Transport mechanisms of airborne particulate matters in partitioned indoor environment

The main objective of this study is to investigate the transport mechanisms of size-dependent airborne particulate matters in partitioned indoor environment. A three-dimensional Lagrangian particle tracking model is developed herein and validated by reliable experimental measurement. Four major particle-driving mechanisms (the gravitational force, the drag force, the Brownian motion force and the Saffman lift force) are considered in the model. Five kinds of particle transport mechanism scenarios are performed, including the dynamic equation scenario (all considered), the Brownian-motion-neglected scenario, the drag-force-neglected scenario, the lift-force-neglected scenario, and the inertial-force-neglected scenario (neglecting both the drag force and lift force). Seven different particle aerodynamic diameters (10, 5, 2.5, 1, 0.5, 0.1 and 0.05 μm), ranging from coarse to ultra-fine particle ranges, are used to investigate the relationship between particle size and each transport mechanism scenario. The results show that the influence of the drag force and the inertial force is significant for particle diameter larger than 1 μm, and the Brownian motion force is important for particle diameter smaller than 0.5 μm. The Saffman lift force cannot be neglected in a specific range of particle sizes between 2.5 and 5 μm.