Wetting dynamics and particle deposition for an evaporating colloidal drop: a lattice Boltzmann study.

A three-dimensional lattice Boltzmann method (LBM) has been developed for multiphase (liquid and vapor) flows with solid particles suspended within the liquid phases. The method generalizes our recent two-dimensional model [A. Joshi and Y. Sun, Phys. Rev. E 79, 066703 (2009)] to three dimensions, extends the implicit scheme presented therein to include interparticle forces and introduces an evaporation model to simulate drying of the colloidal drop. The LBM is used to examine the dynamical wetting behavior of drops containing suspended solid particles on homogeneous and patterned substrates. The influence of the particle volume fraction and particle size on the drop spreading dynamics is studied as is the final deposition of suspended particles on the substrate after the carrier liquid evaporates. The final particle deposition can be controlled by substrate patterning, adjusting the substrate surface energies and by the rate of evaporation. Some of the envisioned applications of the model are to develop a fundamental understanding of colloidal drop dynamics, predict particle deposition during inkjet printing of functional materials and to simulate the drying of liquids in porous media.