TY - JOUR
T1 - Transport dynamics of complex fluids
AU - Song, Sanggeun
AU - Park, Seong Jun
AU - Kim, Minjung
AU - Kim, Jun Soo
AU - Sung, Bong June
AU - Lee, Sangyoub
AU - Kim, Ji Hyun
AU - Sung, Jaeyoung
N1 - Funding Information:
ACKNOWLEDGMENTS. We gratefully acknowledge Professors Mike Shlesinger, Eli Barkai, Ralf Metzler, YounJoon Jung, and Jae-Hyung Jeon for their helpful comments and Mr. Luke Bates for his careful reading of our manuscript. This work was supported by the Creative Research Initiative Project program (2015R1A3A2066497) and the National Research Foundation of Korea Grant (2015R1A2A1A15055664) funded by the Korean government. S.S. also acknowledges the Chung-Ang University Graduate Research Scholarship in 2016.
Publisher Copyright:
© 2019 National Academy of Sciences. All rights reserved.
PY - 2019
Y1 - 2019
N2 - Thermal motion in complex fluids is a complicated stochastic process but ubiquitously exhibits initial ballistic, intermediate subdiffusive, and long-time diffusive motion, unless interrupted. Despite its relevance to numerous dynamical processes of interest in modern science, a unified, quantitative understanding of thermal motion in complex fluids remains a challenging problem. Here, we present a transport equation and its solutions, which yield a unified quantitative explanation of the mean-square displacement (MSD), the non-Gaussian parameter (NGP), and the displacement distribution of complex fluids. In our approach, the environment-coupled diffusion kernel and its time correlation function (TCF) are the essential quantities that determine transport dynamics and characterize mobility fluctuation of complex fluids; their time profiles are directly extractable from a model-free analysis of the MSD and NGP or, with greater computational expense, from the two-point and four-point velocity autocorrelation functions. We construct a general, explicit model of the diffusion kernel, comprising one unbound-mode and multiple bound-mode components, which provides an excellent approximate description of transport dynamics of various complex fluidic systems such as supercooled water, colloidal beads diffusing on lipid tubes, and dense hard disk fluid. We also introduce the concepts of intrinsic disorder and extrinsic disorder that have distinct effects on transport dynamics and different dependencies on temperature and density. This work presents an unexplored direction for quantitative understanding of transport and transport-coupled processes in complex disordered media.
AB - Thermal motion in complex fluids is a complicated stochastic process but ubiquitously exhibits initial ballistic, intermediate subdiffusive, and long-time diffusive motion, unless interrupted. Despite its relevance to numerous dynamical processes of interest in modern science, a unified, quantitative understanding of thermal motion in complex fluids remains a challenging problem. Here, we present a transport equation and its solutions, which yield a unified quantitative explanation of the mean-square displacement (MSD), the non-Gaussian parameter (NGP), and the displacement distribution of complex fluids. In our approach, the environment-coupled diffusion kernel and its time correlation function (TCF) are the essential quantities that determine transport dynamics and characterize mobility fluctuation of complex fluids; their time profiles are directly extractable from a model-free analysis of the MSD and NGP or, with greater computational expense, from the two-point and four-point velocity autocorrelation functions. We construct a general, explicit model of the diffusion kernel, comprising one unbound-mode and multiple bound-mode components, which provides an excellent approximate description of transport dynamics of various complex fluidic systems such as supercooled water, colloidal beads diffusing on lipid tubes, and dense hard disk fluid. We also introduce the concepts of intrinsic disorder and extrinsic disorder that have distinct effects on transport dynamics and different dependencies on temperature and density. This work presents an unexplored direction for quantitative understanding of transport and transport-coupled processes in complex disordered media.
KW - Colloidal particles on lipid tube
KW - Complex fluids
KW - Diffusion kernel correlation
KW - Supercooled
KW - Thermal motion
KW - Water
UR - http://www.scopus.com/inward/record.url?scp=85068135891&partnerID=8YFLogxK
U2 - 10.1073/pnas.1900239116
DO - 10.1073/pnas.1900239116
M3 - Article
C2 - 31175151
AN - SCOPUS:85068135891
SN - 0027-8424
VL - 116
SP - 12733
EP - 12742
JO - Proceedings of the National Academy of Sciences of the United States of America
JF - Proceedings of the National Academy of Sciences of the United States of America
IS - 26
ER -