How to ignore collision of one kind of particles while retaining the collision of another kind of particles

MFiX How to
#1

There are two solid phase. One is dominating and another is minor. So I whant to ignore the collison of the secondary particle while retaining the collision of the primiary particle. I need to modify the code of Mfix. How can I do this?

#2

If you are using DEM, I do not suggest to do so, because if you do not consider the collision between particles, unphysical large overlap can happen. You can try the hybrid model (TFM+DEM) or PIC for both solids.

#4

Have you figure out a feasible way to implement this idea in MFIX？