  Droplet impact behavior has attracted much attention recently due to its
academic significance and diverse industrial applications. This study employs
the lattice Boltzmann method to simulate the impact of a droplet on a
hydrophobic plate featuring a square orifice. Unlike previous studies, the
chemical property of the orifice considered in this work is not homogeneous but
heterogeneous, and its cross-sectional wettability changes from hydrophobicity
to hydrophilicity. The study first validates the numerical method against
experimental data, and then investigates in detail the influences of the Weber
number, wettability difference, and pore size. According to the numerical
results, we observed that the evolutionary stages of the impinging droplet
always include the spreading phase and the rebounding phase, while whether
there exists the splitting phase, it depends on the combined effect of the
wettability difference and the Weber number. The impact behavior of droplets is
analyzed by evaluating the underlying mechanisms such as kinetic energy,
surface energy, viscous dissipation energy, and pressure. It is interesting to
note that the existence of wettability-patterned pore tends to promote adhesion
of droplets on the plate, resulting in the droplet impact behaviors are largely
different from that for the case of homogeneous pore. Additionally, a phase
diagram is constructed for various Weber numbers and pore sizes, revealing that
the dynamic behavior of droplets is determined by the competition among dynamic
pressure, capillary pressure, and viscous pressure losses. These insights from
numerical studies guide the development of innovative solid substrates capable
of manipulating droplet motion.
