The Effects of Patient Movement on Particles Dispersed by Coughing in an Indoor Environment

Abstract

This study investigates the influence of a moving patient on the transport characteristics of coughing particles by dynamic meshing and the Lagrangian particle tracking method. Through simulation, particle movement during the initial coughing, patient movement, and stationary flow phases was examined. Two different particle sizes (5 μm and 10 μm) were used and yielded small differences in the initial airflow after coughing. During the patient-moving phase, the temporal particle distribution in the upper, breathing, lower, and near-floor zones were simulated. The amplified air-velocity field induced by the moving patient enhanced the particle entrainment, thus increasing the risk of contamination (defined as particle system entropy) in the whole room. Both temporal and final particle distribution during the stationary flow phase were studied. Walking speed affected the particle distribution in the traveling direction, but not in the vertical or lateral directions at the end of the simulation. Turbulence dispersion played a critical role in the spread of the particles through the coughing and patient-moving phases.