Numerical investigation of the transport of high-temperature submicron and ultrafine particles transiently generated during welding processes

High-temperature aerosols generated during industrial processes pose a significant threat to the operating environment and workers’ health. In this study, the dynamic behaviour of transiently generated aerosols during welding was simulated using the validated Euler–Lagrange approach. The maximum radial diffusion radius ( R ), horizontal dispersity ( D H ) and concentration decay rate loss coefficient ( ζ ) were calculated to quantify the spatiotemporal evolution of different particle size categories. Furthermore, the effect of Brownian forces on aerosols’ dispersion and distribution was systematically investigated. The results showed that welding aerosols larger than 0.2 μm exhibited favourable airflow following and their dispersion patterns tend to be consistent. Conversely, the migration paths of welding aerosols smaller than 0.2 μm deviated significantly from the airflow due to the molecular slip effect. For the 0.05 μm welding aerosol, the strong molecular slip effect resulted in its inability to effectively follow the hot air, showing a disordered dispersion pattern centred on the release source. In addition, Brownian force has a significant enhancement effect on the diffusion capability of 0.1 μm particles, leading to an augmentation in the R from 2 to 2.5 m, and an escalation in the D H from 42.4% to 70%.