We investigate the underlying mechanism of capillary force balance at the contact line. In particular, we offer a novel approach to describe and quantify the capillary force on the liquid in coexistence with its vapor phase, which is crucial in wetting and spreading dynamics. Its relation with the interface tension is elucidated. The proposed model is verified by our molecular dynamics simulations over a wide contact angle range. Differences in capillary forces are observed in evaporating droplets on homogeneous and decorated surfaces. Our findings not only provide a theoretical insight into capillary forces at the contact line, but also validate Young’s equation based on a mechanical interpretation.

中文翻译：

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接触线处毛细管力平衡的微观起源

我们研究了接触线处毛细力平衡的潜在机理。特别是，我们提供了一种新颖的方法来描述和量化与液相共存的液体上的毛细管力，这对于润湿和扩散动力学至关重要。阐明了其与界面张力的关系。我们的分子动力学模拟在较宽的接触角范围内对提出的模型进行了验证。在均匀且装饰的表面上蒸发的液滴中观察到毛细管力的差异。我们的发现不仅为接触线的毛细作用力提供了理论上的见解，而且还基于机械解释验证了杨氏方程。