How make F3D to reduce a time step many times down to dtmin?
 

When a number of iterations reaches the maximum limit, F3D reduces time step or declare nonconvergence. I use very small value for the minimum time step limit, however, F3D never reduced time step down to this limit. Moreover, a number of time step reductions can be just one before nonconvergence despite that the time step is still much larger than the limit.
What controls a number of time step reductions? How to make F3D to reduce a time step many times until its value reaches the minimum limit?
Thank you.

Gennady, Have you tried contacting Flow Science, F3D's developer?