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-   -   epsilon and K blowing up. (http://www.cfd-online.com/Forums/openfoam-solving/108433-epsilon-k-blowing-up.html)

sivakumar October 23, 2012 13:07

epsilon and K blowing up.
 
Hi everyone,
Thank you very much for your support so for. I am running MRFSimpleFoam. My problem getting diverged.

I tried many different ways playing around fvSolution 0/U and 0/P, but I am not at all getting the solution converged.

Even I have changed the mesh as well, but still i am getting the same problem.

Fomers please help me to solve this problem.
I am giving the some information here, please have a look and help me to solve this problem.

Time = 225

smoothSolver: Solving for Ux, Initial residual = 0.00565597, Final residual = 1.96192e-06, No Iterations 6
smoothSolver: Solving for Uy, Initial residual = 0.00516823, Final residual = 2.10924e-06, No Iterations 6
smoothSolver: Solving for Uz, Initial residual = 0.00714336, Final residual = 3.27299e-06, No Iterations 6
GAMG: Solving for p, Initial residual = 0.055741, Final residual = 9.43727e-05, No Iterations 9
GAMG: Solving for p, Initial residual = 0.00490433, Final residual = 8.61346e-05, No Iterations 4
time step continuity errors : sum local = 0.00165288, global = 2.88568e-05, cumulative = -0.00884124
smoothSolver: Solving for epsilon, Initial residual = 0.00817578, Final residual = 3.09729e-06, No Iterations 6
bounding epsilon, min: -186.143 max: 5.97642e+06 average: 5211.32
smoothSolver: Solving for k, Initial residual = 0.00800929, Final residual = 3.90832e-06, No Iterations 6
ExecutionTime = 10638 s ClockTime = 10716 s

Time = 226

smoothSolver: Solving for Ux, Initial residual = 0.00564199, Final residual = 1.97005e-06, No Iterations 6
smoothSolver: Solving for Uy, Initial residual = 0.00518653, Final residual = 2.114e-06, No Iterations 6
smoothSolver: Solving for Uz, Initial residual = 0.00715259, Final residual = 3.28843e-06, No Iterations 6
GAMG: Solving for p, Initial residual = 0.0556293, Final residual = 9.66526e-05, No Iterations 9
GAMG: Solving for p, Initial residual = 0.00486369, Final residual = 8.6384e-05, No Iterations 4
time step continuity errors : sum local = 0.00165773, global = 2.85691e-05, cumulative = -0.00881267
smoothSolver: Solving for epsilon, Initial residual = 0.00819642, Final residual = 3.09749e-06, No Iterations 6
bounding epsilon, min: -75.4973 max: 5.99812e+06 average: 5229.72
smoothSolver: Solving for k, Initial residual = 0.00802679, Final residual = 3.92315e-06, No Iterations 6
ExecutionTime = 10679.1 s ClockTime = 10757 s

Time = 227

smoothSolver: Solving for Ux, Initial residual = 0.00562736, Final residual = 1.97889e-06, No Iterations 6
smoothSolver: Solving for Uy, Initial residual = 0.00519417, Final residual = 2.1156e-06, No Iterations 6
smoothSolver: Solving for Uz, Initial residual = 0.0071539, Final residual = 3.30093e-06, No Iterations 6
GAMG: Solving for p, Initial residual = 0.0551933, Final residual = 6.24447e-05, No Iterations 10
GAMG: Solving for p, Initial residual = 0.00478002, Final residual = 8.33402e-05, No Iterations 4
time step continuity errors : sum local = 0.0016107, global = 5.01924e-05, cumulative = -0.00876247
smoothSolver: Solving for epsilon, Initial residual = 0.00819635, Final residual = 3.10061e-06, No Iterations 6
bounding epsilon, min: -476.816 max: 6.01902e+06 average: 5248.5
smoothSolver: Solving for k, Initial residual = 0.00802066, Final residual = 3.9252e-06, No Iterations 6
ExecutionTime = 10721 s ClockTime = 10799 s

Time = 228

smoothSolver: Solving for Ux, Initial residual = 0.00560827, Final residual = 1.98593e-06, No Iterations 6
smoothSolver: Solving for Uy, Initial residual = 0.00516854, Final residual = 2.10367e-06, No Iterations 6
smoothSolver: Solving for Uz, Initial residual = 0.00712798, Final residual = 3.29982e-06, No Iterations 6
GAMG: Solving for p, Initial residual = 0.0547901, Final residual = 6.15875e-05, No Iterations 10
GAMG: Solving for p, Initial residual = 0.00470797, Final residual = 8.27801e-05, No Iterations 4
time step continuity errors : sum local = 0.00161088, global = 4.80099e-05, cumulative = -0.00871446
smoothSolver: Solving for epsilon, Initial residual = 0.00813391, Final residual = 3.07376e-06, No Iterations 6
bounding epsilon, min: -11.1399 max: 6.03917e+06 average: 5267.65
smoothSolver: Solving for k, Initial residual = 0.00793759, Final residual = 3.90008e-06, No Iterations 6
ExecutionTime = 10762.7 s ClockTime = 10841 s

Time = 229

smoothSolver: Solving for Ux, Initial residual = 0.00559746, Final residual = 1.99705e-06, No Iterations 6
smoothSolver: Solving for Uy, Initial residual = 0.00519349, Final residual = 2.11399e-06, No Iterations 6
smoothSolver: Solving for Uz, Initial residual = 0.00714505, Final residual = 3.32027e-06, No Iterations 6
GAMG: Solving for p, Initial residual = 0.054808, Final residual = 6.01202e-05, No Iterations 10
GAMG: Solving for p, Initial residual = 0.00468023, Final residual = 8.32608e-05, No Iterations 4
time step continuity errors : sum local = 0.00161895, global = 4.82086e-05, cumulative = -0.00866626
smoothSolver: Solving for epsilon, Initial residual = 0.00817125, Final residual = 3.08408e-06, No Iterations 6
bounding epsilon, min: -102.506 max: 6.05861e+06 average: 5287.15
smoothSolver: Solving for k, Initial residual = 0.00796752, Final residual = 3.91071e-06, No Iterations 6
ExecutionTime = 10804.5 s ClockTime = 10883 s

Time = 230

smoothSolver: Solving for Ux, Initial residual = 0.00557917, Final residual = 2.00559e-06, No Iterations 6
smoothSolver: Solving for Uy, Initial residual = 0.00517033, Final residual = 2.10464e-06, No Iterations 6
smoothSolver: Solving for Uz, Initial residual = 0.00712227, Final residual = 3.32121e-06, No Iterations 6
GAMG: Solving for p, Initial residual = 0.0542311, Final residual = 5.942e-05, No Iterations 10
GAMG: Solving for p, Initial residual = 0.00460901, Final residual = 8.25014e-05, No Iterations 4
time step continuity errors : sum local = 0.00161992, global = 4.8076e-05, cumulative = -0.00861818
smoothSolver: Solving for epsilon, Initial residual = 0.00811242, Final residual = 3.06679e-06, No Iterations 6
bounding epsilon, min: -779.869 max: 6.07742e+06 average: 5306.99
smoothSolver: Solving for k, Initial residual = 0.00789177, Final residual = 3.88282e-06, No Iterations 6
ExecutionTime = 10846.4 s ClockTime = 10925 s

Time = 231

smoothSolver: Solving for Ux, Initial residual = 0.00556631, Final residual = 2.01729e-06, No Iterations 6
smoothSolver: Solving for Uy, Initial residual = 0.00518156, Final residual = 2.11107e-06, No Iterations 6
smoothSolver: Solving for Uz, Initial residual = 0.00712905, Final residual = 3.33756e-06, No Iterations 6
GAMG: Solving for p, Initial residual = 0.0539533, Final residual = 5.90727e-05, No Iterations 10
GAMG: Solving for p, Initial residual = 0.00455727, Final residual = 8.22762e-05, No Iterations 4
time step continuity errors : sum local = 0.00162244, global = 4.80901e-05, cumulative = -0.00857009
smoothSolver: Solving for epsilon, Initial residual = 0.00812008, Final residual = 3.06666e-06, No Iterations 6
bounding epsilon, min: -11.1692 max: 6.09563e+06 average: 5327.14
smoothSolver: Solving for k, Initial residual = 0.00789245, Final residual = 3.89291e-06, No Iterations 6
ExecutionTime = 10888.1 s ClockTime = 10967 s

the epsilon keep on increasing, how can i fix this problem.


Thanks in advance for your help.

sivakumar

thg October 25, 2012 04:50

Hi Shvakumar,

i) use upwind schemes for k and epsilon
ii) initialize k and epsilon proper (f.i. deriving i.c./b.c. from intensity/length scale assumptions)assumptions)
iii) check you schemes and change maybe.
f.i. from linear to limitedLinear.

Best
Th.


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