The dynamic wetting of mixture droplets on the solid surface is important for various industrial technologies and applications, such as evaporation, microfluidics, surface self-cleaning, and power cycling. Due to the influence of different components, the dynamic wetting process of mixture droplets is quite different from that of pure fluids. Currently, the understanding of the spreading mechanism of mixture droplets is lacking. In this paper, molecular dynamics simulation is used to study the dynamic spreading process of ethanol/water and difluoromethane (R32)/2,3,3,3-tetrafluoroprop-1-ene (R1234yf) mixture droplets on a smooth and homogeneous surface. The droplets have different component mole fractions and various diameters of 9.4–12.8 nm. The influences of the component mole fraction on the spreading radius and dynamic contact angle are analyzed and compared with molecular kinetic theory. It is found that for the R32/R1234yf mixture droplets, the component mole fractions in the bulk and at the interface of the droplet are close and the dynamic spreading process is similar to that of pure fluids. However, for the ethanol/water mixture droplets, the mole fraction of ethanol is higher at the vapor–liquid and solid–liquid interfaces than in the bulk, and the spreading is faster than that of pure fluids. The mole fraction and the physical properties in the triple contact region are analyzed, and an improved prediction is proposed for the moving velocity of the triple contact line and the spreading process of the mixture droplet.

中文翻译：

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混合纳米液滴在光滑均匀表面上扩散的分子动力学模拟

混合液滴在固体表面上的动态润湿对于各种工业技术和应用至关重要，例如蒸发，微流体，表面自清洁和功率循环。由于不同组分的影响，混合液滴的动态润湿过程与纯流体的完全不同。当前，对混合物液滴的扩散机理缺乏了解。本文使用分子动力学模拟研究了乙醇/水和二氟甲烷（R32）/ 2,3,3,3-四氟丙-1-烯（R1234yf）混合液滴在光滑均匀表面上的动态扩散过程。液滴具有不同的组分摩尔分数和9.4-12.8 nm的各种直径。分析了组分摩尔分数对扩散半径和动态接触角的影响，并与分子动力学理论进行了比较。发现对于R32 / R1234yf混合液滴，在主体中和在液滴的界面处的组分摩尔分数是接近的，并且动态扩散过程类似于纯流体。但是，对于乙醇/水混合物液滴，乙醇在气-液和固-液界面处的摩尔分数要比在大体积中要高，并且其扩散比纯流体的扩散要快。分析了三重接触区域的摩尔分数和物理性质，并提出了改进的三重接触线移动速度和混合液滴扩散过程的预测方法。发现对于R32 / R1234yf混合液滴，在主体中和在液滴的界面处的组分摩尔分数是接近的，并且动态扩散过程类似于纯流体。但是，对于乙醇/水混合物液滴，乙醇在气-液和固-液界面处的摩尔分数要比在大体积中要高，并且其扩散比纯流体的扩散要快。分析了三重接触区的摩尔分数和物理性质，并提出了改进的三重接触线移动速度和混合液滴扩散过程的预测方法。发现对于R32 / R1234yf混合液滴，在主体中和在液滴的界面处的组分摩尔分数是接近的，并且动态扩散过程类似于纯流体。但是，对于乙醇/水混合物液滴，乙醇在气-液和固-液界面处的摩尔分数要比在大体积中要高，并且其扩散比纯流体的扩散要快。分析了三重接触区域的摩尔分数和物理性质，并提出了改进的三重接触线移动速度和混合液滴扩散过程的预测方法。对于乙醇/水混合液滴，乙醇在气-液和固-液界面处的摩尔分数要比在大体积中高，并且其扩散比纯流体的扩散要快。分析了三重接触区的摩尔分数和物理性质，并提出了改进的三重接触线移动速度和混合液滴扩散过程的预测方法。对于乙醇/水混合液滴，乙醇在气-液和固-液界面处的摩尔分数要比在大体积中高，并且其扩散比纯流体的扩散要快。分析了三重接触区域的摩尔分数和物理性质，并提出了改进的三重接触线移动速度和混合液滴扩散过程的预测方法。