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March 6, 2016, 23:26 
Problem with chtMultiRegionSimpleFoam

#1 
Member
Ali
Join Date: Aug 2011
Location: Milwaukee
Posts: 34
Rep Power: 8 
Hello everyone,
This is my first time trying to model a multi region problem in OF. I'm trying to model the COMSOL's heat exchanger problem using OF. I did model the example in the Fluent and everything is working fine. Now I'm trying to run the same model in OF and I have problem with defining the boundary conditions. The energy equation explodes immediately and solver dumps the solution. I was wondering if anyone can take a look at my BC and trying to see if can help me find out what I am defining wrong. The link below is my case folder. https://drive.google.com/file/d/0B8L...ew?usp=sharing I would appreciate any helps/hints to solve this problem. Thank you in advance. Ali Last edited by alib022; March 22, 2016 at 12:17. 

March 22, 2016, 12:19 

#2 
Member
Ali
Join Date: Aug 2011
Location: Milwaukee
Posts: 34
Rep Power: 8 
Anyone?
Any help would be highly appreciated! 

March 23, 2016, 15:18 

#3 
Senior Member
Alex
Join Date: Oct 2013
Posts: 336
Rep Power: 14 
Hi Ali,
Take a look at the thread below if you really want to get some help. how to give enough info to get help Best regards, Alex
__________________
Web site where I present my Master's Thesis: foamingtime.wordpress.com The case I talk about in this site was solved with chtMultiRegionSimpleFoam solver and involves radiation. Some basic tutorials are also resolved step by step in the web. If you are interested in these matters, you are invited to come in! 

March 23, 2016, 22:57 

#4 
Member
Ali
Join Date: Aug 2011
Location: Milwaukee
Posts: 34
Rep Power: 8 
Alex,
Thank you for the guide, no wonder I didnt get anything! ok here is my mesh: m and here is the report of the checkMesh: Code:
/**\  =========    \\ / F ield  OpenFOAM: The Open Source CFD Toolbox   \\ / O peration  Version: 3.0.1   \\ / A nd  Web: www.OpenFOAM.org   \\/ M anipulation   \**/ Build : 3.0.1119cac7e8750 Exec : checkMesh Date : Mar 23 2016 Time : 20:54:34 Host : "aleLenovoZ4070" PID : 14145 Case : /home/ale/Desktop/he nProcs : 1 sigFpe : Enabling floating point exception trapping (FOAM_SIGFPE). fileModificationChecking : Monitoring runtime modified files using timeStampMaster allowSystemOperations : Allowing usersupplied system call operations // * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * // Create time Create polyMesh for time = 0 Time = 0 Mesh stats points: 839563 faces: 7787072 internal faces: 6833624 cells: 3655174 faces per cell: 4 boundary patches: 22 point zones: 0 face zones: 3 cell zones: 3 Overall number of cells of each type: hexahedra: 0 prisms: 0 wedges: 0 pyramids: 0 tet wedges: 0 tetrahedra: 3655174 polyhedra: 0 Checking topology... Boundary definition OK. Cell to face addressing OK. Point usage OK. Upper triangular ordering OK. Face vertices OK. *Number of regions: 3 The mesh has multiple regions which are not connected by any face. <<Writing region information to "0/cellToRegion" <<Writing region 0 with 1816924 cells to cellSet region0 <<Writing region 1 with 810203 cells to cellSet region1 <<Writing region 2 with 1028047 cells to cellSet region2 Checking patch topology for multiply connected surfaces... Patch Faces Points Surface topology wall_sheets:005 6074 3487 ok (nonclosed singly connected) wall_sheets:005shadow6074 3487 ok (nonclosed singly connected) symmet:004 4463 4097 ok (nonclosed singly connected) symmet:003 8541 5042 ok (nonclosed singly connected) inner_wall:002 8393 4365 ok (nonclosed singly connected) inner_wall:002shadow8393 4365 ok (nonclosed singly connected) inner_wall 18182 9483 ok (nonclosed singly connected) inner_wallshadow 18182 9483 ok (nonclosed singly connected) outer_wall 28716 14596 ok (nonclosed singly connected) inlet_air 149 97 ok (nonclosed singly connected) outlet_water 171 111 ok (nonclosed singly connected) inlet_water 164 106 ok (nonclosed singly connected) outlet_air 141 93 ok (nonclosed singly connected) symmet 13073 7501 ok (nonclosed singly connected) wall_buffers 14915 9184 ok (nonclosed singly connected) wall_buffersshadow 14915 9184 ok (nonclosed singly connected) wall_sheets 5326 3292 ok (nonclosed singly connected) wall_sheetsshadow 5326 3292 ok (nonclosed singly connected) wall_outsideubes 230714 118113 ok (nonclosed singly connected) wall_outsideubesshadow230714 118113 ok (nonclosed singly connected) wall_insidetubes 165411 83728 ok (nonclosed singly connected) wall_insidetubesshadow165411 83728 ok (nonclosed singly connected) Checking geometry... Overall domain bounding box (375 130 105) (375 130 4.039243e08) Mesh has 3 geometric (nonempty/wedge) directions (1 1 1) Mesh has 3 solution (nonempty) directions (1 1 1) Boundary openness (6.910344e20 1.516309e17 1.878536e16) OK. Max cell openness = 2.891113e16 OK. Max aspect ratio = 5.910575 OK. Minimum face area = 0.2897532. Maximum face area = 88.66169. Face area magnitudes OK. Min volume = 0.09708428. Max volume = 245.6505. Total volume = 1.155842e+07. Cell volumes OK. Mesh nonorthogonality Max: 60.60822 average: 18.27468 Nonorthogonality check OK. Face pyramids OK. Max skewness = 0.6922095 OK. Coupled point location match (average 0) OK. Mesh OK. End I have to mention that I have multiple coupled patches. About the fvsolution I'm using identical solvers for air and water as below: Code:
solvers { p_rgh { solver GAMG; tolerance 1e7; relTol 0.01; smoother DIC; cacheAgglomeration true; nCellsInCoarsestLevel 10; agglomerator faceAreaPair; mergeLevels 1; maxIter 100; } "(Uhekepsilon)" { solver PBiCG; preconditioner DILU; tolerance 1e6; relTol 0.1; // solver smoothSolver; // smoother symGaussSeidel; // tolerance 1e7; // relTol 0.01; } } Code:
solvers { h { solver PCG; preconditioner DIC; tolerance 1e06; relTol 0.1; } } I suspect my boundary condition and played with that a lot but didnt have any success and my solution divergences in the very first iteration Code:
Create time Create fluid mesh for region air_domain for time = 0 Create fluid mesh for region water_domain for time = 0 Create solid mesh for region solid_domain for time = 0 *** Reading fluid mesh thermophysical properties for region air_domain Adding to thermoFluid Selecting thermodynamics package { type heRhoThermo; mixture pureMixture; transport polynomial; thermo hPolynomial; equationOfState icoPolynomial; specie specie; energy sensibleEnthalpy; } Adding to rhoFluid Adding to UFluid Adding to phiFluid Adding to gFluid Adding to hRefFluid Adding to ghFluid Adding to ghfFluid Adding to turbulence Selecting turbulence model type RAS Selecting RAS turbulence model kEpsilon kEpsilonCoeffs { Cmu 0.09; C1 1.44; C2 1.92; C3 0.33; sigmak 1; sigmaEps 1.3; } Radiation model not active: radiationProperties not found Selecting radiationModel none Adding MRF No MRF models present Adding fvOptions No finite volume options present *** Reading fluid mesh thermophysical properties for region water_domain Adding to thermoFluid Selecting thermodynamics package { type heRhoThermo; mixture pureMixture; transport const; thermo hConst; equationOfState perfectFluid; specie specie; energy sensibleInternalEnergy; } Adding to rhoFluid Adding to UFluid Adding to phiFluid Adding to gFluid Adding to hRefFluid Adding to ghFluid Adding to ghfFluid Adding to turbulence Selecting turbulence model type laminar Radiation model not active: radiationProperties not found Selecting radiationModel none Adding MRF No MRF models present Adding fvOptions No finite volume options present *** Reading solid mesh thermophysical properties for region solid_domain Adding to thermos Selecting thermodynamics package { type heSolidThermo; mixture pureMixture; transport constIso; thermo hConst; equationOfState rhoConst; specie specie; energy sensibleEnthalpy; } Adding to radiations Radiation model not active: radiationProperties not found Selecting radiationModel none Adding fvOptions No finite volume options present Time = 1 Solving for fluid region air_domain DILUPBiCG: Solving for Ux, Initial residual = 1, Final residual = 0.05257607, No Iterations 2 DILUPBiCG: Solving for Uy, Initial residual = 1, Final residual = 0.04018972, No Iterations 3 DILUPBiCG: Solving for Uz, Initial residual = 1, Final residual = 0.05142399, No Iterations 2 DILUPBiCG: Solving for h, Initial residual = 1, Final residual = 0.08905775, No Iterations 2 Min/max T:293.15 300.0003 GAMG: Solving for p_rgh, Initial residual = 1, Final residual = 0.008710555, No Iterations 8 GAMG: Solving for p_rgh, Initial residual = 0.08695835, Final residual = 0.0001994177, No Iterations 2 GAMG: Solving for p_rgh, Initial residual = 0.009356995, Final residual = 2.857887e05, No Iterations 2 GAMG: Solving for p_rgh, Initial residual = 0.001269825, Final residual = 1.161426e05, No Iterations 2 GAMG: Solving for p_rgh, Initial residual = 0.0003067193, Final residual = 1.221515e06, No Iterations 3 GAMG: Solving for p_rgh, Initial residual = 8.127729e05, Final residual = 5.682916e07, No Iterations 2 time step continuity errors : sum local = 0.001377804, global = 3.193082e05, cumulative = 3.193082e05 Min/max rho:1.170812 1.199585 DILUPBiCG: Solving for epsilon, Initial residual = 0.2477916, Final residual = 0.02169919, No Iterations 2 bounding epsilon, min: 0.1537348 max: 74.9272 average: 9.377313 DILUPBiCG: Solving for k, Initial residual = 1, Final residual = 0.07581812, No Iterations 3 Solving for fluid region water_domain DILUPBiCG: Solving for Ux, Initial residual = 1, Final residual = 0.02036105, No Iterations 17 DILUPBiCG: Solving for Uy, Initial residual = 1, Final residual = 0.06697598, No Iterations 13 DILUPBiCG: Solving for Uz, Initial residual = 1, Final residual = 0.06763109, No Iterations 11 DILUPBiCG: Solving for e, Initial residual = 1, Final residual = 0.05426087, No Iterations 16 Min/max T:299.9414 353.15 GAMG: Solving for p_rgh, Initial residual = 1, Final residual = 0.008721249, No Iterations 14 GAMG: Solving for p_rgh, Initial residual = 0.8852784, Final residual = 0.003070489, No Iterations 2 GAMG: Solving for p_rgh, Initial residual = 0.05862079, Final residual = 0.0004594317, No Iterations 2 GAMG: Solving for p_rgh, Initial residual = 0.008742093, Final residual = 8.090802e05, No Iterations 23 GAMG: Solving for p_rgh, Initial residual = 0.01612499, Final residual = 6.594953e05, No Iterations 3 GAMG: Solving for p_rgh, Initial residual = 0.003798012, Final residual = 3.770664e05, No Iterations 2 time step continuity errors : sum local = 0.003390077, global = 0.0003362716, cumulative = 0.0003043408 Min/max rho:2 2 Solving for solid region solid_domain DICPCG: Solving for h, Initial residual = 0.9999927, Final residual = 0.08746619, No Iterations 3 DICPCG: Solving for h, Initial residual = 0.1366519, Final residual = 0.007957356, No Iterations 3 DICPCG: Solving for h, Initial residual = 0.06695286, Final residual = 0.003200763, No Iterations 3 DICPCG: Solving for h, Initial residual = 0.04195219, Final residual = 0.00191589, No Iterations 3 DICPCG: Solving for h, Initial residual = 0.029766, Final residual = 0.002800009, No Iterations 2 DICPCG: Solving for h, Initial residual = 0.02267911, Final residual = 0.001069138, No Iterations 3 Min/max T:300 300.0004 ExecutionTime = 104.02 s ClockTime = 104 s Time = 2 Solving for fluid region air_domain DILUPBiCG: Solving for Ux, Initial residual = 0.9242532, Final residual = 0.03203833, No Iterations 4 DILUPBiCG: Solving for Uy, Initial residual = 0.9410005, Final residual = 0.03857488, No Iterations 4 DILUPBiCG: Solving for Uz, Initial residual = 0.9284244, Final residual = 0.05554513, No Iterations 4 DILUPBiCG: Solving for h, Initial residual = 0.9218401, Final residual = 0.08333141, No Iterations 3 Min/max T:203.8075 498.9083 GAMG: Solving for p_rgh, Initial residual = 0.4579909, Final residual = 0.002487677, No Iterations 5 Any help will be highly appreciated. Thanks again Ali 

March 30, 2016, 12:17 

#5 
Member
Ali
Join Date: Aug 2011
Location: Milwaukee
Posts: 34
Rep Power: 8 
Alex,
Any suggestions? 

April 4, 2016, 12:03 

#6 
Member
Ali
Join Date: Aug 2011
Location: Milwaukee
Posts: 34
Rep Power: 8 
Hello everyone again,
Ok I haven't receive any hint from here but I'll keep updating maybe someone can eventually help me. I did a lot of throuble shooting with my model and turns out my initial boundary condition werent completely right. Now, I'm facing another problem which I am not sure what is causing this problem. The problem is, in my air domain, there is one voxel that blows up and the rest are fine as you can see in the image. And also the air doesn't get to the end of the domain and just stuck near close the inlet. Any suggestions? 

June 16, 2016, 01:46 

#7 
Senior Member
Nima Samkhaniani
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Location: Tehran, Iran
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would you please share the fvSchemes
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June 17, 2016, 10:05 

#8 
Member
Ali
Join Date: Aug 2011
Location: Milwaukee
Posts: 34
Rep Power: 8 
Hi Nima,
Thanks for the response. Here are my fvSchemes files for Air Domain: Code:
/** C++ **\  =========    \\ / F ield  OpenFOAM: The Open Source CFD Toolbox   \\ / O peration  Version: 3.0.1   \\ / A nd  Web: www.OpenFOAM.org   \\/ M anipulation   \**/ FoamFile { version 2.0; format ascii; class dictionary; object fvSchemes; } // * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * // ddtSchemes { default steadyState; } gradSchemes { default Gauss linear; } divSchemes { default none; div(phi,U) bounded Gauss upwind; div(phi,K) bounded Gauss upwind; div(phi,e) bounded Gauss upwind; div(phi,Ekp) bounded Gauss upwind; div(phi,h) bounded Gauss upwind; div(phi,k) bounded Gauss upwind; div(phi,epsilon) bounded Gauss upwind; div(phi,omega) bounded Gauss upwind; div(phi,R) bounded Gauss upwind; div(R) bounded Gauss upwind; div(((rho*nuEff)*dev2(T(grad(U))))) Gauss linear; } laplacianSchemes { default Gauss linear corrected; } interpolationSchemes { default linear; } snGradSchemes { default corrected; } // ************************************************************************* // Code:
/** C++ **\  =========    \\ / F ield  OpenFOAM: The Open Source CFD Toolbox   \\ / O peration  Version: 3.0.1   \\ / A nd  Web: www.OpenFOAM.org   \\/ M anipulation   \**/ FoamFile { version 2.0; format ascii; class dictionary; location "system/solid_domain"; object fvSchemes; } // * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * // ddtSchemes { default steadyState; } gradSchemes { default Gauss linear; } divSchemes { default none; } laplacianScsteadyStatehemes { default none; laplacian(alpha,h) Gauss linear uncorrected; } laplacianSchemes { default Gauss linear corrected; } interpolationSchemes { default linear; } snGradSchemes { default uncorrected; } // ************************************************************************* // Code:
/** C++ **\  =========    \\ / F ield  OpenFOAM: The Open Source CFD Toolbox   \\ / O peration  Version: 3.0.1   \\ / A nd  Web: www.OpenFOAM.org   \\/ M anipulation   \**/ FoamFile { version 2.0; format ascii; class dictionary; object fvSchemes; } // * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * // ddtSchemes { default steadyState; } gradSchemes { default Gauss linear; } divSchemes { default none; div(phi,U) bounded Gauss upwind; div(phi,K) bounded Gauss upwind; div(phi,h) bounded Gauss upwind; div(phi,e) bounded Gauss upwind; div(phi,Ekp) bounded Gauss upwind; div(phi,k) bounded Gauss upwind; div(phi,omega) bounded Gauss upwind; div(phi,epsilon) bounded Gauss upwind; div(phi,R) bounded Gauss upwind; div(R) bounded Gauss linear; div(((rho*nuEff)*dev2(T(grad(U))))) Gauss linear; } laplacianSchemes { default Gauss linear corrected; } interpolationSchemes { default linear; } snGradSchemes { default corrected; } // ************************************************************************* // 

June 18, 2016, 01:58 

#9 
Senior Member
Nima Samkhaniani
Join Date: Sep 2009
Location: Tehran, Iran
Posts: 1,231
Blog Entries: 1
Rep Power: 18 
1 change air fvScheme as:
Code:
gradSchemes { default cellLimited Gauss linear 0.5; }
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Telegram channel (https://telegram.me/openfoam4Iranian) My Weblog in Persian(http://openfoam.blogfa.com/) My Personal Website (http://nimasamkhaniani.ir/) 

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