Droplets containing the COVID-19 virus could enter the respiratory system of humans during breathing. &nbsp;Sneezing, coughing, breathing, and talking of an infected person could generate aerosolized virus-containing droplets. Earlier studies were focused on transmission by sneezing and coughing. Recent studies showed that breathing and talking produce virus-infected droplets that would lead to the spread of COVID-19. In this paper, the emission of droplets/particles while talking was studied. Coronaviruses are of the order 120 nm and are suspended in saliva liquid, which is mostly water. &nbsp;These droplets quickly evaporate when they are expelled in low humidity environments and a collection of viruses with some liquid remaining. As these particles are small, the effect of gravity is negligible, and therefore they can remain suspended in the air for a long time.&nbsp; Also, these small particles in a size range of 100 nm to 1 micron can more easily penetrate the deep respiratory passages causing the transmission of infectious diseases.In this study, two mannequins sitting in a room was considered, and it was assumed that one of the mannequins was emitting virus-infected droplets.&nbsp; The computational fluid dynamics method with ANSYS-Fluent software was used to simulate the airflow and droplet dispersion in the room.The Eulerian approach was used to model the airflow, and the Lagrangian approach was employed to model the discrete phase particle movements. The study investigated the effect of the air ventilation system on the dispersion of droplets/particles and the chance for transmission of the virus to another person sitting in a room. Two air distribution systems, namely, the displacement and mixing ventilation, were considered. Simulation results for a range of droplet sizes and ventilation conditions were presented.&nbsp; These included airflow velocity contours and velocity vector plots at different sections and particle trajectories for different sizes.&nbsp;&nbsp; Simulation results showed that droplets remain suspended in the room for a relatively long time after evaporation. In addition, a large percentage of smaller particles were removed by the ventilation system. &nbsp;The large particles, however, were deposited quickly due to gravitational sedimentation.&nbsp; The particle concentrations in the room for the mixing and displacement ventilation systems were evaluated.

Dispersion of Particles Coming Out of the Mouth While Speaking in a Ventilated Indoor Environment

Paper Proceedings: https://asmedigitalcollection.asme.org/FEDSM/FEDSM2021/volume/85284

ASME 2021 Fluids Engineering Division Summer Meeting (FEDSM2021)

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