摘要
研究颗粒体系中的结构与缺陷对于研究固-液融化的物理机制具有重要的价值.本文实验研究了垂直振动下单层湿颗粒在固-液融化过程中的结构与缺陷.根据实验及理论分析构建了湿颗粒体系的接触模型,量化了准二维湿颗粒体系融化过程中颗粒的结构变化.然后以颗粒为点建立Voronoi图对颗粒体系的"相"转变进行研究,并引入了局部体积分数来确定融化过程中缺陷变化的临界状态.实验结果表明,颗粒系统在团簇的边缘开始发生缺陷,并呈现链状的缺陷对向中心蔓延的现象.并且,颗粒发生缺陷时七相缺陷颗粒的局部体积分数显著减小,明显小于五相缺陷和六角相颗粒的局部体积分数.对局部体积分数的分析表明,当最小局部体积分数φ≤0.6652时发生缺陷,当φ≤0.4872时颗粒系统发生从固体到液体的转变.
The study of structural defects in particle systems is of great value for studying solid-liquid melting.The volume fraction is a key parameter that can be used to accurately quantify the phase-transition process.The collective behavior and interaction form in a wet particle system are much more complex than that of a dry particle material because of the existence of liquid bridge force between the wet particles.In this paper,the structural defects and the critical value of solid-liquid transformation in the monolayer wet particles during solid-liquid melting under vertical vibration are experimentally studied.The contact model of the wet particle system is constructed according to experimental and theoretical analysis,and the structural changes of the particles in the melting process of the quasi-two-dimensional wet particle system are quantified.The Voronoi tessellation is established to study the phase transition of the particle system,and the local volume fraction is adopted to determine the state of structural defect change during melting.The experimental results indicate that the phase-transition process is caused by structural defects in the solid.The defects appear from the edge of the particle system,and the chain defect pairs spread to the center.The reason for structural defects at the edge of the cluster is that the particles at the edge of the cluster are subjected to less liquid bridge force,and the kinetic energy brought by the collision between the particles and the bottom wall makes the particles become active and begin to explore the available space.The chain defects are caused by the force chain generated by the fluid bridge force,which makes the particles tend to move together in rows.In addition,the local volume fraction of seven-phase defective particles decreases significantly and is much smaller than that of five-phase defective particles and six-phase defective particles when defects occur.Therefore,the evolution and the critical state of the structural defects can be quantified by measuri
作者
王蓬
孔平
李然
华云松
厚美瑛
孙其诚
Wang Peng;Kong Ping;Li Ran;Hua Yun-Song;Hou Mei-Ying;Sun Qi-Cheng(School of Medical Instrument and Food Engineering,University of Shanghai for Science and Technology,Shanghai 200093,China;Shanghai Key Laboratory of Molecular Imaging,Shanghai University of Medicine and Health Sciences,Shanghai 201318,China;School of Optical-Electrical and Computer Engineering,University of Shanghai for Science and Technology,Shanghai 215300,China;Institute of Physics Chinese Academy of Sciences,Beijing 100190,China;School of Civil Engineering,Tsinghua University,Beijing 100084,China)
出处
《物理学报》
SCIE
EI
CAS
CSCD
北大核心
2021年第11期239-247,共9页
Acta Physica Sinica
基金
国家自然科学基金(批准号:11902190,91634202,12072200,12002213)
上海市自然科学基金(批准号:20ZR1438800)
上海市分子影像学重点实验室建设项目(批准号:18DZ2260400)
上海市教育委员会高峰高原学科建设计划(SUMHS医学技术Ⅱ类高原学科建设计划,2018—2020年)资助的课题。
关键词
固-液融化
缺陷
湿颗粒
局部体积分数
solid-liquid melting
defect
wet particles
local volume fraction
