauss limitedLinear01 1; div(phi,Theta) Gauss limitedLinear 1; div(Rc1) Gauss linear; div(Rc2) Gauss linear; } laplacianSchemes { default none; laplacian(nuEff1,U1) Gauss linear corrected; laplacian(nuEff2,U2) Gauss linear corrected; laplacian(Dp,p) Gauss linear corrected; laplacian(alpha1PpMag,alpha1) Gauss linear corrected; laplacian((alpha1k*nuEff2),k) Gauss linear corrected; laplacian((alpha1Eps*nuEff2),epsilon) Gauss linear corrected; } interpolationSchemes { default linear; } snGradSchemes { default corrected; } fluxRequired { default no; p ; } I am not sure this bubblefoam can work on an unstructured mesh. 

December 12, 2012, 02:32 

#11 
Senior Member
Dongyue Li
Join Date: Jun 2012
Location: Torino, Italy
Posts: 756
Rep Power: 10 
is there anyone doing the similar simulation？


December 20, 2012, 12:07 

#12 
Senior Member
Dongyue Li
Join Date: Jun 2012
Location: Torino, Italy
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I am waiting for any suggestion...


January 2, 2013, 23:38 

#13 
Member
Jianye Xia
Join Date: Mar 2009
Posts: 32
Rep Power: 10 
I want to simulate the same problem like you, but I am not quite sure about the boundary conditions for each variable, how did you set in your test case? Is boundary conditions have strong effects on the results?


January 2, 2013, 23:40 

#14  
Senior Member
Dongyue Li
Join Date: Jun 2012
Location: Torino, Italy
Posts: 756
Rep Power: 10 
Quote:


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