相场格子Boltzmann方法模拟载表面活性剂液滴的剪切动态行为  

Phase-field lattice Boltzmann method simulation of shear dynamic behavior of surfactant-laden droplets

作　　者：陈涛 姚丽萍[1] 张良奇[2] 曾忠[2] 谢守勇[1] CHEN Tao;YAO Liping;ZHANG Liangqi;ZENG Zhong;XIE Shouyong(College of Engineering and Technology,Southwest University,Chongqing 400715,P.R.China;College of Aerospace Engineering,Chongqing University,Chongqing 400044,P.R.China)

机构地区：[1]西南大学工程技术学院,重庆400715 [2]重庆大学航空航天学院,重庆400044

出　　处：《重庆大学学报》2025年第4期12-28,共17页Journal of Chongqing University

基　　金：国家自然科学基金(12172070,12102071);重庆市科技局直通车项目(CSTB2022BSXM-JCX0086)。

摘　　要：表面活性剂可以降低流体界面的表面张力,显著改变固体表面的润湿特性,在工业生产中被广泛使用。为探究载表面活性剂液滴在固体表面上的运动特性,基于Cahn-Hilliard相场格子玻尔兹曼方法,引入由实验得出的考虑三相接触线移动速度的Yokoi动态接触角模型,建立了一种考虑可溶性表面活性剂流动的移动接触线模型。根据控制方程独立开发计算程序,并采用并行化处理提高计算效率。在此基础上,研究了线性剪切作用下液滴的动态过程,分析了有效毛细数Ca_(e)和固体表面润湿性对纯净液滴和载表面活性剂液滴变形的影响规律。结果表明:有效毛细数Ca_(e)增大会促进液滴变形,当其增大到一定程度时液滴会产生破裂,载表面活性剂液滴相对于纯净液滴有更大的变形量和移动速度。当液滴附着于亲水性固体表面时,在相同剪切作用下,载活性剂液滴相对于纯净液滴有更长的相对弧长和相对润湿长度;且液滴在亲水表面比其在中性表面变形的相对弧长和相对润湿长度值亦更大。而当液滴附着于疏水性固体表面时,液滴则会在剪切作用下脱离固体表面;在相同的毛细数下,载表面活性剂液滴相对于纯净液滴先脱离固体表面且移动速度更快。研究结果表明可溶性表面活性剂的存在会对液滴剪切运动和变形产生较大影响,可以促进液滴变形,增大液滴移动速度。本文的数值方法可用于计算载有可溶性活性剂液滴的移动接触线问题。Surfactants can reduce fluid interface tension and significantly alter the wetting properties of solid surfaces,making them essential in various industrial applications.To investigate the motion characteristics of surfactant-laden droplets on solid surfaces,a coupled model incorporating soluble surfactant flow and contact line dynamics was established using the Cahn-Hilliard phase field lattice Boltzmann method,alongside the Yokoi dynamic contact angle model considering the velocity of the three-phase contact line based on experimental data.A computational program was independently developed and optimized with parallel processing to improve computational efficiency.Subsequently,the dynamic behavior of droplets under linear shear flow was studied,focusing on the influence of the effective capillary number(Ca_(e))and surface wettability on the deformation of both clean and surfactant-laden droplets.The results show that an increase in the effective capillary number(Ca_(e))promotes droplet deformation,but beyond a critical threshold,the droplet ruptures.Surfactant-laden droplets exhibit greater deformation and faster movement compared to pure droplets.On hydrophilic surfaces,droplets elongate further under shear,with surfactant-laden droplets exhibiting longer relative arc and wetting length than their pure counterparts.Conversely,on hydrophobic surfaces,droplets tend to detach under shear,with surfactantladen droplets detaching earlier than pure droplets.These findings indicate that soluble surfactants significantly impact droplet shear dynamics by promoting deformation and increasing movement speed.The numerical methods presented in this study offer a robust approach for simulating moving contact line problems in droplets containing soluble surfactants.

关 键 词：相场法 格子玻尔兹曼方法 可溶性表面活性剂 剪切 液滴 

分 类 号：O359.1[理学—流体力学]