Effect of solid-fluid interaction strength on water droplet placed centrally at the curved surfaces using lattice Boltzmann method

In this study, we present a numerical investigation of the effect of solid-fluid interaction strength on the wettability and hydrophobicity of curved surfaces using a two-dimensional (2D) pseudo-potential multiphase lattice Boltzmann method with a D2Q9 model for various solid-fluid interaction strengths of the range varies from -1.30 to -2.90. Initially, simulation of the equilibrium state of a water droplet on a flat surface is considered for various interaction parameters to examine the accuracy of the present numerical model and calculate the contact angle. Contact angles for different values of interaction strength have been validated qualitatively with the previous results. We then imposed the semi-circular concave-shaped surfaces with different radii of curvature. The radii of the droplets are varied from 30 to 60 lu in the domain of 200x200 lattice units. The study shows that increasing the solid-fluid interaction parameter of the curved surfaces dramatically increases the contact area between water droplets and solid walls and hence increases the hydrophobicity. The hydrophobicity is analyzed by measuring the contact angle between the solid and fluid-vapor interface. This study also shows the effect of saturation temperature on the hydrophobicity of the surfaces.