Software for particle-particle interaction
 

Is there any commercial software to consider particle-particle interaction including collision and fragmentation in a turbulent flow in lagrangian approach? And/or there is this capability to introduce some user defined functions (UDFs) in order to define the aforementioned phenomena into the software?

Fluent has multiphase capabilities designed for discrete particles in flow. I have not used it outside of a training class but it sounds like it can do what you want it do. You can build your own UDFs in fluent; it can be a bit tricky so try going through some examples.

I also think that Star-CCM+ can do it too, yet I have no experience with it.