Intruder Motion In Two-dimensional Shaken Granular Beds

Granular segregation has a strong value in the fields of academic and practical application,commonly the segregation have Brazil nut effect, reverse Brazil nut effect，sandwich patternand other well-known phenomena. This paper mainly introduces the segregation of the intruderin the granular beds. Nowadays, there have been many multitudinous theoretical andsimulative work focused on the intruder dynamics, and summarized several factors, namelysize ratio, density ratio, vibrational condition, interstitial medium, and convection, as mainmechanisms responsible for the rising or the sinking behavior of an intruder in a granular bed.However, few investigations have directly explored the motion of intruders in various granularbeds when the five mechanisms are fixed, which could provide an experimental aid for theestablishment of future theories.With the vertical vibrationconditions, we studied the motion of an intruder in two-dimensional granular beds. Five kinds of particle materials with different size and density areexperimentally investigated. We drew the experimentalf Γphase diagrams of variouscombinations of the materials which based on all records of the experimental phenomena andshowed the trajectories of the intruders. According to the experiment we concluded that, it isfound that even with same size and density ratio of the intruder to the background particles, theintruder exhibits a distinct behavior at given vibrational conditions: rising behavior in the woodcylinder granular bed, sinking behavior in others’ granular bed. We slightly tune the size anddensity ratio to confirm the reliability of the experimental results. In addition, we examine theinfluences of interstitial air, convection and the initial position on the intruder’s motion,speculating that the opposite motion could be traced to the material properties of thebackground particles.