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May 1, 2012, 05:15 
Interfoam blows on parallel run

#1 
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Daniele Vicario
Join Date: Mar 2009
Location: Novara, Italy
Posts: 142
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Hi,
I've got an interfoam case that run well serially but blows almost immediately when run parallel (p_rgh residual became about 1e+47). Checkmesh reports: Code:
/**\  =========    \\ / F ield  OpenFOAM: The Open Source CFD Toolbox   \\ / O peration  Version: 2.1   \\ / A nd  Web: www.OpenFOAM.org   \\/ M anipulation   \**/ /* Windows 32 and 64 bit porting by blueCAPE: http://www.bluecape.com.pt *\  Based on Windows porting (2.0.x v4) by Symscape: http://www.symscape.com  \**/ Build : 2.1c62f134541ee Exec : checkmesh Date : May 01 2012 Time : 11:03:55 Host : "UFFTECNICO7" PID : 1220 Case : M:/f900layer 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 polyMesh for time = 0 Time = 0 Mesh stats points: 1540991 faces: 4219890 internal faces: 3997533 cells: 1356793 boundary patches: 5 point zones: 0 face zones: 0 cell zones: 0 Overall number of cells of each type: hexahedra: 1166345 prisms: 50764 wedges: 0 pyramids: 0 tet wedges: 1837 tetrahedra: 31 polyhedra: 137816 Checking topology... Boundary definition OK. Cell to face addressing OK. Point usage OK. Upper triangular ordering OK. Face vertices OK. Number of regions: 1 (OK). Checking patch topology for multiply connected surfaces ... Patch Faces Points Surface topology defaultFaces 0 0 ok (empty) walls 218118 251141 ok (nonclosed singly connected) outlet 2833 3848 ok (nonclosed singly connected) inletc 703 816 ok (nonclosed singly connected) inleth 703 816 ok (nonclosed singly connected) Checking geometry... Overall domain bounding box (0.0349486 0.0143717 0.27418) (0.215826 0.0145106 0.00527969) Mesh (nonempty, nonwedge) directions (1 1 1) Mesh (nonempty) directions (1 1 1) Boundary openness (1.383e016 8.59187e016 1.90504e016) OK. Max cell openness = 7.62663e016 OK. Max aspect ratio = 30.8252 OK. Minumum face area = 2.14489e009. Maximum face area = 3.0547e006. Face area magnitudes OK. Min volume = 4.266e013. Max volume = 3.09268e009. Total volume = 0.000168861. Cell volumes OK. Mesh nonorthogonality Max: 64.9781 average: 9.73097 Nonorthogonality check OK. Face pyramids OK. Max skewness = 2.08043 OK. Coupled point location match (average 0) OK. Mesh OK. End Enclosed you can find all my setup and boundary conditions. I tried to look in the forum but I wasn't able to find a clear reason with a serial run case has not to work in parallel. BTW, p_rgh residuals became huge in the very last GAMG calculation,just before the time step continuity errors print, no matter how many correctors I include. Why ? Thanks for any help.
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Daniele Vicario blueCFD2.1  Windows 7 

May 1, 2012, 11:11 

#2 
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Daniele Vicario
Join Date: Mar 2009
Location: Novara, Italy
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Just for reference I include the error interfoam returns:
Code:
M:\f900layer>mpiexec n 4 interfoam parallel /**\  =========    \\ / F ield  OpenFOAM: The Open Source CFD Toolbox   \\ / O peration  Version: 2.1   \\ / A nd  Web: www.OpenFOAM.org   \\/ M anipulation   \**/ /* Windows 32 and 64 bit porting by blueCAPE: http://www.bluecape.com.pt *\  Based on Windows porting (2.0.x v4) by Symscape: http://www.symscape.com  \**/ Build : 2.1c62f134541ee Exec : interfoam parallel Date : May 01 2012 Time : 17:00:37 Host : "UFFTECNICO7" PID : 9224 Case : M:/f900layer nProcs : 4 Slaves : 3 ( "UFFTECNICO7.9860" "UFFTECNICO7.8832" "UFFTECNICO7.9948" ) Pstream initialized with: floatTransfer : 0 nProcsSimpleSum : 0 commsType : nonBlocking 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 = 0 PIMPLE: Operating solver in PISO mode Reading field p_rgh Reading field alpha1 Reading field U Reading/calculating face flux field phi Reading transportProperties Selecting incompressible transport model Newtonian Selecting incompressible transport model Newtonian Selecting turbulence model type RASModel Selecting RAS turbulence model kOmegaSST kOmegaSSTCoeffs { alphaK1 0.85034; alphaK2 1; alphaOmega1 0.5; alphaOmega2 0.85616; gamma1 0.5532; gamma2 0.4403; beta1 0.075; beta2 0.0828; betaStar 0.09; a1 0.31; c1 10; } Reading g Calculating field g.h time step continuity errors : sum local = 0.00111869, global = 0.00111869, cumulative = 0.00111869 GAMG: Solving for pcorr, Initial residual = 1, Final residual = 0.0939645, No Iterations 12 GAMG: Solving for pcorr, Initial residual = 0.016886, Final residual = 0.000640254, No Iterations 2 GAMG: Solving for pcorr, Initial residual = 0.00475767, Final residual = 0.000198716, No Iterations 2 GAMG: Solving for pcorr, Initial residual = 0.00223692, Final residual = 8.4695e005, No Iterations 2 GAMG: Solving for pcorr, Initial residual = 0.00138859, Final residual = 4.343e005, No Iterations 2 time step continuity errors : sum local = 0.00013811, global = 6.02976e008, cumulative = 0.00111875 Courant Number mean: 0.960669 max: 211.701 Starting time loop Courant Number mean: 0.00226573 max: 0.499295 Interface Courant Number mean: 0 max: 0 deltaT = 2.35849e006 Time = 2.35849e006 MULES: Solving for alpha1 Phase1 volume fraction = 6.59604e007 Min(alpha1) = 0 Max(alpha1) = 1 MULES: Solving for alpha1 Phase1 volume fraction = 1.31921e006 Min(alpha1) = 0 Max(alpha1) = 1 MULES: Solving for alpha1 Phase1 volume fraction = 1.97881e006 Min(alpha1) = 3.65119e025 Max(alpha1) = 1 MULES: Solving for alpha1 Phase1 volume fraction = 2.63842e006 Min(alpha1) = 2.15788e023 Max(alpha1) = 1 smoothSolver: Solving for Ux, Initial residual = 1, Final residual = 0.000322717, No Iterations 2 smoothSolver: Solving for Uy, Initial residual = 1, Final residual = 0.000337929, No Iterations 2 smoothSolver: Solving for Uz, Initial residual = 1, Final residual = 0.0040445, No Iterations 1 GAMG: Solving for p_rgh, Initial residual = 1, Final residual = 0.068123, No Iterations 12 GAMG: Solving for p_rgh, Initial residual = 0.0173844, Final residual = 0.000657355, No Iterations 2 GAMG: Solving for p_rgh, Initial residual = 0.00486757, Final residual = 0.000201661, No Iterations 2 GAMG: Solving for p_rgh, Initial residual = 0.00227043, Final residual = 8.49585e005, No Iterations 2 GAMG: Solving for p_rgh, Initial residual = 0.00140338, Final residual = 4.25119e005, No Iterations 2 time step continuity errors : sum local = 3.06836e007, global = 1.29678e010, cumulative = 0.00111875 GAMG: Solving for p_rgh, Initial residual = 0.00129786, Final residual = 0.000116266, No Iterations 3 GAMG: Solving for p_rgh, Initial residual = 0.00122335, Final residual = 5.35063e005, No Iterations 2 GAMG: Solving for p_rgh, Initial residual = 0.000722669, Final residual = 2.37654e005, No Iterations 2 GAMG: Solving for p_rgh, Initial residual = 0.000567776, Final residual = 1.5856e005, No Iterations 2 GAMG: Solving for p_rgh, Initial residual = 0.000467471, Final residual = 1.23498e005, No Iterations 2 time step continuity errors : sum local = 8.71684e008, global = 1.61757e011, cumulative = 0.00111875 GAMG: Solving for p_rgh, Initial residual = 0.000415674, Final residual = 1.13259e005, No Iterations 2 GAMG: Solving for p_rgh, Initial residual = 0.000353334, Final residual = 9.06858e006, No Iterations 2 GAMG: Solving for p_rgh, Initial residual = 0.000310302, Final residual = 7.84026e006, No Iterations 2 GAMG: Solving for p_rgh, Initial residual = 0.000275727, Final residual = 6.77365e006, No Iterations 2 GAMG: Solving for p_rgh, Initial residual = 0.000249738, Final residual = 7.4289e008, No Iterations 9 time step continuity errors : sum local = 5.24309e010, global = 7.94578e013, cumulative = 0.00111875 smoothSolver: Solving for omega, Initial residual = 0.000751123, Final residual = 1.55042e007, No Iterations 3 smoothSolver: Solving for k, Initial residual = 1, Final residual = 6.12194e005, No Iterations 3 ExecutionTime = 83.218 s ClockTime = 83 s Courant Number mean: 0.00226108 max: 0.473956 Interface Courant Number mean: 2.85931e006 max: 0.177277 deltaT = 2.48788e006 Time = 4.84637e006 MULES: Solving for alpha1 Phase1 volume fraction = 3.33273e006 Min(alpha1) = 8.14863e023 Max(alpha1) = 1 MULES: Solving for alpha1 Phase1 volume fraction = 4.02704e006 Min(alpha1) = 1.06512e022 Max(alpha1) = 1 MULES: Solving for alpha1 Phase1 volume fraction = 4.72136e006 Min(alpha1) = 1.82129e022 Max(alpha1) = 1 MULES: Solving for alpha1 Phase1 volume fraction = 5.41567e006 Min(alpha1) = 3.46934e022 Max(alpha1) = 1 smoothSolver: Solving for Ux, Initial residual = 0.347181, Final residual = 0.00123868, No Iterations 1 smoothSolver: Solving for Uy, Initial residual = 0.288893, Final residual = 0.0020266, No Iterations 1 smoothSolver: Solving for Uz, Initial residual = 0.383562, Final residual = 0.00219642, No Iterations 1 GAMG: Solving for p_rgh, Initial residual = 0.0015376, Final residual = 0.000104287, No Iterations 9 GAMG: Solving for p_rgh, Initial residual = 0.419083, Final residual = 0.0417686, No Iterations 1 GAMG: Solving for p_rgh, Initial residual = 0.312039, Final residual = 0.0176243, No Iterations 3 GAMG: Solving for p_rgh, Initial residual = 0.0725684, Final residual = 0.00627527, No Iterations 2 GAMG: Solving for p_rgh, Initial residual = 0.0151413, Final residual = 0.001234, No Iterations 3 time step continuity errors : sum local = 9.63734e008, global = 6.82369e011, cumulative = 0.00111875 GAMG: Solving for p_rgh, Initial residual = 0.0484515, Final residual = 0.00417269, No Iterations 3 GAMG: Solving for p_rgh, Initial residual = 0.0624542, Final residual = 0.00412223, No Iterations 2 GAMG: Solving for p_rgh, Initial residual = 0.0105898, Final residual = 0.000706991, No Iterations 3 GAMG: Solving for p_rgh, Initial residual = 0.00328531, Final residual = 0.000314927, No Iterations 2 GAMG: Solving for p_rgh, Initial residual = 0.00140359, Final residual = 0.000102603, No Iterations 3 time step continuity errors : sum local = 3.09792e009, global = 2.40103e012, cumulative = 0.00111875 GAMG: Solving for p_rgh, Initial residual = 0.00327651, Final residual = 0.00030206, No Iterations 2 GAMG: Solving for p_rgh, Initial residual = 0.00127124, Final residual = 8.88962e005, No Iterations 2 GAMG: Solving for p_rgh, Initial residual = 0.000592684, Final residual = 3.52354e005, No Iterations 2 GAMG: Solving for p_rgh, Initial residual = 0.000374184, Final residual = 2.36845e005, No Iterations 2 GAMG: Solving for p_rgh, Initial residual = 0.000279674, Final residual = 8.80247e008, No Iterations 18 time step continuity errors : sum local = 2.69836e012, global = 3.12549e015, cumulative = 0.00111875 smoothSolver: Solving for omega, Initial residual = 0.000222471, Final residual = 6.54908e008, No Iterations 2 smoothSolver: Solving for k, Initial residual = 0.170403, Final residual = 4.19455e005, No Iterations 2 ExecutionTime = 133.469 s ClockTime = 134 s Courant Number mean: 0.00238928 max: 0.494389 Interface Courant Number mean: 3.02348e006 max: 0.198727 deltaT = 2.51301e006 Time = 7.35939e006 MULES: Solving for alpha1 Phase1 volume fraction = 6.11773e006 Min(alpha1) = 2.92291e022 Max(alpha1) = 1 MULES: Solving for alpha1 Phase1 volume fraction = 6.8198e006 Min(alpha1) = 5.42996e022 Max(alpha1) = 1 MULES: Solving for alpha1 Phase1 volume fraction = 7.52186e006 Min(alpha1) = 4.32711e022 Max(alpha1) = 1 MULES: Solving for alpha1 Phase1 volume fraction = 8.22393e006 Min(alpha1) = 5.48215e022 Max(alpha1) = 1 smoothSolver: Solving for Ux, Initial residual = 0.00159001, Final residual = 8.08127e006, No Iterations 1 smoothSolver: Solving for Uy, Initial residual = 0.00518775, Final residual = 2.83385e005, No Iterations 1 smoothSolver: Solving for Uz, Initial residual = 0.00147006, Final residual = 9.37366e006, No Iterations 1 GAMG: Solving for p_rgh, Initial residual = 0.209561, Final residual = 0.00619473, No Iterations 2 GAMG: Solving for p_rgh, Initial residual = 0.0441934, Final residual = 0.00174281, No Iterations 2 GAMG: Solving for p_rgh, Initial residual = 0.00981531, Final residual = 0.000424857, No Iterations 2 GAMG: Solving for p_rgh, Initial residual = 0.00334192, Final residual = 0.000247085, No Iterations 2 GAMG: Solving for p_rgh, Initial residual = 0.00158343, Final residual = 0.000131685, No Iterations 2 time step continuity errors : sum local = 1.96911e009, global = 5.51779e013, cumulative = 0.00111875 GAMG: Solving for p_rgh, Initial residual = 0.00272109, Final residual = 8.01031e005, No Iterations 2 GAMG: Solving for p_rgh, Initial residual = 0.00113411, Final residual = 4.98538e005, No Iterations 3 GAMG: Solving for p_rgh, Initial residual = 0.000662833, Final residual = 4.4928e005, No Iterations 3 GAMG: Solving for p_rgh, Initial residual = 0.000521569, Final residual = 5.21471e005, No Iterations 4 GAMG: Solving for p_rgh, Initial residual = 0.000461228, Final residual = 1.31055e+015, No Iterations 200 time step continuity errors : sum local = 1.96724e+010, global = 2.87158e+006, cumulative = 2.87158e+006 GAMG: Solving for p_rgh, Initial residual = 0.999957, Final residual = 0.0290708, No Iterations 2 GAMG: Solving for p_rgh, Initial residual = 0.0871181, Final residual = 0.00777385, No Iterations 1 GAMG: Solving for p_rgh, Initial residual = 0.0194607, Final residual = 0.000887361, No Iterations 2 GAMG: Solving for p_rgh, Initial residual = 0.0074301, Final residual = 0.000270396, No Iterations 2 GAMG: Solving for p_rgh, Initial residual = 0.00310641, Final residual = 9.25115e008, No Iterations 27 time step continuity errors : sum local = 1.23246e+007, global = 72576.5, cumulative = 2.799e+006 smoothSolver: Solving for omega, Initial residual = 1, Final residual = 0.000966837, No Iterations 4 smoothSolver: Solving for k, Initial residual = 0.994149, Final residual = 0.000994127, No Iterations 176 ExecutionTime = 271.695 s ClockTime = 272 s Courant Number mean: 5.34538e+013 max: 3.90337e+019 Interface Courant Number mean: 430.395 max: 2.22887e+008 deltaT = 3.21903e026 > FOAM Warning : From function Time::operator++() in file db/Time/Time.C at line 1010 Increased the timePrecision from 6 to 7 to distinguish between timeNames at time 7.35939e006 Time = 7.359389e006 > FOAM Warning : From function Time::operator++() in file db/Time/Time.C at line 1010 Increased the timePrecision from 7 to 8 to distinguish between timeNames at time 7.35939e006 job aborted: [ranks] message [0] process exited without calling finalize [13] terminated  error analysis  [0] on Ufftecnico7 interfoam ended prematurely and may have crashed. exit code 3  error analysis  Do you think could be a meshing problem ? Thanks for any help.
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Daniele Vicario blueCFD2.1  Windows 7 

May 1, 2012, 11:28 

#3 
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ms
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Hi. I have a similar issue and am exploring it at the moment. Current ideas include....
The pressure solver parameter, `nCellsInCoarsestLevel' is no longer appropriate with the reduced cell count in each domain. Smoothness across the entire domain is reduced during solution as each subdomain is considered in isolation of the others, other than information from the interfaces (ok, that sounds dodgy but it's the best I can do from memory). I'm paraphrasing but thought I'd try to contribute as I'm feeling depressed at the lack of feedback I'm getting on questions I've posted elsewhere. I'll see if I can find the articles I read and post them here... Good luck, I'll watch this thread.... Best regards, Mark. 

May 1, 2012, 11:40 

#4 
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Kyle Mooney
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While I didn't do a great job doing an apples to apples comparison, I've seen a few parallel interFoam cases in that blowup in 1.6ext but work fine in 2.1.x. It is worth noting that the compilation was done a little differently between the two foam versions: 1.6ext used mvapich2 and 2.1.x was done with openMPI. Could that be an issue? I'm not too familiar with subtleties of MPI implementations.
I was going to try and figure out what the issue is but I haven't had time to dig into it. 

May 2, 2012, 03:37 

#5 
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Anton Kidess
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Daniele, this simulation is broken from the start  the continuity is way off before the first pressure correction! To debug, I'd run just one time step, and then check the results to see what happens at the boundaries.
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May 2, 2012, 03:56 

#6 
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Alberto Passalacqua
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Hi,
your equation for the turbulent kinetic energy is not converging at all during the iterations. The code explodes when the equation for omega diverges. If your problem is significantly turbulent, you might want to solve k and omega at each timestep, by setting "turbOnFinalIterOnly no;" in the PIMPLE subdictionary, and eventually use PIMPLE instead of PISO, with underrelaxation (see below). Also, more in general:
Best,
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Alberto Passalacqua GeekoCFD  A free distribution based on openSUSE 64 bit with CFD tools, including OpenFOAM. Available as in both physical and virtual formats. OpenQBMM  An opensource implementation of quadraturebased moment methods. To obtain more accurate answers, please specify the version of OpenFOAM you are using. 

May 2, 2012, 06:03 

#7 
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Olivier
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hello,
Just to add my 2 cent ... try also to set maxCo at a lower value, 0.5 may be too high, try 0.2. regards, olivier 

May 2, 2012, 16:26 

#8 
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Daniele Vicario
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Thanks to all for so many suggestions. I'm going to try all of them.
Any idea why the sim runs serially without errors ?
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Daniele Vicario blueCFD2.1  Windows 7 

May 3, 2012, 00:59 

#9 
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Daniele Vicario
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@Alberto: I'll try to reduce the case dimension (110MB) in order to let you have it.
In the meanwhile I tried using reltol=0 but the solver crash at the first step: Code:
M:\f900layer>mpiexec n 4 interfoam parallel /**\  =========    \\ / F ield  OpenFOAM: The Open Source CFD Toolbox   \\ / O peration  Version: 2.1   \\ / A nd  Web: www.OpenFOAM.org   \\/ M anipulation   \**/ /* Windows 32 and 64 bit porting by blueCAPE: http://www.bluecape.com.pt *\  Based on Windows porting (2.0.x v4) by Symscape: http://www.symscape.com  \**/ Build : 2.1c62f134541ee Exec : interfoam parallel Date : May 03 2012 Time : 06:35:14 Host : "UFFTECNICO7" PID : 5656 Case : M:/f900layer nProcs : 4 Slaves : 3 ( "UFFTECNICO7.6140" "UFFTECNICO7.4864" "UFFTECNICO7.9408" ) Pstream initialized with: floatTransfer : 0 nProcsSimpleSum : 0 commsType : nonBlocking 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 = 0 PIMPLE: Operating solver in PISO mode Reading field p_rgh Reading field alpha1 Reading field U Reading/calculating face flux field phi Reading transportProperties Selecting incompressible transport model Newtonian Selecting incompressible transport model Newtonian Selecting turbulence model type RASModel Selecting RAS turbulence model kOmegaSST kOmegaSSTCoeffs { alphaK1 0.85034; alphaK2 1; alphaOmega1 0.5; alphaOmega2 0.85616; gamma1 0.5532; gamma2 0.4403; beta1 0.075; beta2 0.0828; betaStar 0.09; a1 0.31; c1 10; } Reading g Calculating field g.h time step continuity errors : sum local = 0.00111869, global = 0.00111869, cumulative = 0.00111869 GAMG: Solving for pcorr, Initial residual = 1, Final residual = 9.44929e009, No Iterations 100 GAMG: Solving for pcorr, Initial residual = 0.0168697, Final residual = 8.39749e009, No Iterations 37 time step continuity errors : sum local = 2.54022e008, global = 2.22964e010, cumulative = 0.00111869 Courant Number mean: 0.964422 max: 230.286 Starting time loop Courant Number mean: 0.00209202 max: 0.499536 Interface Courant Number mean: 0 max: 0 deltaT = 2.1692e006 Time = 2.1692e006 MULES: Solving for alpha1 Phase1 volume fraction = 6.06664e007 Min(alpha1) = 0 Max(alpha1) = 1 MULES: Solving for alpha1 Phase1 volume fraction = 1.21333e006 Min(alpha1) = 0 Max(alpha1) = 1 MULES: Solving for alpha1 Phase1 volume fraction = 1.81999e006 Min(alpha1) = 1.00739e024 Max(alpha1) = 1 MULES: Solving for alpha1 Phase1 volume fraction = 2.42666e006 Min(alpha1) = 1.41385e023 Max(alpha1) = 1 smoothSolver: Solving for Ux, Initial residual = 1, Final residual = 1.38163e012, No Iterations 6 smoothSolver: Solving for Uy, Initial residual = 1, Final residual = 1.37788e012, No Iterations 6 smoothSolver: Solving for Uz, Initial residual = 1, Final residual = 5.12925e011, No Iterations 5 GAMG: Solving for p_rgh, Initial residual = 1, Final residual = 5.24428e+006, No Iterations 200 GAMG: Solving for p_rgh, Initial residual = 0.793564, Final residual = 1.09358e+022, No Iterations 200 time step continuity errors : sum local = 2.17739e+023, global = 1.92673e+019, cumulative = 1.92673e+019 GAMG: Solving for p_rgh, Initial residual = 1, Final residual = 8.64916e009, No Iterations 46 GAMG: Solving for p_rgh, Initial residual = 0.0824733, Final residual = 9.41259e009, No Iterations 31 time step continuity errors : sum local = 4.78625e+031, global = 1.38544e+030, cumulative = 1.38544e+030 GAMG: Solving for p_rgh, Initial residual = 1, Final residual = 8.28675e009, No Iterations 48 GAMG: Solving for p_rgh, Initial residual = 0.0725632, Final residual = 7.96813e008, No Iterations 21 time step continuity errors : sum local = 4.52331e+070, global = 1.36619e+069, cumulative = 1.36619e+069 job aborted: [ranks] message [0] process exited without calling finalize [13] terminated  error analysis  [0] on Ufftecnico7 interfoam ended prematurely and may have crashed. exit code 3  error analysis  Using the PIMPLE subdict: Code:
PIMPLE { //pRefCell 0; //pRefValue 0; turbOnFinalIterOnly no; momentumPredictor yes; nCorrectors 3; nOuterCorrectors 2; nNonOrthogonalCorrectors 1; nAlphaCorr 1; nAlphaSubCycles 4; cAlpha 1; } Note: I haven't try yet to reduce the max Courant number. I also tried to check the decomposed BC and they are consistent with the full ones. I'm not an expert, at all, but the main thing, to me, is that the serial case is working and the parallel one no. Couldn't it be somehow linked to the processor BC, as anothr_acc suggested ? In the meanwhile I'm running the serial case with the new solution setup, just to see whether and when it's going to crash.
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Daniele Vicario blueCFD2.1  Windows 7 

May 4, 2012, 04:30 

#10 
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Daniele Vicario
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Just a small update.
It seems to be a meshing problem. I'm running the same geometry meshed without the layers refinement and it's parallel running with the original setup (all but the tollerances that have been corrected as Alberto suggested). I still have some questions:  Why didn't checkmesh return any errors (even when applied to each processorX case) ? Or, better, are you aware of any case that could bring checkmesh to say OK when actually it's not ?  Is it common for a critic mesh to be even more critic once decomposed ?Shouldn't decomposition be a... transparent operation ? Just a thought... browsing the forum I've got the impression that the big part of the problems are due to meshing. Rarely a fine tune of the solution dict can move a case from crash to good. From that point of view a good mesh is very good resistant to bad setup...at least from the solver stability point of view. The checklist of every beginner (like me) should be:  Mesh  Scheme  Solution Any comment ? Anyway I'll post any news on my current case.
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Daniele Vicario blueCFD2.1  Windows 7 

May 5, 2012, 02:42 

#11  
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Alberto Passalacqua
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Quote:
Quote:
P.S. What decomposition are you using? Scotch? Quote:
Best,
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Alberto Passalacqua GeekoCFD  A free distribution based on openSUSE 64 bit with CFD tools, including OpenFOAM. Available as in both physical and virtual formats. OpenQBMM  An opensource implementation of quadraturebased moment methods. To obtain more accurate answers, please specify the version of OpenFOAM you are using. 

May 5, 2012, 06:42 

#12 
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Daniele Vicario
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Thanks Alberto.
Yes, I'm using scotch. I'm a newbie and I'm working on a not so simple geometry, I don't think to be able to find a better decomposition than its . Now I'm working on the geometry, reducing the smaller (and hopefully negligibles) features. My goal is to obtain a good looking layers distribution on the mesh. At the moment I've got problems on sharp corners, I'll check on the SHM forum.
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Daniele Vicario blueCFD2.1  Windows 7 

May 6, 2012, 05:37 

#13 
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Daniele Vicario
Join Date: Mar 2009
Location: Novara, Italy
Posts: 142
Rep Power: 10 
Quick update:
Using DICGaussSeidel and DILUGaussSeidel as smoother for GAMG and smoothSolver solvers seems to solve the problem (just few time steps, so far). I'm just following Alberto's indirect help (http://www.cfdonline.com/Forums/ope...tml#post227426). Thanks.
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Daniele Vicario blueCFD2.1  Windows 7 

June 15, 2012, 06:14 

#14 
Member
ms
Join Date: Mar 2009
Location: West London
Posts: 45
Rep Power: 10 
Wow! These changes worked for me, too! I'm using simpleFoam with a Reynolds Stress turbulence model and like the case above, the solver seemed to run ok with a serial job but in parallel blew either after a long time for no clear reason, or blew on the first step.
Changing the smoother used with GAMG fixed the problem immediately. I've changed my relTols to zero (this did not cause the fix but I'm going with it anyway) and changed to the smooth solver for velocity, epsilon and R solution with the smoother specified above. Thanks so much for that tip. My jobs appear to be running now! Best regards, Mark. 

June 15, 2012, 06:48 

#15 
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ms
Join Date: Mar 2009
Location: West London
Posts: 45
Rep Power: 10 
Objectively, my pressure residuals dropped two orders of magnitude the moment I made this change. Happy days!


December 5, 2012, 09:52 

#16 
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Join Date: May 2012
Posts: 55
Rep Power: 8 
Dear Danvica,
could you post your fvsolutions file, please? I'm a bit confused, wheter you used GAMG as preconditioner or as solver. Thank you! 

December 22, 2012, 03:09 

#17 
Senior Member
Daniele Vicario
Join Date: Mar 2009
Location: Novara, Italy
Posts: 142
Rep Power: 10 
Hi styleworker,
I'm sorry but I cannot recover the right fsolution I used. Most probable: Code:
/** C++ **\  =========    \\ / F ield  OpenFOAM: The Open Source CFD Toolbox   \\ / O peration  Version: 2.0.0   \\ / A nd  Web: www.OpenFOAM.org   \\/ M anipulation   \**/ FoamFile { version 2.0; format ascii; class dictionary; location "system"; object fvSolution; } // * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * // solvers { pcorr // linear equation system solver for p { solver GAMG; // very efficient multigrid solver tolerance 1e07; // solver finishes if either absolute relTol 0; // tolerance is reached or the relative // tolerance here minIter 3; // a minimum number of iterations maxIter 200; // limitation of iterions number smoother GaussSeidel; // DIC  setting for GAMG nPreSweeps 1; // 1 for p, set to 0 for all other! nPostSweeps 2; // 2 is fine nFinestSweeps 2; // 2 is fine scaleCorrection true; // true is fine directSolveCoarsestLevel false; // false is fine cacheAgglomeration on; // on is fine; set to off, if dynamic // mesh refinement is used! nCellsInCoarsestLevel 500; // 500 is fine, // otherwise sqrt(number of cells) agglomerator faceAreaPair; // faceAreaPair is fine mergeLevels 1; // 1 is fine } p_rgh { solver GAMG; // very efficient multigrid solver tolerance 1e07; // solver finishes if either absolute relTol 0; // tolerance is reached or the relative // tolerance here minIter 3; // a minimum number of iterations maxIter 200; // limitation of iterions number smoother GaussSeidel; // DIC  setting for GAMG nPreSweeps 1; // 1 for p, set to 0 for all other! nPostSweeps 2; // 2 is fine nFinestSweeps 2; // 2 is fine scaleCorrection true; // true is fine directSolveCoarsestLevel false; // false is fine cacheAgglomeration on; // on is fine; set to off, if dynamic // mesh refinement is used! nCellsInCoarsestLevel 500; // 500 is fine, // otherwise sqrt(number of cells) agglomerator faceAreaPair; // faceAreaPair is fine mergeLevels 1; // 1 is fine } p_rghFinal { $p_rgh; tolerance 1e06; relTol 0; } U // linear equation system solver for U { solver smoothSolver; // solver type smoother GaussSeidel; // smoother type tolerance 1e07; // solver finishes if either absolute relTol 0; // tolerance is reached or the relative // tolerance here nSweeps 1; // setting for smoothSolver maxIter 200; // limitation of iterations number } UFinal // linear equation system solver for U { solver smoothSolver; // solver type smoother GaussSeidel; // smoother type tolerance 1e06; // solver finishes if either absolute relTol 0; // tolerance is reached or the relative // tolerance here nSweeps 1; // setting for smoothSolver maxIter 200; // limitation of iterations number } k { solver smoothSolver; smoother GaussSeidel; tolerance 1e7; relTol 0; nSweeps 1; } kFinal { solver smoothSolver; smoother GaussSeidel; tolerance 1e7; relTol 0; nSweeps 1; } omega { solver smoothSolver; smoother GaussSeidel; tolerance 1e7; relTol 0; nSweeps 1; } omegaFinal { solver smoothSolver; smoother GaussSeidel; tolerance 1e7; relTol 0; nSweeps 1; } } relaxationFactors { p 0.2; // 0.3 is stable, decrease for bad mesh U 0.6; // 0.7 is stable, decrease for bad mesh k 0.5; omega 0.5; } PIMPLE { //pRefCell 0; //pRefValue 0; turbOnFinalIterOnly yes; momentumPredictor yes; nCorrectors 3; nOuterCorrectors 2; nNonOrthogonalCorrectors 1; nAlphaCorr 1; nAlphaSubCycles 4; cAlpha 1; } // ************************************************************************* // Daniele
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Daniele Vicario blueCFD2.1  Windows 7 

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