(78a) Numerical Study of Vibration Induced Segregation with Ellipsoids

Segregation in granular systems is primarily a practical concern of many industries. A better understanding of segregation will help solve the handling and processing of these industrial issues. Among all processes that may cause segregation, vibration can drive large particles to move upward within bulk solids of small particles. This phenomenon has been well studied considering various particle properties, but a comprehensive understanding of the influence of particle shape is still not well addressed in the literature. In this work, different vibrated binary systems of ellipsoidal particles are investigated based on DEM simulation. The binary granular materials are charged into the vessels separately, and vibrations are introduced after all particles settle down. Aspect ratio of ellipsoids is used to quantitatively determine the particle shape. Other factors including vibration amplitudes, frequencies and size ratio are also tested. Results have shown that this model can generate the Brazil Nut Effect, and vibration conditions are the triggering factors of the segregation while size ratio and aspect ratio affect the segregation degree. The effects of particle shape on segregation can be explained by its influence on the particles movement. As packing density and coordination number are strongly dependent on particle shape, aspect ratio will in turn affect the particles’ void-filling behaviors which further affect the segregation phenomena.