Intruder trajectory tracking in a three-dimensional vibration-driven granular system:Unveiling the mechanism of the Brazil nut effect  

作　　者：李拓 程可 彭政 杨晖 厚美瑛 Tuo Li;Ke Cheng;Zheng Peng;Hui Yang;Meiying Hou(School of Optical-Electrical and Computer Engineering,University of Shanghai for Science and Technology,Shanghai 200093,China;Soft Matter Laboratory,Institute of Physics,Chinese Academy of Sciences,Beijing 100190,China;School of Physics,Central South University,Changsha 410012,China;College of Medical Instrumentation,Shanghai University of Medicine&Health Sciences,Shanghai 201318,China)

机构地区：[1]School of Optical-Electrical and Computer Engineering,University of Shanghai for Science and Technology,Shanghai 200093,China [2]Soft Matter Laboratory,Institute of Physics,Chinese Academy of Sciences,Beijing 100190,China [3]School of Physics,Central South University,Changsha 410012,China [4]College of Medical Instrumentation,Shanghai University of Medicine&Health Sciences,Shanghai 201318,China

出　　处：《Chinese Physics B》2023年第10期106-111,共6页中国物理B（英文版）

基　　金：Project supported by the Space Application System of China Manned Space Program;the National Natural Science Foundation of China(Grant Nos.12072200 and 12002213)。

摘　　要：We employ a Hall-effect magnetic sensor array to accurately track the trajectory of a single magnetic sphere,referred to as the“intruder,”within a three-dimensional vibro-fluidized granular bed to unravel the underlying physical mechanism governing the motion of the intruder.Within the acceleration range of 3.5 g≥Γ≥1.5 g,we find that,regardless of the intruder's initial position,it consistently reaches the same equilibrium depth when the vibration acceleration(Γ)and frequency(ω)are fixed.ForΓ≤2.5 g,the equilibrium position lies on the surface of the granular bed,while forΓ>2.5 g,it shifts below the surface.Additionally,intruders with different densities exhibit varying equilibrium depths,with higher density resulting in a deeper equilibrium position.To understand the mechanism behind the intruder's upward or downward motion,we measure its rising or sinking velocities under different vibration parameters.Our findings demonstrate that the rising velocity of the intruder,under varying vibration accelerations(Γ)and frequencies(ω),can be collapsed using the ratioΓ/ω,while the sinking velocity remains unaffected by the vibration strength.This confirms that the upward motion of the larger sphere,associated with the Brazil nut effect,primarily arises from the void-filling mechanism of the bed particles.Furthermore,our experiments reveal that the presence of convection within the bed particles has minimal impact on the motion of the intruder.

关 键 词：granular matter SEGREGATION Brazil nut effect vibro-fluidization 

分 类 号：O469[理学—凝聚态物理]