Lattice Boltzmann Modeling of Droplet Impact on a Superhydrophobic Ridge

Abstract

ABSTRACT The impact dynamics of droplets on a single rectangular superhydrophobic ridge are systematically investigated using the lattice Boltzmann method. The effects of ridge width, droplet deviation, and Weber number on droplet deformation and breakup are examined through extensive numerical simulations. The results show that kinetic and surface energies undergo continuous interconversion, while the vertical momentum exhibits a characteristic three‐stage evolution and vorticity is primarily concentrated near the gas‐liquid interface and ridge corners. Depending on the impact conditions, droplets exhibit symmetric or asymmetric deformation and undergo either non‐breakup or breakup into two or three secondary droplets. The breakup behavior is governed by the competition between inertial effect and surface tension, together with the resulting stress concentration near the ridge corners. In general, lower Weber numbers and larger ridge widths favor non‐breakup, whereas higher Weber numbers and larger droplet deviations promote breakup, with deviation favoring breakup into two secondary droplets. Phase diagrams further reveal narrow transition regions between different impact outcomes, enabling the corresponding critical boundaries to be quantitatively described by linear relationships. These findings provide a mechanistic framework for understanding and predicting droplet breakup on structured surface.