An improved fluid–solid interaction force scheme in multirange pseudopotential lattice Boltzmann model for simulating wetting phenomena

An improved fluid–solid interaction force scheme in the multirange pseudopotential lattice Boltzmann model is proposed for simulating wetting phenomena. Different from the existing virtual-density-based fluid–solid interaction force schemes (including the constant virtual-density scheme and piecewise function scheme), which simulate various contact angles by adjusting the virtual density of all solid points in the same way, the present improved scheme simulates various contact angles by only adjusting the virtual density of solid points near the three-phase contact line while keeping the virtual density of solid points near the bulk fluid close to the bulk fluid density. In this way, the present improved scheme can eliminate the gaps between the solid virtual density and the bulk fluid density and thereby eliminate unphysical mass-transfer layers near solid walls, which are often produced by the existing fluid–solid interaction force schemes. The present improved scheme is first validated by simulating the static droplet on a solid wall, and the results demonstrate that it can simulate a wide range of contact angles, eliminate unphysical mass-transfer layers, and suppress spurious currents near solid walls. Then, the present improved scheme is used to simulate the Couette flow, which shows that it can achieve higher numerical accuracy compared to the existing fluid–solid interaction force schemes due to eliminating unphysical mass-transfer layers. Finally, the present improved scheme is adopted to simulate the droplet spreading on a solid wall and capillary intrusion, and the results show that it can accurately simulate dynamic wetting phenomena.