Investigating Fine Dust Dynamics: FDS Modelling Aspects

This study evaluates the ability of Fire Dynamics Simulator (FDS) to represent fine‐particle dynamics relevant to industrial and environmental applications. Simulations with 4 μ m silica particles were used to examine how particle number, grid resolution, travel distance, initial time step, and particle grouping affect predicted settling behavior in quiescent and flow‐driven environments. Under quiescent air conditions, coarser meshes showed weak sensitivity to particle number, whereas finer meshes showed a systematic increase in apparent settling velocity with increasing particle loading. A central finding is that slip‐based settling estimates are substantially less sensitive to particle loading than apparent cloud‐settling velocities, indicating that deviations from the analytical Stokes reference increasingly reflect cloud‐induced gas motion rather than particle slip alone. Changes associated with the initial time step remained minor within the tested range. Increasing travel distance reduced the influence of initial transients and improved agreement with the analytical baseline, while the imposed horizontal‐flow case yielded a Stokes number of 4.5 × 10 −7 , indicating minimal inertial lag. Particle grouping preserved the global settling metric while substantially reducing computational cost on the finest tested grid. Overall, the results show that FDS can provide physically useful and computationally efficient predictions of fine dust transport when numerical settings are interpreted with respect to coupling effects and metric definition.