Lattice Boltzmann Simulation of Bidirectional Anisotropic Droplet Sliding on Bioinspired Superhydrophobic Inclined Channels

Abstract

This study employs the lattice Boltzmann method (LBM) to systematically investigate the sliding behavior of droplets on inclined superhydrophobic surfaces with macroscopic ridged structures, delving into the surface hydrophobicity and anisotropic sliding phenomena. Mimicking the microstructures of rice leaves and butterfly wings, a model of a macroscopically ridged superhydrophobic surface with periodic arrangements is constructed. Numerical simulation results indicate that the macroscopic ridge structure exerts directional pinning effects by manipulating the three-phase contact line (TPCL). Under critical groove configurations (the inclination angle of the groove γ_a = 65-85°, groove width L = 22-25 l.u.), high contact angles of 150° ± 2° are achieved through capillary suppression and TPCL stabilization. The bidirectional sliding anisotropy results from competing resistance mechanisms. In the forward direction along the groove inclination, the sliding angles are smaller due to the reduced curvature of the TPCL. Conversely, in the reverse direction opposite to the groove inclination, the adhesion forces are enhanced via the normal reaction components. When γ_a > 60°, the geometric symmetry mitigates the pinning heterogeneity, reducing the bidirectional disparity to < 6°. These findings validate a comprehensive modeling framework that synergistically combines contact line dynamics and geometric parameter optimization. This framework is specifically designed for the development of bioinspired microfluidic channels, where programmable directional liquid transport is precisely regulated by groove inclination angles.