Impacts of Modelling Simplifications on Predicted Dispersion of Human Expiratory Droplets

摘要

Person-to-person transmission of droplets and droplet nuclei during expiratory activities constitutes a prerequisite for airborne and droplet-borne infections. This study focuses on the impact of modelling simplifications on one manikin's exposure to the other's expiratory droplets via breathing. The exhalation airflows are compared and validated by measurement results of human subjects. The flow field between two manikins are found significantly influenced by their exhalation airflows. Mono-dispersed droplets with an initial diameter of 10 μm are released from one breathe of a manikin. All droplets are found to become droplet nuclei before reaching the other manikin. Though the flow field is not quite influenced by the room macroenvironment, the room air conditions affect the dispersion of droplet nuclei significantly. Direct exposure of expiratory droplet nuclei are found to be overestimated, when simplifying the room air condition into isothermal condition, or neglecting the body plume of the manikin. It will also change the microenvironment completely by simplifying the shape of human grid in to a robot shape. The trajectories of both the exhalation airflows and droplet nuclei are significantly different from a detailed shape of human body and mouth.