The impact of human-induced turbulence on indoor thermal environment and pollutant diffusion

Turbulence induced by human movement is thought to affect the dispersion of pollutants in indoor environments. In this study, eight classical crowd scenarios were numerically simulated to investigate the effects of human movement on indoor air pollution in different scenarios. High-level simulations were performed into human movement, respiration, and heat dissipation, and differential analyses of the simulation results for different flow scenarios were conducted to investigate the interactions between individuals. Research has shown that people walking create significant wake currents within approximately 1.1 m on either side of their path and within 3–4 m behind them. When two pedestrians crossed paths, the wind speed increased significantly to 1.87 m/s compared with a single person walking at 1 m/s. The greatest mutual interference in pollutant distribution occurs when two individual cross paths are perpendicular, with a critical interference distance threshold of 2.87 m. Carbon dioxide concentrations fluctuate, surpassing 1,000 ppm within ten minutes at a density of 1.52 persons per square meter. Additionally, the dispersion of aerosol particles is significantly influenced by the relative direction of movement between individuals and pollutant sources. Calculated “safe distance” to avoid inhalation of exhaled aerosols in short flow exposure scenarios is at least 3.4 m. The personnel wake disturbance intensity was defined based on the rate of change in the velocity amplitude in the personnel wake region, the wake deformation rate, and the dissipation time. These insights can guide improvements in indoor air quality and health risk reduction in densely populated spaces.