Reply To: Divergence problem of the spray simulation with Eulerian wall film

[azhao]

Hi Rob I followed your suggestion by changing the particle stream number to 25 and running the case again, it went a little bit farther than before but blew off after 31 iterations, the following is the error message, I can find several parts that are suspicious:
the part marked by !!!!! looks very strange but I assume it is only an issue related to parallel computation but not convergence?
The number of parcels is heavily reduced but still quite a lot, maybe I shall decrease the particle stream further?
The direct cause seems to be the excessive CFL number, but I am not sure what does this CFL number mean. I think the coupled solution algorithm itself is implicit, so maybe the problem is because the first order explicit way selected by Eulerian wall film model? I will change it and have a try......
The two turbulence closure equations seem to be another problem as the last two columns have very big residuals. and the warning "turbulent viscosity limited to viscosity ratio of 1.000000e+05 in 719163 cells", no idea if I should do something to improve this or it will disappear after the convergence problem is solved.
Thanks for checking this long thread.
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Advancing DPM injections...

Reversed flow on 11521 faces (62.6% area) of pressure-outlet 12.

Reversed flow on 10117 faces (56.1% area) of pressure-outlet 13.

Reversed flow on 7590 faces (99.7% area) of pressure-outlet 14.
temperature limited to 1.000000e+00 in 680 cells on zone 10 in domain 1
temperature limited to 5.000000e+03 in 5 cells on zone 10 in domain 1
Film time = 1.300018e-03 with timestep = 3.1e-09, (max_cfl: 1.805477e-01)

Eulerian wall film model is enabled:

!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!
The use of the DPM Domain has been requested, but it is incompatible with the above
settings, and therefore the DPM Domain will not be used.
To avoid this message, disable the 'Use DPM Domain' option.
You may want to use the 'Hybrid Optimization' in the partitioning options instead.
That is, enable it, run some DPM iterations, repartition, and use the new partitions.
!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!

Injecting 25 particle parcels with mass 1e-07
number tracked = 475615, escaped = 20, incomplete = 471972, shed = 473897
Eulerian wall film particles:
absorbed = 328, splashed = 64, stripped = 74, rebound = 38
Injecting 25 particle parcels with mass 1e-07
number tracked = 477099, escaped = 105, incomplete = 472289, shed = 1479
Eulerian wall film particles:
absorbed = 759, splashed = 312, stripped = 36, rebound = 43
Injecting 25 particle parcels with mass 1e-07
number tracked = 477701, escaped = 59, incomplete = 472274, shed = 1267
Eulerian wall film particles:
absorbed = 418, splashed = 96, stripped = 36, rebound = 28
Injecting 25 particle parcels with mass 1e-07
number tracked = 478676, escaped = 50, incomplete = 471996, shed = 1223
Eulerian wall film particles:
absorbed = 647, splashed = 180, stripped = 36, rebound = 40
Injecting 25 particle parcels with mass 1e-07
number tracked = 479681, escaped = 68, incomplete = 472161, shed = 1376
Eulerian wall film particles:
absorbed = 654, splashed = 256, stripped = 36, rebound = 26
Injecting 25 particle parcels with mass 1e-07
number tracked = 480179, escaped = 54, incomplete = 472022, shed = 955
Eulerian wall film particles:
absorbed = 630, splashed = 176, stripped = 36, rebound = 29
Injecting 25 particle parcels with mass 1e-07
number tracked = 481179, escaped = 39, incomplete = 472086, shed = 1331
Eulerian wall film particles:
absorbed = 595, splashed = 284, stripped = 36, rebound = 23
Injecting 25 particle parcels with mass 1e-07
number tracked = 482245, escaped = 36, incomplete = 472225, shed = 1192
Eulerian wall film particles:
absorbed = 887, splashed = 412, stripped = 36, rebound = 69
Injecting 25 particle parcels with mass 1e-07
number tracked = 483065, escaped = 38, incomplete = 472233, shed = 1435
Eulerian wall film particles:
absorbed = 646, splashed = 180, stripped = 36, rebound = 44
Injecting 25 particle parcels with mass 1e-07
number tracked = 484070, escaped = 37, incomplete = 472416, shed = 1363
Eulerian wall film particles:
absorbed = 756, splashed = 256, stripped = 36, rebound = 32

Warning:3.2923% of the total discrete phase mass was not tracked for the expected residence time:
7.53e-05 s less on a mass-weighted average (which is 12.5713% of their total age or 7.5307% of the last time step).


turbulent viscosity limited to viscosity ratio of 1.000000e+05 in 223317 cells
303.8262e-041.4659e-031.1315e-033.5500e-033.9687e-038.1724e-015.7855e-01 168:57:16 19970

Reversed flow on 10765 faces (55.8% area) of pressure-outlet 12.

Reversed flow on 7856 faces (48.8% area) of pressure-outlet 13.

Reversed flow on 5505 faces (69.9% area) of pressure-outlet 14.
Stabilizing pressure coupled to enhance linear solver robustness.
Stabilizing pressure coupled using GMRES to enhance linear solver robustness.

Experiencing convergence difficulties - temporarily relaxing and trying again...
Stabilizing pressure coupled to enhance linear solver robustness.
Negative k in 1044 cells after linear solve.
temperature limited to 1.000000e+00 in 59751 cells on zone 10 in domain 1
temperature limited to 5.000000e+03 in 74 cells on zone 10 in domain 1
Film time = 1.300021e-03 with timestep = 3.1e-09, (max_cfl: 3.909367e-01)
Maximum CFL reached. Reduce time step by factor of 2

turbulent viscosity limited to viscosity ratio of 1.000000e+05 in 655349 cells
311.0179e-021.7508e-152.3064e-153.7564e-153.8050e-132.1808e+021.0341e+00 143:24:54 19969

Reversed flow on 10938 faces (56.5% area) of pressure-outlet 12.

Reversed flow on 8033 faces (48.1% area) of pressure-outlet 13.

Reversed flow on 6093 faces (78.6% area) of pressure-outlet 14.
Stabilizing pressure coupled to enhance linear solver robustness.
Stabilizing pressure coupled using GMRES to enhance linear solver robustness.

Experiencing convergence difficulties - temporarily relaxing and trying again...
Stabilizing pressure coupled to enhance linear solver robustness.
Stabilizing pressure coupled using GMRES to enhance linear solver robustness.

Experiencing convergence difficulties - temporarily relaxing and trying again...

Divergence detected in AMG solver: pressure coupledStabilizing k to enhance linear solver robustness.
Negative k in 202201 cells after linear solve.
All neighbors negative on 11 cells.
temperature limited to 1.000000e+00 in 333900 cells on zone 10 in domain 1
temperature limited to 5.000000e+03 in 532 cells on zone 10 in domain 1
Film time = 1.300023e-03 with timestep = 1.5e-09, (max_cfl: 1.108611e+00)
Maximum CFL reached. Reduce time step by factor of 2

turbulent viscosity limited to viscosity ratio of 1.000000e+05 in 719163 cells

Divergence detected in AMG solver: pressure coupled