posted on 2023-11-02, 10:40authored byLing-Zhe Zhang, Xu Chen, Yi-Feng Wang, Yan-Ru Yang, Shao-Fei Zheng, Duu-Jong Lee, Xiao-Dong Wang
Extensive
research has shown that a superhydrophobic cylindrical
substrate could lead to a noncircumferential symmetry of an impacting
droplet, reducing the contact time accordingly. It is of practical
significance in applications, such as anti-icing, anticorrosion, and
antifogging. However, few accounts have adequately addressed the off-centered
impact of the droplet, despite it being more common in practice. This
work investigates the dynamic behavior of a droplet off-centered impacting
a superhydrophobic cylinder via the lattice Boltzmann method. The
effect of the off-centered distance is primarily discussed for droplets
taking various Weber numbers and cylinder sizes. The results show
that the imposition of an off-center distance can further disrupt
the droplet symmetry during the impact. As the off-center distance
increases, the droplet movement is gradually tilted toward the offset
side until it tangentially passes the cylinder side, resulting in
a direct dripping mode. The dynamic features, focusing mainly on maximum
spreading in the axial direction and contact time, are specifically
explored. A quantitative model of the maximum spreading factor is
proposed based on the equivalent transformation from the off-center
impact into oblique hitting, considering the full range of off-centered
distance. A preliminary contact time model is established for droplet
off-centered impacting superhydrophobic cylinders by substituting
the maximum spreading and the effective velocity of the liquid moving.
This work aims to make an original contribution to the fundamental
knowledge of droplet impact and could be of value for related applications.