I am solving 2D TFM but when I run the simulation an error is coming. I attached a bug report.
Warning from utilities_mod.f:169
lungu_2023-09-09T100614.557560.zip (4.5 MB)
Velocity exceeds limit: 44.000
in cell: I = 2 J = 74 K = 1
Epg = 0.48035 Ug = 0.26045E-02 Vg = -49.256 Wg = 0.0000
To change the limit, adjust the scale factor MAX_INLET_VEL_FAC.
Error from time_step.f:196
DT < DT_MIN. Recovery not possible!
Have you tried the suggestion? To change the limit, adjust the scale factor MAX_INLET_VEL_FAC.
Yes, I tried to adjust the scaler factor of MAX_INLET_VEL_FAC (5-1000). but the problem is not resolved.
A floating point error is coming.
The initial condition is overpacked. Check the values of the solids volume fraction (Initial Conditons>Bed>LLDMP>volume fraction) and the packed bed void fraction (Solids>TFM>Packed bed void fraction, ep_star). If ep_star=0.52, then the initial solids fraction in the bed must be less than 0.48. The GUI should catch the inconsistency if you set ep_star first. It is missing it if ep_star is changed after the bed solids fraction is set.
I’ll add an additional check in the GUI
I changed the initial Solid volume fraction to 0.40 but still problem is same. My question is solid volume fraction in a packed bed is 0.52 then why do we have to select an initial solid volume fraction less than 0.48?
I checked it with different initial solid volume fractions like 0.40, 0.48, and 0.45 but the simulation is not running. the same problem is coming. could you suggest the correct approach?
The error is coming as:
DT < DT_MIN. Recovery not possible!
new_2023-09-14T164019.381241.zip (3.2 MB)
ep_star is void (or fluid) volume fraction, not solid. If void fraction.is 0.52 then solids cannot occupy more than 0.48 since the sum cannot exceed 1
Right, i was applied same thing solid void 0.52, then initial boundary conditions i also applied 0.52 it takes automatically gas voidage 0.48, but simulation is not solving.
The last case you sent ( new_2023-09-14T164019.381241.zip runs fine for me. It has a void fraction at max packing of 0.52, which means solids fraction cannot exceed 0.48, and you set the initial solids fraction in the bed at 0.40 which is below 0.48. This is a valid setting and it runs fine for me.
I run the file you sent me, and even though an error was coming, i did not change any parameters, only reset the job and run.
DT < DT_MIN. Recovery not possible!
new_2023-09-14T164019.381241.zip (3.2 MB)
Message from set_bc0.f:564
Outflow BC defined: IJK_P_g remaining undefined.
t= 0.000000 Wrote SPx: B; .RES;
Recovered: Dt= 0.90000E-03 
Recovered: Dt= 0.81000E-03
Recovered: Dt= 0.72900E-03
Recovered: Dt= 0.65610E-03
Recovered: Dt= 0.59049E-03
Recovered: Dt= 0.53144E-03
Recovered: Dt= 0.47830E-03
Recovered: Dt= 0.43047E-03
Recovered: Dt= 0.38742E-03
Recovered: Dt= 0.34868E-03
Recovered: Dt= 0.31381E-03
Recovered: Dt= 0.28243E-03
Recovered: Dt= 0.25419E-03
Recovered: Dt= 0.22877E-03
Recovered: Dt= 0.20589E-03
Recovered: Dt= 0.18530E-03
Recovered: Dt= 0.16677E-03
Recovered: Dt= 0.15009E-03
Recovered: Dt= 0.13509E-03
Recovered: Dt= 0.12158E-03
Recovered: Dt= 0.10942E-03
Recovered: Dt= 0.98477E-04
Recovered: Dt= 0.88629E-04
Recovered: Dt= 0.79766E-04
Recovered: Dt= 0.71790E-04
Recovered: Dt= 0.64611E-04
Recovered: Dt= 0.58150E-04
Recovered: Dt= 0.52335E-04
Recovered: Dt= 0.47101E-04
Recovered: Dt= 0.42391E-04
Recovered: Dt= 0.38152E-04
Recovered: Dt= 0.34337E-04
Recovered: Dt= 0.30903E-04
Recovered: Dt= 0.27813E-04
Recovered: Dt= 0.25032E-04
Recovered: Dt= 0.22528E-04
Recovered: Dt= 0.20276E-04
Recovered: Dt= 0.18248E-04
Recovered: Dt= 0.16423E-04
Recovered: Dt= 0.14781E-04
Recovered: Dt= 0.13303E-04
Recovered: Dt= 0.11973E-04
Recovered: Dt= 0.10775E-04
Recovered: Dt= 0.96977E-05
Recovered: Dt= 0.87280E-05
Recovered: Dt= 0.78552E-05
Recovered: Dt= 0.70697E-05
Recovered: Dt= 0.63627E-05
Recovered: Dt= 0.57264E-05
Recovered: Dt= 0.51538E-05
Recovered: Dt= 0.46384E-05
Recovered: Dt= 0.41746E-05
Recovered: Dt= 0.37571E-05
Recovered: Dt= 0.33814E-05
Recovered: Dt= 0.30433E-05
Recovered: Dt= 0.27389E-05
Recovered: Dt= 0.24650E-05
Recovered: Dt= 0.22185E-05
Recovered: Dt= 0.19967E-05
Recovered: Dt= 0.17970E-05
Recovered: Dt= 0.16173E-05
Recovered: Dt= 0.14556E-05
Recovered: Dt= 0.13100E-05
Recovered: Dt= 0.11790E-05
Recovered: Dt= 0.10611E-05
Error from time_step.f:196
DT < DT_MIN. Recovery not possible!
Fatal error reported on one or more processes. The .LOG file
may contain additional information about the failure.
MFiX process has stopped
Previous MFiX run is resumable. Reset job to edit model
Ready
bc_ep_s(2,1)
bc_ep_g(2) = 1.0
When I run your simulation on my machine, the time step drops but it doesn’t reach DT_MIN, and then it goes back up:
MESH STATISTICS:
NUMBER OF CELLS = 6000
NUMBER OF STANDARD CELLS = 6000 (100.00 % of Total)
NUMBER OF CUT CELLS = 0 ( 0.00 % of Total)
NUMBER OF FLUID CELLS = 6000 (100.00 % of Total)
NUMBER OF BLOCKED CELLS = 0 ( 0.00 % of Total)
WROTE BOUNDARY IN VTK FILE : NEW_boundary.vtk
PRE_PROCESSING COMPLETE.
Message from set_bc0.f:564
Outflow BC defined: IJK_P_g remaining undefined.
t= 0.000000 Wrote SPx: B; .RES;
Recovered: Dt= 0.90000E-03 :-)
Recovered: Dt= 0.81000E-03 :-)
Recovered: Dt= 0.72900E-03 :-)
Recovered: Dt= 0.65610E-03 :-)
Recovered: Dt= 0.59049E-03 :-)
Recovered: Dt= 0.53144E-03 :-)
Recovered: Dt= 0.47830E-03 :-)
Recovered: Dt= 0.43047E-03 :-)
Recovered: Dt= 0.38742E-03 :-)
Recovered: Dt= 0.34868E-03 :-)
Recovered: Dt= 0.31381E-03 :-)
Recovered: Dt= 0.28243E-03 :-)
t= 0.0000 Dt= 0.2824E-03 NIT= 43 Sm= 22.032 Hl= 0.0000 CPU= 8.s
Mass imbalance%(0,MMAX): -0.6390E-04 0.1903E-11
Timestep walltime, fluid solver: 8.231 s
Recovered: Dt= 0.25419E-03 :-)
Recovered: Dt= 0.22877E-03 :-)
Recovered: Dt= 0.20589E-03 :-)
Recovered: Dt= 0.18530E-03 :-)
Recovered: Dt= 0.16677E-03 :-)
Recovered: Dt= 0.15009E-03 :-)
Recovered: Dt= 0.13509E-03 :-)
Recovered: Dt= 0.12158E-03 :-)
Recovered: Dt= 0.10942E-03 :-)
Recovered: Dt= 0.98477E-04 :-)
Recovered: Dt= 0.88629E-04 :-)
Recovered: Dt= 0.79766E-04 :-)
Recovered: Dt= 0.71790E-04 :-)
Recovered: Dt= 0.64611E-04 :-)
Recovered: Dt= 0.58150E-04 :-)
Recovered: Dt= 0.52335E-04 :-)
Recovered: Dt= 0.47101E-04 :-)
Recovered: Dt= 0.42391E-04 :-)
Recovered: Dt= 0.38152E-04 :-)
Recovered: Dt= 0.34337E-04 :-)
Recovered: Dt= 0.30903E-04 :-)
Recovered: Dt= 0.27813E-04 :-)
Recovered: Dt= 0.25032E-04 :-)
Recovered: Dt= 0.22528E-04 :-)
Recovered: Dt= 0.20276E-04 :-)
Recovered: Dt= 0.18248E-04 :-)
Recovered: Dt= 0.16423E-04 :-)
Recovered: Dt= 0.14781E-04 :-)
Recovered: Dt= 0.13303E-04 :-)
Recovered: Dt= 0.11973E-04 :-)
Recovered: Dt= 0.10775E-04 :-)
Recovered: Dt= 0.96977E-05 :-)
Timestep walltime, fluid solver: 14.819 s
Timestep walltime, fluid solver: 0.406 s
Timestep walltime, fluid solver: 0.117 s
Timestep walltime, fluid solver: 0.095 s
Timestep walltime, fluid solver: 0.073 s
DT= 0.1078E-04 NIT/s=1072415
Timestep walltime, fluid solver: 0.203 s
Timestep walltime, fluid solver: 0.101 s
Timestep walltime, fluid solver: 0.096 s
Timestep walltime, fluid solver: 0.095 s
Timestep walltime, fluid solver: 0.073 s
Timestep walltime, fluid solver: 0.101 s
DT= 0.1197E-04 NIT/s=352660
Timestep walltime, fluid solver: 0.074 s
Timestep walltime, fluid solver: 0.073 s
Timestep walltime, fluid solver: 0.186 s
Timestep walltime, fluid solver: 0.074 s
Timestep walltime, fluid solver: 0.080 s
Timestep walltime, fluid solver: 0.096 s
DT= 0.1330E-04 NIT/s=267279
Timestep walltime, fluid solver: 0.074 s
Timestep walltime, fluid solver: 0.074 s
Timestep walltime, fluid solver: 0.053 s
Timestep walltime, fluid solver: 0.057 s
Timestep walltime, fluid solver: 0.051 s
Timestep walltime, fluid solver: 0.052 s
DT= 0.1478E-04 NIT/s=165379
Please try to increase the number of iterations in the pressure correction to 100. This should help with the initial non-convergence:
