Molecular dynamics simulations of wetting behaviors of droplets on surfaces with different rough structures

Chen, Yanling; Guo, Liang; Sun, Wanchen; Cai, Ningning; Yan, Yuying

Abstract

Aiming at the wall-wetting problem in internal combustion engines, to actively control the behaviors of fuel droplets after hitting the walls, the molecular dynamics method is used to investigate the effects of the surface wettability and rough structure on the static and dynamic wetting behaviors of the droplets. The results show that the droplet diameter has little influence on the intrinsic contact angle. With the decrease of the solid-liquid interaction coefficient, the interaction between the wall and the droplet is weakened, and the wetting state changes from the Wenzel state to the Cassie state, resulting in an increase in the static contact angle. As the ratio of the solid-liquid contact area to the composite contact area decreases, it is easier for the droplet to reach the Cassie state. Compared with the smooth surfaces, the structures of the rough surfaces have an inhibitory effect on the spreading of the droplets. The apparent contact angles of the droplets on the rough surfaces with different structures are larger than their intrinsic contact angles on the smooth surfaces. The secondary boss-shaped structures can significantly enhance the surface oleophobicity. In addition, with the decrease of the solid-liquid interaction coefficient, the contact angle hysteresis reduces. Compared with the Wenzel state, the droplet in the Cassie state has a smaller contact area with the surface, which makes the interaction between the wall and the droplet weaker, leading to a decrease in the contact angle hysteresis.

• Journal Article Type: Article
• Acceptance Date: Sep 12, 2023
• Online Publication Date: Sep 14, 2023
• Publication Date: 2023-12
• Deposit Date: Oct 30, 2023
• Publicly Available Date: Sep 15, 2024
• Journal: International Journal of Multiphase Flow
• Print ISSN: 0301-9322
• Publisher: Elsevier
• Peer Reviewed: Peer Reviewed
• Volume: 169
• Article Number: 104613
• DOI: https://doi.org/10.1016/j.ijmultiphaseflow.2023.104613
• Keywords: Droplet; Wettability; Rough structure; Contact angle; Molecular dynamics
• Public URL: https://nottingham-repository.worktribe.com/output/26795122
• Publisher URL: https://www.sciencedirect.com/science/article/pii/S0301932223002331