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-   -   overshooting of Omega in SST komega using simpleFoam (http://www.cfd-online.com/Forums/openfoam/91928-overshooting-omega-sst-komega-using-simplefoam.html)

cm_jubayer August 26, 2011 11:54

overshooting of Omega in SST komega using simpleFoam
 
Hi,

Omega overshoots and it takes too many iterations to converge p. What could be the probable reason for that? I have checked my mesh with checkMesh command and there was no warnings. Also I have run potentialFoam before running simpleFoam. Thanks.

-----------------------------------------------------------------------
Starting time loop

Time = 1

smoothSolver: Solving for Ux, Initial residual = 0.0539018, Final residual = 5.13197e-05, No Iterations 7
smoothSolver: Solving for Uy, Initial residual = 0.0534879, Final residual = 5.81967e-05, No Iterations 7
smoothSolver: Solving for Uz, Initial residual = 0.354536, Final residual = 6.28499e-05, No Iterations 9
GAMG: Solving for p, Initial residual = 1, Final residual = 8.90323e-05, No Iterations 31
time step continuity errors : sum local = 7.5287e-06, global = 4.65685e-06, cumulative = 4.65685e-06
smoothSolver: Solving for omega, Initial residual = 0.302181, Final residual = 9.99827e-05, No Iterations 768
smoothSolver: Solving for k, Initial residual = 1, Final residual = 8.99188e-05, No Iterations 18
ExecutionTime = 365.58 s ClockTime = 366 s

Time = 2

smoothSolver: Solving for Ux, Initial residual = 0.0158573, Final residual = 5.8239e-05, No Iterations 6
smoothSolver: Solving for Uy, Initial residual = 0.0141884, Final residual = 5.95859e-05, No Iterations 6
smoothSolver: Solving for Uz, Initial residual = 0.290663, Final residual = 5.35847e-05, No Iterations 10
GAMG: Solving for p, Initial residual = 0.359203, Final residual = 9.6866e-05, No Iterations 66
time step continuity errors : sum local = 2.05483e-05, global = -1.10031e-05, cumulative = -6.3463e-06
smoothSolver: Solving for omega, Initial residual = 0.304444, Final residual = 9.18995e-05, No Iterations 11
bounding omega, min: -1.2602e+06 max: 1.4044e+06 average: 3530.71
smoothSolver: Solving for k, Initial residual = 0.0768383, Final residual = 7.52255e-05, No Iterations 18
ExecutionTime = 490.8 s ClockTime = 492 s

Time = 3

smoothSolver: Solving for Ux, Initial residual = 0.000481439, Final residual = 6.82875e-05, No Iterations 2
smoothSolver: Solving for Uy, Initial residual = 0.00038065, Final residual = 5.65517e-05, No Iterations 2
smoothSolver: Solving for Uz, Initial residual = 0.0443271, Final residual = 5.28052e-05, No Iterations 8
GAMG: Solving for p, Initial residual = 0.329192, Final residual = 9.66057e-05, No Iterations 114
time step continuity errors : sum local = 1.50051e-05, global = 6.06992e-07, cumulative = -5.7393e-06
smoothSolver: Solving for omega, Initial residual = 1, Final residual = 0.294131, No Iterations 1000
bounding omega, min: -1735.72 max: 4.64824e+21 average: 2.64451e+15
smoothSolver: Solving for k, Initial residual = 0.200063, Final residual = 1.76944e-09, No Iterations 1
ExecutionTime = 997.83 s ClockTime = 1000 s

----------------------------------------------------------------------

Regards
Jubayer

wyldckat August 26, 2011 13:18

Hi Jubayer,

I have a very little experience with this, but usually the problem you are getting is due to one or more bad boundary conditions on patches. The most probable one is that the boundary conditions for omega are very bad for the case you are running. But that's as far as I can explain, because I can't figure them out either...

Another thing to keep your eyes open for is if your geometry is in another dimensional system other than meters! This could also influence the simulation and lead to crazy results.

Best regards,
Bruno


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