Droplet-based microfluidics technologies hold great attention in a wide range of applications, including chemical analysis, drug screening, and food industries. This work aimed to describe the effects of different physical properties of the two immiscible phases on droplet formation in a flow-focusing microfluidic device and determining proper flow rates to form a droplet within the desired size range. A numerical model was developed to solve the governing equations of two-phase flow and the results were validated with previous experimental results. The results demonstrate different types of droplet formation regimes from dripping to jetting and different production rates of droplets as a consequence of the impact of each property on fluid flow, including the viscosity ratio, density, interfacial tension, and the flow rate ratio. Based on the results, flow rate, viscosity, and interfacial tension strongly affect the droplet formation regime as well as its size and shape. Droplet diameter increases by increasing the dispersed to continuous phase flow rate as well as the interfacial tension while it decreases by increasing the viscosity ratio and the continuous phase density. Moreover, the formation of satellite droplets was modeled, and the effect of interfacial tension, the viscosity of the dispersed phase and the continuous phase density were found to be important on the conditions that the satellite droplets are suppressed. Since the formation of the satellite droplets induces polydispersity in droplet size, this phenomenon is avoided. Collectively, choosing appropriate aqueous and oil phases with proper physical properties is crucial in forming monodisperse droplets with defined size and shape.

中文翻译：

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微流体装置内液滴形成和特性的参数研究——案例研究

基于液滴的微流控技术在化学分析、药物筛选和食品工业等广泛应用中受到广泛关注。这项工作旨在描述两种不混溶相的不同物理性质对流动聚焦微流体装置中液滴形成的影响，并确定适当的流速以形成所需尺寸范围内的液滴。建立了一个数值模型来求解两相流的控制方程，并与之前的实验结果进行了验证。结果表明，由于每种特性对流体流动的影响，包括粘度比、密度、界面张力和流速比，从滴落到喷射的不同类型的液滴形成方式和不同的液滴产生速率。根据结果​​，流速、粘度和界面张力强烈影响液滴的形成方式及其大小和形状。液滴直径通过增加分散相到连续相的流速以及界面张力而增加，而通过增加粘度比和连续相密度而减小。此外，对卫星液滴的形成进行了建模，发现界面张力、分散相粘度和连续相密度对卫星液滴被抑制的条件很重要。由于卫星液滴的形成导致液滴尺寸的多分散性，因此可以避免这种现象。集体，