Fatal error reported on one or more processes

Dear Mfix Expert,
I am working on a 3D case TFM and have coupled a UDF that shows a successful build when I build using the debug flag. However, when I run the simulation, it doesn’t start and displays the error message ‘Fatal error reported on one or more processes.’
I am having trouble tracking down the source of the error. I have checked my UDF and even tested it in the Fortran compiler, which gave the expected value. Even when I included a print command in the code, the simulation hangs on. Although I have used this UDF in 2D simulations and it has worked, the same UDF does not solve the problem in 3D simulations.
I am not sure how to track the simulation and solve these types of errors in MFix. The error message ‘DT < DT_MIN. Recovery not possible!’ always shows up, but I don’t understand where the error is coming from. Please help.

Compressible: IJK_P_g remaining undefined.

Error from time_step.f:198

DT < DT_MIN. Recovery is not possible!

Fatal error reported on one or more processes. The. LOG file

may contain additional information about the failure.

The MFiX process has stopped

The previous MFiX run is resumable.

3dcase_2024-04-08T192021.454034.zip (29.4 MB)

Dear Mfix users,
I am eagerly waiting for your reply please help me, why Mfix doesn’t give source of error, so that we can trace or debug the problem easily, in maximum cases error gives DT < DT_MIN. Recovery is not possible!
Then how can i know the source of error.

Dear @jeff.dietiker
could you pls help me to resolve the thermal conductivity problem,
I am simulating TFM and applied usr.properties.f for kg and ks. I tracked the problem and found that the problem is coming to get the value of k_g(IJK) value, when i use K_g(IJK) = (1.0 - (SQRT(1.0 - ep_g(IJK)))) simulation is running but when i used K_g(IJK) = (1.0 - (SQRT(1.0 - ep_g(IJK)))) * (0.0257 / ep_g(IJK)). then the simulation is not starting and an error is comes “DT < DT_MIN. Recovery is not possible!
ep_g(IJK) value comes 1.0 in most of the cell.

! Modules
use fldvar, ONLY: ep_g
use param1, only: zero
use physprop, only: k_g
implicit none

! Dummy arguments

! Assign the fluid conductivity

! print *, "ep_g(IJK) =", ep_g(IJK)

 IF (ep_g(IJK) < 1.0 ) THEN
  K_g(IJK) = (1.0 - (SQRT(1.0 - ep_g(IJK)))) * (0.0257 / ep_g(IJK))

    K_g(IJK) = 0.0257