| Abstract [eng] |
The assessment of human exhaled aerosol dispersion during respiration, coughing, sneezing, and speaking is complicated by the small size of particulate matter and droplets released with aerosol. The aim of master's thesis was to determine the parameters of dispersion of human exhaled aerosol droplets in a confined space by computational fluid dynamics. The literature review part consists of a review, complex evaluation, and analysis of the scientific literature on human exhaled aerosol, the specifics of human respiration and the application of computational fluid dynamics to aerosol dispersion research. The research methodology part describes the research methodology, experimental model, research plan and work sequence. Research results part consists of the dispersion of human exhaled aerosol droplets evaluation experiments results modeled using the software "Ansys CFX". Studies have shown that human exhaled aerosol droplets bounce ~ 4 times faster to opposite surfaces at a distance of 1.5 m from the source of dispersion than to more distant surfaces. At this distance, human-exhaled aerosol droplets have the highest kinetic energy to adhere to other surfaces. Aerosol droplets released during coughing / sneezing reach the maximum distance in a straight trajectory, and aerosol droplets released during speech remains in the straight trajectory the longest time. Aerosol droplets (size 3.5 µm) released during coughing / sneezing reach a maximum distance of 4.0 m in a straight trajectory within 15.3 sec, when the droplets (size 5.5 µm) during speech reach a maximum distance of 3.9 m in 29.0 sec. During nasal respiration, aerosol droplets (size 0.8 µm) reach a maximum distance of 2.95 m in a straight trajectory within 22.0 sec, while during oral respiration aerosol droplets (size 0.8 µm) reach a maximum distance of 2.65 m within 21.8 sec. During human speech, the exhaled aerosol has been shown to be effectively stopped by a protective face shield that changes the aerosol flow trajectory and reduces aerosol droplets velocity. Face shields can only be used during short-term contact with other people, as they do not perform the function of aerosol containment and filtration, so aerosol droplets spread in all directions around the shield. |
