Numerical study of particle resuspension in the wake of a rotating wheel

Road vehicles are a significant source of dust resuspension, contributing substantially to air pollution. This study presents a novel computational fluid dynamics (CFD) approach to quantify emission factors of resuspended particulate matter (PM) caused by the turbulent airflow around a rotating vehicle wheel. A coupled Eulerian-Lagrangian method incorporating a particle detachment model was employed to simulate the complex interactions between the particles and the airflow surrounding a moving/rotating wheel. Unsteady Reynolds Averaged Navier-Stokes (URANS) simulations were performed using the Shear Stress Transport (SST) and Low-Reynolds-Corrected Turbulence Model (LCTM) for the closure. Comparison to experimental data showed that the LCTM model better captured both global and local flow features.

The particle detachment model was applied to four representative PM₁₀ particle sizes (D₁=0.85 μm, D₁=2.5 μm, D₃=6 μm, and D₄=10 μm), revealing size-dependent resuspension behavior. Finer particles ($D_1,D_2$) detached from regions near the wheel, while larger particles ($D_3,D_4$) were detached over broader areas around the wheel. The emission factor of PM₁₀ particles was calculated as the mass of emitted particles per second. The results showed a good agreement with experimental estimates under similar conditions, thereby confirming the robustness of the present CFD-based methodology. Resuspended particles were subject of dispersion with patterns that showed also distinct behavior across particle sizes: $D_1$ particles closely followed airflow streamlines, $D_2$ particles exhibit enhanced diffusion within and around vortices, and $D_4$ particles tended to accumulate at vortex peripheries, reaching higher vertical positions in the flow field. This original approach will allow to investigate the contribution of resuspended particles to the particulate pollution under several conditions.