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January 16, 2014, 14:47 
a problem with convergence in buoyantSimpleFoam

#1 
Member
Sergey
Join Date: Nov 2013
Posts: 87
Rep Power: 4 
Hello!
I'm trying to solve a problem of a flow through a complex geometry(picture is attached). I was able to mesh my stl geometry and set up the case in HelyxOS. However, when I am trying to solve it with buoyantSimpleFoam, there is no convergence: the residuals start oscillating. Probably it is because of complex geometry. I had the similar problem why I was trying to solve this case in abaqus and i hoped that OpenFOAM will be better, but got the same problem. log: Code:
case = /home/sergkuznet/Engys/HELYXOS/v2.0.0/UCfluidsmall_meshed_compressible log = /home/sergkuznet/Engys/HELYXOS/v2.0.0/UCfluidsmall_meshed_compressible/log/buoyantSimpleFoam.log solver = buoyantSimpleFoam vendorHome = /opt environmentLoader = /opt/openfoam222/etc/bashrc /**\  =========    \\ / F ield  OpenFOAM: The Open Source CFD Toolbox   \\ / O peration  Version: 2.2.2   \\ / A nd  Web: www.OpenFOAM.org   \\/ M anipulation   \**/ Build : 2.2.29240f8b967db Exec : buoyantSimpleFoam case /home/sergkuznet/Engys/HELYXOS/v2.0.0/UCfluidsmall_meshed_compressible Date : Jan 15 2014 Time : 23:30:58 Host : "ubuntu" PID : 24661 Case : /home/sergkuznet/Engys/HELYXOS/v2.0.0/UCfluidsmall_meshed_compressible 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 = 0 Reading g Reading thermophysical properties Selecting thermodynamics package { type heRhoThermo; mixture pureMixture; transport const; thermo hConst; equationOfState perfectGas; specie specie; energy sensibleEnthalpy; } Reading field U Reading/calculating face flux field phi Creating turbulence model Selecting RAS turbulence model kEpsilon kEpsilonCoeffs { label "Standard highRe k\u03B5"; fieldMaps { k kCompressible; epsilon epsilonCompressible; mut mut; alphat alphatCompressible; } Cmu 0.09; C1 1.44; C2 1.92; C3 0.85; alphah 1.111; alphak 1; alphaEps 0.76923; sigmak 1; sigmaEps 1.3; Prt 1; } Calculating field g.h Reading field p_rgh Creating fintite volume options from fvOptions Radiation model not active: radiationProperties not found Selecting radiationModel none SIMPLE: no convergence criteria found. Calculations will run for 50000 steps. Starting time loop Time = 1 smoothSolver: Solving for Ux, Initial residual = 1, Final residual = 0.05456998525, No Iterations 2 smoothSolver: Solving for Uy, Initial residual = 1, Final residual = 0.04761354967, No Iterations 2 smoothSolver: Solving for Uz, Initial residual = 1, Final residual = 0.0923876983, No Iterations 2 smoothSolver: Solving for h, Initial residual = 0.9999999996, Final residual = 0.02860158267, No Iterations 3 GAMG: Solving for p_rgh, Initial residual = 0.882758416, Final residual = 0.03173471025, No Iterations 4 time step continuity errors : sum local = 0.005249873879, global = 0.000182711125, cumulative = 0.000182711125 rho max/min : 1.158622649 1.142785577 smoothSolver: Solving for epsilon, Initial residual = 0.1608057626, Final residual = 0.006153099236, No Iterations 2 smoothSolver: Solving for k, Initial residual = 1, Final residual = 0.03719092912, No Iterations 3 ExecutionTime = 4.76 s ClockTime = 4 s Time = 2 smoothSolver: Solving for Ux, Initial residual = 0.7259532586, Final residual = 0.02361427294, No Iterations 3 smoothSolver: Solving for Uy, Initial residual = 0.7068399159, Final residual = 0.02238854075, No Iterations 3 smoothSolver: Solving for Uz, Initial residual = 0.6699165409, Final residual = 0.02056174524, No Iterations 3 smoothSolver: Solving for h, Initial residual = 0.7405307436, Final residual = 0.02051199796, No Iterations 3 GAMG: Solving for p_rgh, Initial residual = 0.304082482, Final residual = 0.01050962275, No Iterations 7 time step continuity errors : sum local = 0.1774290497, global = 0.001030155269, cumulative = 0.0008474441436 rho max/min : 1.158650312 1.13997601 smoothSolver: Solving for epsilon, Initial residual = 0.01048787725, Final residual = 0.000319066845, No Iterations 2 smoothSolver: Solving for k, Initial residual = 0.7883387769, Final residual = 0.04988614677, No Iterations 2 ExecutionTime = 7.4 s ClockTime = 7 s Time = 3 smoothSolver: Solving for Ux, Initial residual = 0.3011829881, Final residual = 0.00895536283, No Iterations 3 smoothSolver: Solving for Uy, Initial residual = 0.3393492916, Final residual = 0.03275950006, No Iterations 2 smoothSolver: Solving for Uz, Initial residual = 0.2385413804, Final residual = 0.007124100008, No Iterations 3 smoothSolver: Solving for h, Initial residual = 0.2914052321, Final residual = 0.01625010492, No Iterations 2 GAMG: Solving for p_rgh, Initial residual = 0.8042185927, Final residual = 0.02773146053, No Iterations 4 time step continuity errors : sum local = 0.1888755073, global = 0.006418408439, cumulative = 0.007265852582 rho max/min : 1.15968521 1.137278596 smoothSolver: Solving for epsilon, Initial residual = 0.01144151224, Final residual = 0.0003601066569, No Iterations 2 smoothSolver: Solving for k, Initial residual = 0.08325549938, Final residual = 0.00442307674, No Iterations 2 ExecutionTime = 9.86 s ClockTime = 9 s Time = 4 smoothSolver: Solving for Ux, Initial residual = 0.3572870107, Final residual = 0.01098460154, No Iterations 3 smoothSolver: Solving for Uy, Initial residual = 0.3412253921, Final residual = 0.01018265882, No Iterations 3 smoothSolver: Solving for Uz, Initial residual = 0.1938818624, Final residual = 0.00590410665, No Iterations 3 smoothSolver: Solving for h, Initial residual = 0.06609471347, Final residual = 0.004228284277, No Iterations 2 GAMG: Solving for p_rgh, Initial residual = 0.4711994431, Final residual = 0.02294413812, No Iterations 4 time step continuity errors : sum local = 0.2498850098, global = 0.00713703493, cumulative = 0.01440288751 rho max/min : 1.162113569 1.134617233 smoothSolver: Solving for epsilon, Initial residual = 0.01412601771, Final residual = 0.000576026232, No Iterations 2 smoothSolver: Solving for k, Initial residual = 0.05042717657, Final residual = 0.003666382958, No Iterations 2 ExecutionTime = 12.28 s ClockTime = 12 s Code:
Time = 6893 smoothSolver: Solving for Ux, Initial residual = 0.001109267103, Final residual = 9.301950987e05, No Iterations 2 smoothSolver: Solving for Uy, Initial residual = 0.002552499345, Final residual = 0.0002171982442, No Iterations 2 smoothSolver: Solving for Uz, Initial residual = 0.001721074846, Final residual = 0.0001393752654, No Iterations 2 smoothSolver: Solving for h, Initial residual = 0.001774111589, Final residual = 0.0001480908181, No Iterations 2 GAMG: Solving for p_rgh, Initial residual = 0.02942919705, Final residual = 0.001007022019, No Iterations 2 time step continuity errors : sum local = 0.006661556709, global = 1.051356534e05, cumulative = 0.0100249542 rho max/min : 1.555319782 1.028572963 smoothSolver: Solving for epsilon, Initial residual = 0.0006588752087, Final residual = 3.222172574e05, No Iterations 2 smoothSolver: Solving for k, Initial residual = 0.001165457605, Final residual = 7.263342197e05, No Iterations 2 ExecutionTime = 15783.15 s ClockTime = 15811 s Time = 6894 smoothSolver: Solving for Ux, Initial residual = 0.001105061853, Final residual = 9.282106832e05, No Iterations 2 smoothSolver: Solving for Uy, Initial residual = 0.002539850795, Final residual = 0.0002170841452, No Iterations 2 smoothSolver: Solving for Uz, Initial residual = 0.001712852001, Final residual = 0.0001392339211, No Iterations 2 smoothSolver: Solving for h, Initial residual = 0.001768589731, Final residual = 0.0001480461638, No Iterations 2 GAMG: Solving for p_rgh, Initial residual = 0.02919360825, Final residual = 0.0009926483288, No Iterations 2 time step continuity errors : sum local = 0.006562854633, global = 3.20007918e05, cumulative = 0.009992953411 rho max/min : 1.555999036 1.028541909 smoothSolver: Solving for epsilon, Initial residual = 0.0006562511602, Final residual = 3.206656798e05, No Iterations 2 smoothSolver: Solving for k, Initial residual = 0.001165405109, Final residual = 7.245995858e05, No Iterations 2 ExecutionTime = 15785.4 s ClockTime = 15814 s Time = 6895 smoothSolver: Solving for Ux, Initial residual = 0.00109332315, Final residual = 9.182453762e05, No Iterations 2 smoothSolver: Solving for Uy, Initial residual = 0.002532421163, Final residual = 0.0002170932441, No Iterations 2 smoothSolver: Solving for Uz, Initial residual = 0.001705007101, Final residual = 0.0001390125982, No Iterations 2 smoothSolver: Solving for h, Initial residual = 0.001764165224, Final residual = 0.0001480728942, No Iterations 2 GAMG: Solving for p_rgh, Initial residual = 0.0289295584, Final residual = 0.000999707326, No Iterations 2 time step continuity errors : sum local = 0.006605380848, global = 9.827082398e06, cumulative = 0.009983126328 rho max/min : 1.557878892 1.028510636 smoothSolver: Solving for epsilon, Initial residual = 0.0006530257994, Final residual = 3.188133514e05, No Iterations 2 smoothSolver: Solving for k, Initial residual = 0.001162685421, Final residual = 7.23104506e05, No Iterations 2 ExecutionTime = 15787.71 s ClockTime = 15816 s Code:
Time = 13613 smoothSolver: Solving for Ux, Initial residual = 0.0005045956734, Final residual = 4.340934053e05, No Iterations 2 smoothSolver: Solving for Uy, Initial residual = 0.001157194444, Final residual = 0.0001049946357, No Iterations 2 smoothSolver: Solving for Uz, Initial residual = 0.000840632502, Final residual = 7.075824151e05, No Iterations 2 smoothSolver: Solving for h, Initial residual = 0.0008323391129, Final residual = 7.193982016e05, No Iterations 2 GAMG: Solving for p_rgh, Initial residual = 0.01360653861, Final residual = 0.0004963259508, No Iterations 2 time step continuity errors : sum local = 0.003249437982, global = 3.573092127e05, cumulative = 0.01659601022 rho max/min : 1.620925196 1.026426236 smoothSolver: Solving for epsilon, Initial residual = 0.0003452632898, Final residual = 1.733068307e05, No Iterations 2 smoothSolver: Solving for k, Initial residual = 0.0005906923144, Final residual = 4.027091396e05, No Iterations 2 ExecutionTime = 31148.92 s ClockTime = 31204 s Time = 13614 smoothSolver: Solving for Ux, Initial residual = 0.000506167618, Final residual = 4.357008435e05, No Iterations 2 smoothSolver: Solving for Uy, Initial residual = 0.001159136638, Final residual = 0.0001051976481, No Iterations 2 smoothSolver: Solving for Uz, Initial residual = 0.0008379983297, Final residual = 7.044233602e05, No Iterations 2 smoothSolver: Solving for h, Initial residual = 0.0008271563341, Final residual = 7.156204547e05, No Iterations 2 GAMG: Solving for p_rgh, Initial residual = 0.01359108374, Final residual = 0.0004953122914, No Iterations 2 time step continuity errors : sum local = 0.003242773843, global = 3.226945802e05, cumulative = 0.01662827968 rho max/min : 1.621060156 1.026379888 smoothSolver: Solving for epsilon, Initial residual = 0.0003443170465, Final residual = 1.723312939e05, No Iterations 2 smoothSolver: Solving for k, Initial residual = 0.0005895732474, Final residual = 4.006604868e05, No Iterations 2 ExecutionTime = 31151.27 s ClockTime = 31206 s Code:
Time = 18885 smoothSolver: Solving for Ux, Initial residual = 0.0006130175635, Final residual = 4.984637275e05, No Iterations 2 smoothSolver: Solving for Uy, Initial residual = 0.00146555805, Final residual = 0.0001198237563, No Iterations 2 smoothSolver: Solving for Uz, Initial residual = 0.001049220622, Final residual = 8.563853344e05, No Iterations 2 smoothSolver: Solving for h, Initial residual = 0.001103103009, Final residual = 9.056864292e05, No Iterations 2 GAMG: Solving for p_rgh, Initial residual = 0.01792917561, Final residual = 0.0006453816647, No Iterations 2 time step continuity errors : sum local = 0.004211850033, global = 4.69373984e05, cumulative = 0.02838930114 rho max/min : 1.61685718 1.027702955 smoothSolver: Solving for epsilon, Initial residual = 0.0003757520635, Final residual = 1.640617344e05, No Iterations 2 smoothSolver: Solving for k, Initial residual = 0.0006832165346, Final residual = 4.135313509e05, No Iterations 2 ExecutionTime = 43243.93 s ClockTime = 43321 s Time = 18886 smoothSolver: Solving for Ux, Initial residual = 0.0006085962287, Final residual = 4.947465059e05, No Iterations 2 smoothSolver: Solving for Uy, Initial residual = 0.001453701216, Final residual = 0.0001189017535, No Iterations 2 smoothSolver: Solving for Uz, Initial residual = 0.001041301996, Final residual = 8.489900064e05, No Iterations 2 smoothSolver: Solving for h, Initial residual = 0.001102059566, Final residual = 9.050933718e05, No Iterations 2 GAMG: Solving for p_rgh, Initial residual = 0.01782668781, Final residual = 0.0006434618934, No Iterations 2 time step continuity errors : sum local = 0.004199870883, global = 1.300348859e05, cumulative = 0.02837629765 rho max/min : 1.61575725 1.027666084 smoothSolver: Solving for epsilon, Initial residual = 0.0003726036192, Final residual = 1.624410955e05, No Iterations 2 smoothSolver: Solving for k, Initial residual = 0.0006769270182, Final residual = 4.100176601e05, No Iterations 2 ExecutionTime = 43246.23 s ClockTime = 43324 s Time = 18887 smoothSolver: Solving for Ux, Initial residual = 0.0006047473189, Final residual = 4.917024084e05, No Iterations 2 smoothSolver: Solving for Uy, Initial residual = 0.001440066594, Final residual = 0.0001178240974, No Iterations 2 smoothSolver: Solving for Uz, Initial residual = 0.001033277701, Final residual = 8.422450783e05, No Iterations 2 smoothSolver: Solving for h, Initial residual = 0.001099930259, Final residual = 9.044716316e05, No Iterations 2 GAMG: Solving for p_rgh, Initial residual = 0.01778140607, Final residual = 0.0006504819822, No Iterations 2 time step continuity errors : sum local = 0.004246140865, global = 3.962517019e05, cumulative = 0.02841592282 rho max/min : 1.614670092 1.02762854 smoothSolver: Solving for epsilon, Initial residual = 0.000369558813, Final residual = 1.612523952e05, No Iterations 2 smoothSolver: Solving for k, Initial residual = 0.0006713037785, Final residual = 4.069978604e05, No Iterations 2 ExecutionTime = 43248.55 s ClockTime = 43326 s I wonder if some one can advise me how to tune the solver to get convergence? Thank you! 

January 18, 2014, 07:58 

#2 
Senior Member

hi skuznet,
Perhaps, with assuming your grid is fine enough, your boundary conditions for your turbulent model are not match with your case. they could affect the velocities strongly. I had same problem with my residuals, but for a simpler geometry, when I changed my turbulent BC my model solved. 

February 18, 2014, 17:42 

#3  
Member
Cong
Join Date: Nov 2012
Posts: 79
Rep Power: 5 
Quote:
How to solve it? I really appreciate your help. 

February 18, 2014, 18:14 

#4 
Member
Sergey
Join Date: Nov 2013
Posts: 87
Rep Power: 4 
Can you please give me an advise how do I choose turbulent BC to match model?
Or any reference please, Thanks! 

February 18, 2014, 23:05 

#5 
Senior Member

Dear Cong,
It depends on several parameters, your geometry, mesh, solvers, BCs, etc. Please post some additional information. Dear Sergey, Depending on your geometry and the the nature of flow, you should get some proper papers in the field you are working and surely they have some tips for you. also you can use this cfdonline tool: http://www.cfdonline.com/Tools/turbulence.php 

February 19, 2014, 05:30 

#6  
Member
Cong
Join Date: Nov 2012
Posts: 79
Rep Power: 5 
Quote:
thank you for your help. As a matter of fact, my first case is quite simple. A box with 6 isothermal walls, no inlet or outlet. I chose komega SST model and buoyantSimpleFoam. Mesh is refined closed to the wall and also layers are added. 

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