121st General Meeting of the KCS

Type Poster Presentation
Area Physical Chemistry
Room No. Event Hall
Time 4월 20일 (금요일) 11:00~12:30
Code PHYS.P-155
Subject Universal Transport Dynamics of Complex Fluids: Effects of Intrinsic and Extrinsic Disorder
Authors Sanggeun Song, Seong-jun Park, Bong June Sung1, Jun Soo Kim2, Ji-Hyun Kim*, Jaeyoung Sung*
Department of Chemistry, Chung-Ang University, Korea
1Department of Chemistry, Sogang University, Korea
2Department of Chemistry and Nanoscience, Ewha Womans University, Korea
Abstract We present a general theory of thermal motion in disordered fluids, introducing a new type of random walk model with a sojourn time distribution dependent on hidden dynamic variables. This model encompasses the well-known continuous-time random walk (CTRW) model and the more recent, stochastic diffusivity (SD) model. In the hydrodynamic limit, our model yields a new transport equation, which provides a unified, quantitative explanation of the anomalous transport dynamics commonly observed in various disordered fluids. We find that the long-time limit value of the product between the mean-square displacement (MSD) and the non-Gaussian parameter (NGP) serves as a useful measure of disorder. This measure is decomposable into extrinsic disorder, originating from environment-induced fluctuation in transport dynamics, and intrinsic disorder, originating from non-Fickian mean transport dynamics. Intrinsic disorder causes the MSD of disordered fluids to deviate from the prediction of the simple diffusion model or the SD model. Meanwhile, extrinsic noise causes the NGP of disordered fluids to deviate from the CTRW model’s prediction. By analyzing the MSD and NGP of supercooled water and dense hard-disc fluids, we find that extrinsic disorder is far more sensitive to temperature and density than intrinsic disorder. We also find that the NGP alone can serve as an ergodicity metric of transport systems; it vanishes for ergodic systems at long times, universally following inverse-time relaxation, but remains finite for non-ergodic systems. This work opens new doors for analytic analysis of transport and transport-coupled processes in complex disordered media, including living cells, by making the effects of complex hidden environments on transport dynamics analytically accessible.
E-mail ssk10042000@cau.ac.kr