Liquid drops on homogeneous and chemically heterogeneous surfaces: A two-dimensional lattice Boltzmann study

A boundary condition of a two-phase lattice Boltzmann (LB) method is proposed to model smooth substrates of chemically heterogeneous surfaces. The present technique is applied to the LB simulations of liquid drops on homogeneous, regularly heterogeneous, and randomly heterogeneous surfaces. It is found (i) that the LB technique can mimic not only homogeneous substrates with arbitrary wettabilities but also chemically heterogeneous substrates with arbitrary heterogeneities and wettabilities and (ii) that, in the presence of surface heterogeneities, it also can capture the contact line pinning, the contact angle hysteresis, and the effects of size and distribution of the heterogeneities on them. The results indicate that the present LB method is useful for the simulation of wetting phenomena of chemically heterogeneous surfaces.