Numerical Investigation of Particle Dispersion and Deposition in a Ventilated Room: A Lagrangian Force-Resolved Approach

Understanding the transport and fate of micron-scale particles in ventilated indoor environments is vital for applications in public health, air filtration, and microclimate design. This study presents a validated numerical investigation of particle-laden turbulent airflow in a model room, replicating a benchmark experiment with silver-coated hollow glass spheres. Using URANS and LES flow solvers, key forces such as gravity, drag, and pressure were resolved within a three-dimensional Lagrangian tracking framework. Particles were injected at a constant rate into a steady flow field. URANS predicted limited dispersion due to unresolved turbulence, while LES captured gravitational settling, wall rebound, and spatial concentration gradients, especially near recirculation zones. Particle behavior was strongly size-dependent: larger particles settled and deposited near surfaces, while smaller ones dispersed more uniformly. Simulated concentration profiles matched Phase Doppler Anemometry data, validating the approach. The study underscores the need for turbulence-resolving, force-based models for accurate particle transport predictions in indoor airflow applications.