By the way, I have a complementary question regarding how the time step is calculated in both the steady and unsteady DPM cases. This time step is required for the equation of motion of the particles. 

I know that in the steady mode, the user can give either the "step length factor" or the "length scale". However, in the unsteady DPM case, this panel remains active even though the user will assign a particle time step directly. In the unsteady DPM case, what is the use of the "step length factor" or the "length scale"? 

Will they be ignored and only the DPM time step will be considered maybe?