微粗糙结构表面液滴浸润特性的多体耗散粒子动力学研究

超疏水表面因其优异的自洁作用一直是表面科学领域关注的重点.本文使用多体耗散粒子动力学(many-body dissipative particle dynamics, MDPD)方法模拟研究了不同粗糙结构下液滴的浸润特性, 并与Cassie-Baxter理论进行了对比. 研究使用了一种具有长吸短斥作用的流固作用函数来获得不同的液滴浸润性, 并利用一种简洁的数值方法来测量接触角. 模拟结果表明本研究方法能够稳定地捕捉到液滴在粗糙表面的静态和动态特性. 模拟了粗糙结构对三相接触线运动的黏滞作用, 与物理实验结果相符合, 表明Cassie-Baxter理论在实际应用中尚存在一定局限性. 研究分析了在动态铺展过程中的能量转化关系, 并指出在低值表面容易引起液滴反弹.

Drops on microstructured surfaces: A numerical study using many-body dissipative particle dynamics

Because of their ability of self-clean, superhydrophobic surfaces have received substantial attention for years especially in surface science field. In this paper, the drop's wettability on different rough surfaces is simulated by using many-body dissipative particle dynamics (MDPD) and a contrast with the Cassie-Baxter theory's predictions is made. A combination of short-range repulsive and long-range attractive forces is used as wall-fluid interaction to generate different wettability, and a simple but efficient numerical method is introduced to measure the contact angle. The simulation could capture the static and dynamic properties of drop on textured surfaces, it is also shown that the microstructured surfaces can pin the three-phase (solid-liquid-vapour) contact line and this phenomenon has also been observed by other researchers in their physical experiments, suggesting that people should be careful when using the Cassie-Baxter theory. An analysis was given about energy transformation between kinetic energy and surface energy. The simulated results also show that the low Φ_s can cause the drop to rebound easily under the same impact velocity.