The Study Of Segregation And Mixing Of Granular Material In Different Mixer

Granular matter is ubiquitous in our daily life. Due to its’ complexity, people do not clearly understand its’ dynamical character. We still cannot theoretically interpret the segregation and mixing of different particles in the drum, and the Brazil Nut Effect, Sandwich-like segregation and granular patterns in vibrated granular materials bed, while all of these phenomena often appear in the fields like agriculture, mine industry, pharmacy and so on. So the research of granular materials turns out to be very important.The segregation and mixing of granular materials in rotating mixer with circular and noncircular cross-sections are experimentally and theoretically studied. Filling condition and angular speed of mixers mainly impact granular segregation patterns in the circular mixer. When filling condition is constant, with the angular speed increasing, the segregation of granular materials becomes more obvious; if the angular speed reaches to the critical value, the segregation of granular materials will be broken. When the angular speed is constant, with the fill rate decreasing, the segregation of granular materials becomes more obvious. It is found that the geometry, filling condition and angular speed of mixers impact granular segregation patterns in the rotating mixer with noncircular cross-sections. Comparing the phenomena of granular flow in square with that in ellipse mixer, we find that the mid-layer thickness of flowing particles varies discontinuously in square mixer while continuously in ellipse mixer. We consider one particle’s motion in two mixers and the trajectories of the particle are completely different in mixing region which locates in bottom flow. Finally, we introduce segregation index to characterizing the transient state of segregation patterns in these two mixers.