# Temperature in simpleFoam takes lots of Iterations

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 June 5, 2012, 11:13 Temperature in simpleFoam takes lots of Iterations #1 New Member   Join Date: Oct 2011 Posts: 19 Rep Power: 6 Hey Guys, i added temperature to simpleFoam as described in this Tutorial for icoFoam. Everything works fine, though the Solution needs a lot of Time since the Solving for T needs about 500 Iterations, which themselves require noticeable more time than the other variables. I've waited nearly a day and it doesn't get better. Is is a large Mesh so i it would be great if anyone had any experience in whether this is preventable or maybe necessary? The entry in fvSolution is: T { solver BICCG; preconditioner DILU; tolerance 1e-7; relTol 0; }; The entries in fvSchemes are: divSchemes { div(phi,T) Gauss upwind; } laplacianSchemes { default Gauss linear corrected; } Here an extract of the log-File: DILUPBiCG: Solving for Ux, Initial residual = 0.00100392, Final residual = 1.55987e-06, No Iterations 3 DILUPBiCG: Solving for Uy, Initial residual = 0.000223085, Final residual = 1.98551e-06, No Iterations 2 DILUPBiCG: Solving for Uz, Initial residual = 0.00409009, Final residual = 2.67272e-06, No Iterations 4 DICPCG: Solving for p, Initial residual = 0.0102603, Final residual = 0.000508878, No Iterations 10 time step continuity errors : sum local = 0.00022309, global = -3.75985e-05, cumulative = -0.0631543 DILUPBiCG: Solving for omega, Initial residual = 1.34598e-05, Final residual = 1.55138e-06, No Iterations 1 bounding omega, min: -55157.8 max: 7.30739e+06 average: 74327.1 DILUPBiCG: Solving for k, Initial residual = 0.00209203, Final residual = 3.94547e-06, No Iterations 3 bounding k, min: -0.000121144 max: 1.54218 average: 0.0210219 DILUPBiCG: Solving for T, Initial residual = 0.000117996, Final residual = 9.23239e-08, No Iterations 527 ExecutionTime = 80799 s ClockTime = 80875 s This is my first question in this Forum, so i hope everything is fine, thanks for answers!

 June 6, 2012, 03:12 #2 Senior Member   Christian Lucas Join Date: Aug 2009 Location: Braunschweig, Germany Posts: 200 Rep Power: 10 Hi, set "relTol" to "0.1" Best Regards, Christian

 June 6, 2012, 05:09 #3 New Member   Join Date: Oct 2011 Posts: 19 Rep Power: 6 Thank you Chris, now it does about 300 Iterations which is already much better!

October 19, 2012, 00:42
Same problem with p
#4
Member

Suranga Dharmarathne
Join Date: Jan 2011
Location: TX, USA
Posts: 39
Rep Power: 7
Quote:
 Originally Posted by Chris Lucas Hi, set "relTol" to "0.1" Best Regards, Christian
DILUPBiCG: Solving for Ux, Initial residual = 0.239894, Final residual = 0.0179294, No Iterations 1
DILUPBiCG: Solving for Uy, Initial residual = 0.179769, Final residual = 0.0125606, No Iterations 1
DILUPBiCG: Solving for Uz, Initial residual = 0.641576, Final residual = 0.0401016, No Iterations 1
DICPCG: Solving for p, Initial residual = 0.0565956, Final residual = 0.00545759, No Iterations 679
time step continuity errors : sum local = 10.8709, global = 0.0357859, cumulative = 1.01927
DILUPBiCG: Solving for epsilon, Initial residual = 0.100542, Final residual = 0.00703845, No Iterations 1
DILUPBiCG: Solving for k, Initial residual = 0.200465, Final residual = 0.0159354, No Iterations 1
ExecutionTime = 246.64 s ClockTime = 250 s

Please let me know how cope up with this.

 October 19, 2012, 00:50 #5 Member   Meindert de Groot Join Date: Jun 2012 Location: Netherlands Posts: 34 Rep Power: 6 Try using a multi-grid (GAMG) solver for the pressure equation, and have a look at the motorBike tutorial to get an impression on how to use it.

 October 19, 2012, 01:35 #6 Member   Suranga Dharmarathne Join Date: Jan 2011 Location: TX, USA Posts: 39 Rep Power: 7 Meindert, Thank you for quick reply I'll try this.

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