The role of particle collisions in enhancing resuspension

The resuspension of fine particles from surfaces exposed to airflow is a phenomenon of great relevance in various scientific and engineering contexts. While traditional models often focus on single-particle detachment driven by aerodynamic forces overcoming adhesion, recent studies have highlighted the significant role of particle–particle interactions, especially in systems with moderate to high surface concentrations. In this work, we develop a Monte Carlo numerical model to investigate the role of collisions as an additional mechanism for particle detachment. The model introduces a probabilistic rule for inter-particle collisions based on particle surface concentration and collision force effect. A parametric study is performed to evaluate how particle surface concentration, particle size, flow velocity, collision efficiency ($\epsilon$) and the number of multiple particle impacts influence the resuspension rates. The results show that at low concentrations, collisions are negligible, and resuspension is governed by direct aerodynamic detachment. However, as the surface becomes more populated, collisions increasingly contribute to particle removal, especially when the velocity and size of moving particles allow sufficient momentum transfer. The efficiency parameter $\epsilon$ controls the fraction of successful detachments upon impact, and even modest values lead to noticeable increases in collisional contributions to resuspension rates. The model also captures the non-linear behavior of resuspension curves and reproduces key experimental trends reported in the literature. Comparisons with experimental data from other authors show that incorporating collisions significantly improves the prediction of resuspension rates at higher deposition densities. In particular, the introduction of multiple particle impacts is crucial to match the sharp increase in detachment observed experimentally. These findings underscore the importance of including particle–particle interactions in theoretical models and suggest that even in relatively dilute regimes, collisions can enhance detachment under appropriate flow conditions.