Dramatic change of the self-diffusions of colloidal ellipsoids by hydrodynamic interactions in narrow channels  

作　　者：Han-Hai Li Zhong-Yu Zheng Tian Xie Yu-Ren Wang 李瀚海;郑中玉;谢天;王育人(National Microgravity Laboratory, Institute of Mechanics, Chinese Academy of Sciences, Beijing 100190, China;School of Engineering Sciences, University of Chinese Academy of Sciences, Beijing 100049, China)

机构地区：[1]National Microgravity Laboratory, Institute of Mechanics, Chinese Academy of Sciences, Beijing 100190, China [2]School of Engineering Sciences, University of Chinese Academy of Sciences, Beijing 100049, China

出　　处：《Chinese Physics B》2019年第7期293-298,共6页中国物理B（英文版）

基　　金：Project supported by the National Natural Science Foundation of China(Grants Nos.U1738118 and 11372314);the Strategic Priority Research Program on Space Science,the Chinese Academy of Sciences(A)(Grant Nos.XDA04020202 and XDA04020406);the Strategic Priority Research Program of the Chinese Academy of Sciences(Grant No.XDB22040301)

摘　　要：The self-diffusion problem of Brownian particles under the constraint of quasi-one-dimensional(q1 D) channel has raised wide concern.The hydrodynamic interaction(HI) plays an important role in many practical problems and two-body interactions remain dominant under q1D constraint.We measure the diffusion coefficient of individual ellipsoid when two ellipsoidal particles are close to each other by video-microscopy measurement.Meanwhile, we obtain the numerical simulation results of diffusion coefficient using finite element software.We find that the self-diffusion coefficient of the ellipsoid decreases exponentially with the decrease of their mutual distance X when X < X0, where X0 is the maximum distance of the ellipsoids to maintain their mutual influence, X0 and the variation rate are related to the aspect ratio p = a/b.The mean squared displacement(MSD) of the ellipsoids indicates that the self-diffusion appears as a crossover region, in which the diffusion coefficient increases as the time increases in the intermediate time regime, which is proven to be caused by the spatial variations affected by the hydrodynamic interactions.These findings indicate that hydrodynamic interaction can significantly affect the self-diffusion behavior of adjacent particles and has important implications to the research of microfluidic problems in blood vessels and bones, drug delivery, and lab-on-chip.The self-diffusion problem of Brownian particles under the constraint of quasi-one-dimensional（q1 D） channel has raised wide concern.The hydrodynamic interaction（HI） plays an important role in many practical problems and two-body interactions remain dominant under q1D constraint.We measure the diffusion coefficient of individual ellipsoid when two ellipsoidal particles are close to each other by video-microscopy measurement.Meanwhile, we obtain the numerical simulation results of diffusion coefficient using finite element software.We find that the self-diffusion coefficient of the ellipsoid decreases exponentially with the decrease of their mutual distance X when X < X0, where X0 is the maximum distance of the ellipsoids to maintain their mutual influence, X0 and the variation rate are related to the aspect ratio p = a/b.The mean squared displacement（MSD） of the ellipsoids indicates that the self-diffusion appears as a crossover region, in which the diffusion coefficient increases as the time increases in the intermediate time regime, which is proven to be caused by the spatial variations affected by the hydrodynamic interactions.These findings indicate that hydrodynamic interaction can significantly affect the self-diffusion behavior of adjacent particles and has important implications to the research of microfluidic problems in blood vessels and bones, drug delivery, and lab-on-chip.

关 键 词：HYDRODYNAMIC interaction SELF-DIFFUSION ELLIPSOIDS channel 

分 类 号：O4[理学—物理]