关键词: 水滴, 撞击, 表面, 显微结构, 不稳定性

Abstract: The dynamic behavior of droplets impacting on micropillared and micropored surfaces was investigated in this paper. The results showed that when the droplet impacted on the micropillared surface,the droplet appeared the spreading and retraction processes. With the increase of Weber number(We),the spreading diameter increased. Meanwhile,the satellite droplets appeared. However,the time to reach the maximum spreading diameter was the same. When the droplet with the same velocity(the same We) impacted on micropillared surfaces with different pitch between micro pillars,the maximum spreading diameter decreased with the increase of the pitch,and the wetting state was instability. The wetting state transited from the Cassie state to the Wenzel state during the spreading process. When the pitch was small,The smaller the adhesion work is,the more likely to occur to the Cassie state. Moreover,the dynamic behaviors of a droplet impacting on micropored hydrophobic surfaces were compared with the micropillared surfaces. The droplet was spreading and retracting on micropored surfaces. In the impacting process,the wetting state did not transit into the Wenzel state. The phenomenon was analyzed by using the established physical model.

Key words: droplets, impact, surface, microstructure, instability