Numerical study on the nonwetting ability of trapezoid topography

Abstract

Pattern texturing has been proved to effectively improve the water repellency on hydrophobic surfaces. To explore the effect of pattern profile on the dynamic wetting state, here, we conduct numerical study of a water droplet impinging on surfaces with a single trapezoid, rectangular, and V-shaped grooves, respectively. Simulations are performed using a volume-of-fluid method based interFoam solver shipped with OpenFOAM. We begin with a numerical validation by comparing with experiment. Subsequently, the wetting states of the droplet on these three substrates are examined, which demonstrate the capability of trapezoid topography to prevent being wetted. Theoretical model well explains that trapezoid structure can lead to a great increase in energy barrier brought by the penetration of liquid–air interface, which in turn improves its non-wetting ability even under impingement conditions. By masking the surface with mix-hydrophobicity, we also prove that wettability in grooves plays a significant role on the dynamic wetting state. A stable dry surface can be obtained by only masking the groove side-wall by superhydrophobic patterns.