KNOWN ISSUE: Use of time step in particle user routines (Class 3 Error)
The particle integration timestep is an argument that can be used in particle user routines, especially the particle source routines. If the timestep is used in these Fortran routines, then incorrect answers will be obtained.
PROBLEM: The timestep that is passed to the user routine is not the actual timestep being used by the integrator. The argument passed in error will be correct on many timesteps, but will be too large for some steps.
No workaround is currently available.
ANSYS CFX Release 13.0. A custom executable for ANSYS CFX Release 12.1 is available on request.