[MaryBau]

Hi everyone;

I am having some problems with my simulations. They crashed all of a sudden. Usually the iterations of k increase (sometime is the velocity), then deltaT becomes really small and a couple time steps after the sim crashes. This is an example of the output:

Time = 56.3014205783

Courant Number mean: 0.118327767573 max: 0.19896182766
deltaT = 0.00153197241597
DILUPBiCG:  Solving for Ux, Initial residual = 0.00174185441499, Final residual = 4.59171443112e-09, No Iterations 3
DILUPBiCG:  Solving for Uy, Initial residual = 0.0180925560235, Final residual = 5.51828116172e-08, No Iterations 3
DILUPBiCG:  Solving for Uz, Initial residual = 0.0208771839438, Final residual = 5.52651987859e-08, No Iterations 3
GAMG:  Solving for p, Initial residual = 0.0786783298856, Final residual = 5.28569419341e-06, No Iterations 9
time step continuity errors : sum local = 2.29595919923e-10, global = 1.15432066317e-19, cumulative = -8.84673137504e-16
GAMG:  Solving for p, Initial residual = 0.00333261520514, Final residual = 9.92201073873e-07, No Iterations 7
time step continuity errors : sum local = 4.30705321016e-11, global = -1.31772997273e-18, cumulative = -8.85990867476e-16
GAMG:  Solving for p, Initial residual = 0.000138442060363, Final residual = 7.07661072868e-07, No Iterations 6
time step continuity errors : sum local = 3.53898112737e-11, global = -7.05569157603e-19, cumulative = -8.86696436634e-16
DILUPBiCG:  Solving for omega, Initial residual = 7.00026119366e-07, Final residual = 3.58270229366e-09, No Iterations 1
DILUPBiCG:  Solving for k, Initial residual = 0.00115615362982, Final residual = 2.81404703888e-09, No Iterations 3
bounding k, min: 0 max: 0.586278690722 average: 0.0996495165825
ExecutionTime = 75598.44 s  ClockTime = 75928 s

Calculating averages


Time = 56.3029525507

Courant Number mean: 0.118847270725 max: 0.198956109975
deltaT = 0.0015387360911
DILUPBiCG:  Solving for Ux, Initial residual = 0.00174945388057, Final residual = 4.68860801279e-09, No Iterations 3
DILUPBiCG:  Solving for Uy, Initial residual = 0.018172002406, Final residual = 5.60114718505e-08, No Iterations 3
DILUPBiCG:  Solving for Uz, Initial residual = 0.0209706723416, Final residual = 5.64116133548e-08, No Iterations 3
GAMG:  Solving for p, Initial residual = 0.0789601498487, Final residual = 6.87653606352e-06, No Iterations 9
time step continuity errors : sum local = 3.17562391533e-10, global = 3.71130246033e-19, cumulative = -8.86325306388e-16
GAMG:  Solving for p, Initial residual = 0.00338734796122, Final residual = 9.66446829089e-07, No Iterations 31
time step continuity errors : sum local = 5.06496323068e-11, global = -5.9961362602e-19, cumulative = -8.86924920014e-16
GAMG:  Solving for p, Initial residual = 0.000140735396748, Final residual = 6.27831105034e-07, No Iterations 5
time step continuity errors : sum local = 2.65259351068e-11, global = -2.82758134623e-19, cumulative = -8.87207678149e-16
DILUPBiCG:  Solving for omega, Initial residual = 7.02406726747e-07, Final residual = 3.61836938681e-09, No Iterations 1
DILUPBiCG:  Solving for k, Initial residual = 0.00116106584398, Final residual = 166169.798741, No Iterations 1001
bounding k, min: -312205129.035 max: 269273680.127 average: -10606.0281394
ExecutionTime = 75608.43 s  ClockTime = 75938 s

Calculating averages

Time = 56.3044912868

Courant Number mean: 0.119372303823 max: 0.198738491473
deltaT = 0.00154557491817
DILUPBiCG:  Solving for Ux, Initial residual = 0.994347884301, Final residual = 9.44225468604e-08, No Iterations 189
DILUPBiCG:  Solving for Uy, Initial residual = 0.908777437471, Final residual = 9.09721357325e-08, No Iterations 201
DILUPBiCG:  Solving for Uz, Initial residual = 0.918085844451, Final residual = 8.23188861914e-08, No Iterations 266
GAMG:  Solving for p, Initial residual = 0.999894333283, Final residual = 9.98918535975e-05, No Iterations 534
time step continuity errors : sum local = 5.88051660082e-06, global = 1.07090381147e-16, cumulative = -7.80117297001e-16
GAMG:  Solving for p, Initial residual = 0.600725392574, Final residual = 5.96105999062e-05, No Iterations 429
time step continuity errors : sum local = 7.48767985205e-06, global = 7.86420631943e-17, cumulative = -7.01475233807e-16
GAMG:  Solving for p, Initial residual = 0.191758582659, Final residual = 9.96774342026e-07, No Iterations 817
time step continuity errors : sum local = 1.22807359407e-07, global = -4.48319516578e-16, cumulative = -1.14979475038e-15
DILUPBiCG:  Solving for omega, Initial residual = 0.908220760948, Final residual = 3.49400568529, No Iterations 1001
bounding omega, min: -8784737312 max: 13428850393.2 average: 5500413.94033
DILUPBiCG:  Solving for k, Initial residual = 0.999995075281, Final residual = 0.00454874595929, No Iterations 1001
bounding k, min: -1.41020644379e+12 max: 2.66411047567e+12 average: 111889394.608
ExecutionTime = 75668.23 s  ClockTime = 75998 s

The most puzzling thing is that I cannot reproduce the "crash", to save it and visualize it for example. If I rerun the simulation without any change (starting at the last saved time), it runs pass the previous crashing point.

I have tried changing pretty much every option in the fvSolution and fvSchemes. But I have not been able to identify the problem. Any suggestions or ideas?


Info about my case:

- Simulations of a simplified atmospheric boundary layer so it is basically a channel flow.
- I am using a hybrid model (k-w SST-IDDES).
- There is nothing fancy about the mesh. Rectangle with rectangular cells, that are really elongated close to the wall


Thanks a lot,

Mary