Numerical investigation of wake flow effects on particulate matter dispersion characteristics based on the DrivAer Estateback model

In urban environments, particulate matter emitted and entrained by vehicles during travel constitutes a significant component of air pollutants. This study investigates particulate matter dispersion in vehicle wake flows at speeds of 10–25 m/s using the DrivAer Estateback model, Shear Stress Transport k-ω Improved Delayed Detached Eddy Simulation turbulence models, and Lagrangian particle tracking. Combining full-scale numerical simulations with gas-solid coupling analysis and proper orthogonal decomposition (POD), it reveals the correlation between turbulent structures and particle motion. Results show the vehicle rear wake features strong turbulence and a negative pressure zone. At low speeds (10,15 m/s), broader but lower-energy turbulence increases particle vertical/lateral dispersion, with residence time up to 3.0 s, elevating pedestrian exposure risk. At high speeds (20,25 m/s), eddies propagate farther, main airflow drives particles downstream rapidly, reducing mass flow decay while increasing far-field particle velocity to 30 m/s, worsening visibility for following vehicles. POD analysis indicates the first-order modal energy proportion decreases with speed, with the top 10 modes' total energy dropping from 87.9% to 68%, as enhanced high-order small-scale disturbances complicate particle trajectories. Findings provide a theoretical basis for aerodynamic design to mitigate road dust pollution.