FLUENT DPM unsteady particle time step VS injection time step
 

The user manual says " You can either Inject Particles at Particle Time step or at the flow time step."

Is it possible to setup a user defined injection time step in unsteady tracking, which is different from the particle tracking time step?

For example, I want to study particles in its mean free path without any collisions.

I know the particle flow rate, say 1E7 particles injected per second. And I know the time corresponding to its mean free path say 1E-10s.

If I set the particle tracking time step is 1E-10s, then because of "injection time step=tracking time step", then I injected 1E-10s * 1E7/s =1E-3 particles. This is unphysical! The particle number should be integer, at least 1.

Who could provide some suggestion in the above scenario?

Thank you.

WW