Study of the Dynamics and Segregation Mechanism of Granular Materials(2/3)

The mixing/segregation behavior of granular flow is a very important research topic, and it is also a critical issue in many industrial applications and needs to be solved. Although this phenomenon is very intuitive, the physics and mechanisms are very complicated. Therefore, there are many issues still need to be clarified, and it is necessary to conduct the experimental measurements and theoretical predictions for further investigations. In addition, in a granular system, when different-properties particles are under different carried vehicles and different driving forces, the segregation mechanisms are also different. Therefore, this project will conduct a three-year study on the segregation and mixing behavior of powders/particles. The first year of the project will conduct experimentally studies on the granular size segregations in a double-walled rotating drum. The effect of filling degree and rotation speeds of the rotating drum are discussed in this year. The results in this year can help us understand the physical mechanism and the principle of particle segregation phenomenon when the system in an almost fully filled. The influences of gravitational and centrifugal forces on the segregation in this system will also be discussed. The second year of the project will discuss the effect of the content of fine powders on the collapse behavior of large particles by conducting a series of granular collapse experiments. Due to the simple setup and rich behavior, the granular column collapse has been studied experimentally and numerically by several authors. However, the lubricate effect of fine powder on such granular collapse has received relatively less attention and remains an issue worthy of examination. Therefore, this issue will be investigated in-depth in this year. The third year of the project will investigate the effect of granular size segregation in a vibrating bed. The size segregation phenomenon under the Brazil nut effect will be discussed by immersing a large-sized particle (intruder) in to a small-sized-particle vibrating bed system. The rising time of the large-sized particle will also be measured and analyzed to quantify the strength of the segregation.