settlingFoam crash when velocity increase
 

Dear Foamers,

I have built a case with settlingFoam in open channel and succeeded to implement settlingFoam with upstream velocity U=0.01m/s. But when I increase velocity to 0.1m/s and then decrease deltaT to 1/10 of original value with other parameters unchanged, settlingFoam crash only in a few steps.

I have checked the mesh and other parameters, they all seem ok. And the successful run with velocity U=0.01m/s also verify the correctness of the model.

So where is the problem?

Please help check it
https://www.dropbox.com/s/avyqgvppc5...ingFoamTry.rar

Thank you so much!

The error are:
[4] --> FOAM FATAL IO ERROR:
[4] wrong token type - expected Scalar, found on line 6 the word 'nan'
[4]
[4] file: /work/jchb_work/tryCase3/processor4/system/data.solverPerformance.p_rgh at line 6.
[4]
[4] From function operator>>(Istream&, Scalar&)
[4] in file lnInclude/Scalar.C at line 91.
[4]
FOAM parallel run exiting


and

the last few outputs before crash
Courant Number mean: 157.258 max: 2.78008e+09
Time = 0.0035

diagonal: Solving for rho, Initial residual = 0, Final residual = 0, No Iterations 0
DILUPBiCG: Solving for Ux, Initial residual = 0.961496, Final residual = 21.6592, No Iterations 1001
DILUPBiCG: Solving for Uy, Initial residual = 0.479107, Final residual = 66.819, No Iterations 1001
DILUPBiCG: Solving for Uz, Initial residual = 0.989586, Final residual = 1181.08, No Iterations 1001
DILUPBiCG: Solving for Alpha, Initial residual = 7.05917e-29, Final residual = 7.05917e-29, No Iterations 0
Solid phase fraction = 7.59423e-09 Min(Alpha) = 0 Max(Alpha) = 0.0001
DICPCG: Solving for p_rgh, Initial residual = 1, Final residual = 0.00937167, No Iterations 285
diagonal: Solving for rho, Initial residual = 0, Final residual = 0, No Iterations 0
time step continuity errors : sum local = 1.56205e+10, global = 3.54897e+09, cumulative = 1.88911e+10
DICPCG: Solving for p_rgh, Initial residual = 1, Final residual = 1161.01, No Iterations 1001
diagonal: Solving for rho, Initial residual = 0, Final residual = 0, No Iterations 0
time step continuity errors : sum local = -1.76542e+77, global = 1.14126e+79, cumulative = 1.14126e+79
DILUPBiCG: Solving for epsilon, Initial residual = 1.04384e-16, Final residual = 1.04384e-16, No Iterations 0
DILUPBiCG: Solving for k, Initial residual = 3.74426e-10, Final residual = 3.74426e-10, No Iterations 0
ExecutionTime = 31.49 s ClockTime = 31 s

Courant Number mean: 9.93646e+06 max: 2.91565e+14
Time = 0.004

diagonal: Solving for rho, Initial residual = 0, Final residual = 0, No Iterations 0
DILUPBiCG: Solving for Ux, Initial residual = 0.385816, Final residual = 3.31484e-08, No Iterations 152
DILUPBiCG: Solving for Uy, Initial residual = 0.586937, Final residual = 7.98723e-08, No Iterations 48
DILUPBiCG: Solving for Uz, Initial residual = 0.426142, Final residual = 9.93456e-08, No Iterations 30
DILUPBiCG: Solving for Alpha, Initial residual = 0.00565905, Final residual = 6.1556e-08, No Iterations 15
Solid phase fraction = 7.75057e-09 Min(Alpha) = -3.91074e-07 Max(Alpha) = 0.0001
DICPCG: Solving for p_rgh, Initial residual = 1, Final residual = 3324.1, No Iterations 1001
diagonal: Solving for rho, Initial residual = 0, Final residual = 0, No Iterations 0
time step continuity errors : sum local = 5.58815e+73, global = 5.56881e+73, cumulative = 1.14127e+79
DICPCG: Solving for p_rgh, Initial residual = 1, Final residual = nan, No Iterations 1001
diagonal: Solving for rho, Initial residual = 0, Final residual = 0, No Iterations 0
time step continuity errors : sum local = nan, global = nan, cumulative = nan
DILUPBiCG: Solving for epsilon, Initial residual = nan, Final residual = nan, No Iterations 1001
DILUPBiCG: Solving for k, Initial residual = nan, Final residual = nan, No Iterations 1001
ExecutionTime = 47.43 s ClockTime = 47 s

Courant Number mean: nan max: nan
Time = 0.0045

diagonal: Solving for rho, Initial residual = 0, Final residual = 0, No Iterations 0
DILUPBiCG: Solving for Ux, Initial residual = nan, Final residual = nan, No Iterations 1001
DILUPBiCG: Solving for Uy, Initial residual = nan, Final residual = nan, No Iterations 1001
DILUPBiCG: Solving for Uz, Initial residual = nan, Final residual = nan, No Iterations 1001
DILUPBiCG: Solving for Alpha, Initial residual = nan, Final residual = nan, No Iterations 1001
Solid phase fraction = nan Min(Alpha) = nan Max(Alpha) = nan
DICPCG: Solving for p_rgh, Initial residual = nan, Final residual = nan, No Iterations 1001
diagonal: Solving for rho, Initial residual = 0, Final residual = 0, No Iterations 0
time step continuity errors : sum local = nan, global = nan, cumulative = nan
DICPCG: Solving for p_rgh, Initial residual = nan, Final residual = nan, No Iterations 1001

I'e tried using the 'adaptive timestep. control, which times the timestep down to c. 1E-27 to control the Courant number. I've tried changing the outlet boundary. No success.

Your grid has some small cells around the middle - is this trying to represent settling around a heat exchanger bundle?

I think you may have to try and change the integration method from explicit to implicit. I haven't tried that.