Single collector capture model analysis of particle deposition: Effects of hydrodynamics, particle size, and collector geometry

Particle deposition in porous media is critical in natural and engineered systems and has significant implications for groundwater recharge, colloid filtration, and contaminant transport. Therefore, a comprehensive understanding of pore-scale dynamics is essential. Current research mainly focuses on deposition outcomes, whereas dynamic deposition processes require further research, particularly into the coupled effects of flow velocity, particle size, and collector geometry. This study establishes a single-collector model under favorable conditions, using Lagrangian simulations to analyze pore-scale force interactions and particle trajectories. This approach facilitates a systematic investigation of how flow velocity, particle size, and collector geometry influence deposition time, transport trajectory length, and spatial distribution of deposition particles, as well as force analysis of particles. The results showed that particle size and flow velocity primarily control η while collector geometry considerably affects deposition kinetics and spatial patterns. A distinct size-dependent transition in deposition mechanisms was observed, with sub-micron particles (≤1 μm) exhibiting stochastic, diffusion-dominated behavior with dispersed deposition times and trajectories and larger particles (≥2 μm) undergoing rapid, deterministic deposition driven by gravity. Irregular collector shapes enhanced the dispersion and delay of small particle deposition due to complex flow fields with vortices and tortuous streamlines, causing localized deposition hotspots in surface concavities. Force balance analysis shows that in the concave regions of irregular collectors, strong competition occurred Brownian motion and drag force, resulting in more random and tortuous deposition paths. As particle size increased, deposition behavior became shifts to gravity-dominated, with irregular flow fields exhibiting less influence. This study reveals the key role of local flow features in shaping particle deposition behavior, thus providing a deeper understanding of the particle deposition process.