Study on the impact of transient turbulence induced by head movements on the dynamic exposure to infectious respiratory particles

Non-verbal head movements in social interactions are recognized as a key dynamic factor influencing the entire process from the release to the exposure of infectious respiratory particles (IRPs). The effects of transient turbulence induced by head movements on IRP exposure are analyzed, and potential high-exposure risks are identified, which is crucial for understanding the impact of head movements on IRP exposure. In this study, a three-person discussion scenario in a meeting room is utilized as a case study, with large eddy simulation (LES) and sliding mesh techniques employed to investigate the impact of head movements on IRP release, diffusion, and inhalation exposure. The high-exposure risks associated with head movements are quantified, and the results obtained using LES and Reynolds-averaged Navier-Stokes (RANS) methods are compared. It is shown that variations in the exposure values for each breathing interval of the target manikin are led by the head-shaking movements of the source manikin, with significant instantaneous high-exposure intervals observed. Specifically, the right-side target manikin experiences an instantaneous exposure peak 2.9 times higher than that under the static condition. Little effect on the distribution of exposure data is shown to be had by the direction of head rotation in the target manikin. However, significant differences in peak exposure are observed, with a maximum difference of 46% noted compared to the static case. During close-range interactions, substantial variations in instantaneous exposure levels occur due to dynamic head movements, underscoring the importance of studying head movements in real-life interactive scenarios. This study elucidates the coupling mechanism of “head movement – transient turbulence – dynamic exposure,” providing important insights into understanding the transmission dynamics of respiratory diseases, improving indoor ventilation designs, and developing individual preventive strategies.