基于同轴聚焦微流控拓扑构造的双乳液滴生成机制数值模拟  

Numerical Simulation of Double Emulsion Droplet Generation Mechanism Based on Coaxial Focusing Microfluidic Topological Configuration

作　　者：朱晓武 罗永皓 张伟业 刘文文[1] Zhu Xiaowu;Luo Yonghao;Zhang Weiye;Liu Wenwen(College of Mechanical and Electrical Engineering,Wenzhou University,Wenzhou 325035,China;Institute of New Materials,Guangdong Academy of Sciences,Guangzhou 510651,China)

机构地区：[1]温州大学机电工程学院,浙江温州325035 [2]广东省科学院新材料研究所,广州510651

出　　处：《微纳电子技术》2024年第10期177-188,共12页Micronanoelectronic Technology

基　　金：国家重点研发项目(2022YFC2406);广东省科学院发展专项(2022GDASZH-2022010107);广东省特支计划(2019BT02C629);广州市科技局项目(202007020008)。

摘　　要：采用流体体积(VOF)相界面追踪技术建立了同轴聚焦微通道内双乳液滴生成过程的数值计算模型。当内相、中间相和外相流体流速分别为0.01、0.011、0.04m/s时,该模型能够稳定形成单分散性较好、直径为500μm的双乳液滴。形成的双乳液滴适合药物领域的应用。在此基础上,分析了聚焦孔半径、聚焦孔颈长与聚焦孔颈角对三相流体的液滴驱动方式的影响,并讨论了微流道拓扑结构变化与双乳液滴生成机制及特性的内在联系与机理。结果表明,聚焦孔半径影响了Marangoni效应对内液滴局部扰动的程度,在改变生成液滴截面尺寸的同时,也使液滴生成频率发生相应的变化。聚焦孔颈长的改变决定了内外相流体的流型,限制了液膜断裂与脱离过程,从而对液滴生成方式产生根本性影响。聚焦孔颈角的变化影响了鞘液对外界面的剪切作用,通常情况下较大的角度使得局部流体阻力得以缓慢的释放,有利于生成液滴界面的稳定性。The numerical computational model for the generation process of double emulsion droplets in a coaxial focusing microchannel was developed by the volume of fluid(VOF)phase interface tracing technology.When the flow velocities of inner phase,intermediate phase and outer phase fluids are 0.01,0.011 and 0.04 m/s respectively,the double emulsion droplets with good monodispersity and diameter of 500μm can be stably formed by the model.The formed double emulsion droplets are suitable for drug field application.On this basis,the effects of focusing aperture radius,focusing aperture neck length and focusing aperture neck angle on the droplet driving mode of the three-phase fluid were analyzed,and the intrinsic connection and mechanism of the microfluidic channel topology change with the mechanism and characteristics of the double emulsion droplet generation were discussed.The results show that the focusing aperture radius influences the degree of the local perturbation of the inner droplets by the Marangoni effect,which changes the droplet generation frequency while changing the crosssectional size of the generated droplets.The change of the focusing aperture neck length determines the flow patterns of the inner phase and outer phase fluids,limiting the liquid film fracture and detachment process,thus fundamentally affecting the droplet generation mode.The change of the focusing aperture neck angle affects the shear effect of the sheath fluid on the external interface,and a larger angle usually allows a slow release of the local fluid resistance,which is conducive to the stability of the interface of the generated droplets.

关 键 词：液滴微流控 双乳液滴 同轴聚焦结构 相界面追踪法 多相流 

分 类 号：O359[理学—流体力学]