论文标题
界面进化和液滴捏合机理的计算分析，两相液体流过T型微流体系统
Computational analysis of interface evolution and droplet pinch-off mechanism in two-phase liquid flow through T-junction microfluidic system
论文作者
论文摘要
这项工作探索了液滴形成的界面进化和通过跨流微流体设备的两相流中的捏合机理。二维数学模型方程已在挤压方面使用有限元方法（$ ca_c <10^{ - 2} $），用于宽的流量范围（$ QR = 0.1-10 $）和固定的触点角度（$θ= 135^o $）。液滴的形成过程已分为各种瞬时阶段，因为初始，填充，挤压，捏合和稳定的液滴通过相位剖面中界面演化的微观可视化。界面的动力学和两个阶段中的点压力得到了进一步的收获和讨论。连续相中的最大压力与QR线性变化。通过确定弯曲（$ r_ {c，min} $）的局部半径和颈部宽度（2R），已经彻底阐明了液滴捏合机构。在捏合点，$ r_ {c，min} $和2R都与QR无关。此外，通过分析拉普拉斯压力（$ p _ {\ text {l}} $）的界面拓扑动态，作用于界面曲率，使用（a）两个相的压力传感器在两个相的压力传感器中进行了评估，（b）局部曲率半径，曲率和（c）最小值的曲率半径。可以可靠地使用从本工作获得的见解来设计微流体设备的模型和原型，以在乳液中生成单分散的液滴，并且液滴分解机制将有助于准确预测捏合力矩。拟议的知识提供了接口演化和液滴捏的详细见解，可精确地达到10 $μ$ S的精度，分辨率为10 $μ$ m，相当于具有高速（$ 10^{5} $ fps）和高分辨率（10 $μ$ m $ m pixel Size）摄像机的实验流动可视化。
This work has explored interface evolution and pinch-off mechanism of the droplet formation in two-phase flow through cross-flow microfluidic device. The two-dimensional mathematical model equations have been solved using the finite element method under the squeezing regime ($Ca_c < 10^{-2}$) for wide range of flow rates ($Qr = 0.1 - 10$) and fixed contact angle ($θ=135^o$). The droplet formation process has been classified into various instantaneous stages as initial, filling, squeezing, pinch-off and stable droplet through microscopic visualization of interface evolution in phase profiles. The dynamics of interface, and point pressure in both phases is further gained and discussed. Maximum pressure in the continuous phase varied linearly with Qr. The droplet pinch-off mechanism has been thoroughly elucidated by determining the local radius of the curvature ($R_{c,min}$) and neck width (2r) during the squeezing and pinch-off stages. At the pinch-off point, both $R_{c,min}$ and 2r are non-linearly related to Qr. Further, the topological dynamics of interface has been explored by analyzing the Laplace pressure ($p_{\text{L}}$), acting on the interface curvature, evaluated using (a) pressure sensors in both phases, (b) local radius of curvature, and (c) minimum radius of curvature. The insights obtained from the present work can reliably be used in designing the model and prototypes of microfluidic devices for generating monodispersed droplets in emulsions, and the droplet breakup mechanism would help accurate prediction of the pinch-off moment. The proposed knowledge provides detailed insights of the interface evolution and droplet pinch-off to a precision of 10 $μ$s and resolution of 10 $μ$m, equivalent to experimental flow visualization with a high-speed ($10^{5}$ fps) and high-resolution (10 $μ$m pixel size) camera.
