A Study of the Motions of Colloidal Particles in a Drying Film Using Lattice Boltzmann Method

Abstract

Self-assembly of colloidal particles in a drying film is one of the most promising methods for organizing microstructures. Due to the complexity of numerical methods for simulating a multiphase flow with moving boundaries, however, numerical simulations of the self-assembly have rarely been performed except for a few lattice Boltzmann (LB) simulations. We combine the pseudo-solid model (PSM) and the diffusion-dominated evaporation model in the present LB simulations to simulate the evaporation of a thin film containing colloidal particles. The PSM can effectively capture the immersed capillary effect, concentration gradient of colloids, and surface deformation caused by particles during evaporation. Two types of forces including hydrodynamic and capillary forces are implemented in the PSM and their relative contributions on particle movements are examined. Specifically, we find that the capillary force can induce unphysical motions of particles due to the diffusive interface of particles. We propose an effective method to alleviate such phenomenon.