活性流体中被动粒子扩散行为的模拟研究  

Simulation of Passive Particles Diffusion Behavior in Active Fluids

作　　者：许晓飞[1] 张达[1] 程阳 刘凤霞[1] 魏炜[1] 刘志军[1] XU Xiao-Fei;ZHANG Da;CHENG Yang;LIU Feng-Xia;WEI Wei;LIU Zhi-Jun(Research&Design Institute of Fluid and Powder Engineering,Dalian University of Technology,Dalian 116024,China)

机构地区：[1]大连理工大学流体与粉体工程研究设计所,大连116024

出　　处：《工程热物理学报》2022年第4期1041-1047,共7页Journal of Engineering Thermophysics

基　　金：国家自然科学基金(No.51876030);中央高校基本科研业务费(No.DUT19JC60)。

摘　　要：通过拓展朗之万方程实现活性粒子运动的模拟,建立被动粒子和活性粒子的共混体系,研究被动粒子在活性流体中的扩散行为。通过计算被动粒子的均方位移确定扩散系数,考察活性粒子浓度、自驱动速度和被动粒子粒径对被动粒子扩散行为的影响规律。结果表明,活性流体中被动粒子的扩散系数随自身粒径的增大而减小;提高活性粒子的浓度和自驱动速度均能显著强化被动粒子的扩散。浸没在活性流体中的被动粒子的扩散行为初期表现为次扩散,之后转化为超扩散。活性流体体系的有效温度随活性流体浓度的增加和被动粒子粒径的增大而升高,被动粒子相当于浸没在更高温度的常规流体中。By extending Langevin equation to simulate the motion of active particles, a blend system of passive particles and active particles was established to study the diffusion behavior of passive particles in active fluids. The diffusion coefficient is determined by calculating the mean square displacement of the passive particles. Effect of active particle concentration, self–propelling speed and passive particle size on the diffusion behavior of passive particle is investigated. The results show that the diffusion coefficient of passive particles in active fluids decreases with the increase of their own particle size. The diffusion of passive particles can be significantly enhanced by increasing the concentration and self–propelling speed of active particles. The diffusion behavior of passive particles immersed in the active fluid behaves as sub–diffusion in the initial stage, and then transforms into super–diffusion. The effective temperature of active fluid system increases with the increase of active fluid concentration and the passive particle size, which is equivalent to the passive particles being immersed in a higher temperature fluid.

关 键 词：活性流体 朗之万方程 布朗动力学模拟 扩散行为 有效温度 

分 类 号：TQ021.4[化学工程]