| Abstrakt: |
This study investigates outdoor public health by predicting the airflow fields and probabilistic size of breathing zones. Computational fluid dynamics (CFD) simulations were performed in a simplified semi-outdoor domain, utilizing a validated computer-simulated person (CSP) with an integrated nasal cavity. The simulations were conducted for eight wind orientations (0°, 90°, 180°, 270°, 45°, 135°, 225°, and 315°), four wind velocities (U ref = 0.25, 0.5, 0.75, and 1.0 m/s), and one inhalation flow rate (18.7 L/min), considering both steady and transient conditions. The RANS-based equations were solved using the SST k-omega turbulence model. Breathing zones were computed and visualized using the scale for ventilation efficiency 5 (SVE5) and reverse time-traced vector techniques. The results indicated that wind orientation influenced the air velocity, temperature, and breathing zone distribution. The steady-state condition tended to overestimate breathing zones, whereas, under transient conditions, they assumed a semi-cylindrical form that extended horizontally, with a slight slope from the nostrils towards the direction of the wind source. The horizontal extension of the breathing regions increased at high wind speeds and with a smaller cylinder radius compared to calm conditions. Eventually, this study proposed new definitions of the breathing zone in the semi-outdoor environment in different SVE5 values. These findings can contribute to air quality management and aid in assessing the probability of airborne transmission in public spaces. • The airflow field and breathing zones in semi-outdoor environment were predicted using CFD simulations. • A new definition of breathing zones was provided under transient breathing conditions. • The wind orientation influences the size and configuration of breathing zones. • Outdoor wind velocity and breathing conditions affect the probabilistic size of breathing zones. [ABSTRACT FROM AUTHOR] |
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