Analysis of collisions of solid bidispersed particles during their gravitational sedimentation

The process of the collision of bidispersed particles having different sizes and (or) densities during their motion in the field of the gravity force has been analyzed. A dimensionless criterion (the collision Stokes number) has been proposed that accounts for the presence and intensity of the particle-particle collisions. This criterion has been experimentally tested for the case of the sedimentation of a bidispersed mixture of iron and glass particles in the motionless air in a pipe.