Simulating wetting phenomenon on curved surfaces based on the weighted-orthogonal multiple-relaxation-time pseudopotential lattice Boltzmann model

In this work, our recently developed weighted-orthogonal multiple-relaxation-time pseudopotential lattice Boltzmann (PLB) model [J. Tang et al., “Multiphase flow simulation with three-dimensional weighted-orthogonal multiple-relaxation-time pseudopotential lattice Boltzmann model,” Phys. Fluids 33, 123305 (2021)] is further extended to simulate the complex wetting phenomenon on curved surfaces at large density ratios (ρl/ρg∼1000), where a new geometrical formulation scheme is proposed to characterize the wettability of the curved boundary. Compared with the existing geometrical formulation schemes, the significant advantage of the new scheme is that the characteristic vector representing the phase interface is no longer needed, and, thus, the complex calculations induced by the characteristic vector are avoided, which significantly simplifies computations and facilitates the implementation of the geometrical formulation scheme on curved boundaries. Meanwhile, it is applicable to both two-dimensional and three-dimensional (3D) simulations and maintains the feature of setting the contact angle explicitly. Furthermore, the numerical results of four classical wetting phenomenon benchmark cases at large density ratios predicted by the present model agree well with the analytical solutions, numerical results, or experimental results in the literature. It exhibits the capability of the present model coupled with the proposed scheme to simulate the wetting phenomenon involving curved surfaces with good numerical accuracy. Note that, to the author's knowledge, this is the first time that the geometrical formulation scheme has been successfully adopted in the 3D PLB model to simulate the wetting phenomenon on curved surfaces. We believe that this work lays the foundation for further application of the PLB model to the complex wetting phenomenon.