Numerical Analysis of Spreading of Liquid Droplet on a Heterogeneous Surface by the Lattice Boltzmann Method

In this paper, the behavior of a micron-scale fluid droplet on a heterogeneous surface is investigated using a two-phase lattice Boltzmann method. The solid surface is uniform hydrophilic substrate separated by a hydrophobic strip on the central line. The dependence of spreading behavior on wettability, the width of hydrophobic strip and gravity is investigated. A decrease in contact angle of the liquid on a hydrophilic surface leads to break up of the droplet for certain substrate patterns. The two-phase Lattice Boltzmann Method (LBM) permits the simulation of the time dependent threedimensional motion of a liquid droplet on solid surface patterned with hydrophobic and hydrophilic strips. A nearest-neighbor molecular interaction force is used to model the adhesive forces between the fluid and solid surface. The model is validated by demonstrating consistency of the measured dynamic contact line with experimentally measured surface properties and observed surface shapes. The simulations suggest that the present lattice Boltzmann model can be used as a reliable way to study fluidic control on heterogeneous surfaces and other wetting related subjects.