Improved implementation of wettability in the phase-field lattice Boltzmann method for simulating droplet impacts on cylindrical targets

An improved wettability implementation in the phase-field lattice Boltzmann method for simulating the impact of a droplet onto a cylindrical target is developed. Contact angle control is achieved through a cubic wetting boundary condition that allows precise modeling of wettability. To handle curved surfaces, quadratic interpolation and an image point technique are used to enforce accurate boundary conditions and contact angles. A filtering process is also applied to the phase-field variable to reduce nonphysical artifacts near the interface, ensuring stability and accuracy. The method's validity is demonstrated by simulating droplet impacts on cylindrical surfaces with varying contact angles, from 10° to 170°. Our numerical method provides accurate predictions of the droplet's post-impact phenomena, such as lamella formation, droplet splitting, and film thickness evolution. The numerical results are validated against experimental data and theoretical models, demonstrating good agreement in both qualitative and quantitative aspects.