Predicting the interaction between nanoparticles in shear flow using lattice Boltzmann method and Derjaguin–Landau–Verwey–Overbeek (DLVO) theory

Abstract

The functionality and performance of colloidal suspensions used in catalyst layer preparation and biomedical applications are largely dependent on the interaction between nanoparticles in colloidal suspension systems. Previous models (e.g., collision model) usually rely on an artificial repulsive force as the sole interaction between nanoparticles to prevent overlapping, but fail to capture the agglomeration or reveal the effect of solvents. In this study, the Derjaguin–Landau–Verwey–Overbeek (DLVO) theory is implemented in conjunction with a lattice Boltzmann-smoothed profile method developed to simulate the dynamic solid–fluid and particle–particle interactions between nanoparticles in shear flow. Both aqueous and non-aqueous solvents are considered. The model consists of an attractive van der Waals force and repulsive electrostatic and Born forces in aqueous solvents and is modified for non-aqueous solvents by replacing the repulsive electrostatic force by Coulombic repulsion. The numerical model is validated against a benchmark analytic solution for the motion of one nanoparticle in shear flow. For two-particle systems, physically representative simulations are obtained with the DLVO models, resulting in nanoparticles that remain attached or eventually detach depending on a critical particle Reynolds number. Furthermore, the DLVO models properly resolve the effect of solvents on nanoparticle motion. The improved representation of inter-particle interactions achieved with the DLVO and modified-DLVO models provides a physically consistent approach to simulate and investigate agglomeration and dispersion in colloidal suspensions.