ABSTRACT
This multidisciplinary study provides a comprehensive visualization of airborne aerosols and droplets coming into contact with crossflows of moving air utilizing both experimental particle measuring methods and multiphase computational fluids dynamics (CFD). The aim of this research is to provide a Eulerian visualization of how these crossflows alter the position and density of an aerosol cloud, with the goal of applying this information to our understanding of social distancing ranges within outdoor settings and ventilated rooms. The results indicate that even minor perpendicular crossflows across the trajectory of an aerosol cloud can greatly reduce both the linear displacement and density of the cloud, with negligible increases in density along the flow path. © 2022 American Society of Mechanical Engineers (ASME). All rights reserved.
ABSTRACT
This research will study a novel aspect of the physics of COVID-19 transmission associated with actively altering droplet size distribution. Viruses can be transmitted through droplets and aerosols released during speaking, sneezing, and coughing phenomena. We previously found that these distributions can be altered using food ingredients. The study will be carried out to study the hypothesis of relaxed guidance in social distancing and mask usage is possible with the proposed approach using CFD models of human sneezes. The adult human is positioned inside a ventilated room condition and the droplet/aerosols are to be released to explore the impacts of the various distributions that relate to how the food ingredients vary the function, hence, the size of the droplets will be the function of the use of food ingredients. Results study the concentration of droplet particles at various distances away from the mouth, also called exposure maps and indicate that Corn Starch and Xanthum usage increase the exposure intensity level, while Xanthum reducing the exposure area implies that social distancing can be reduced with its use. In contrast, the use of Lozenge and Zingiber reduces the exposure level, related to the increase in the viscosity and reduction of the mass flow rate of saliva. Copyright © 2022 by ASME.
ABSTRACT
One key factor in stopping the spread of COVID-19 is practicing social distancing. Visualizing possible sneeze droplets' transmission routes in front of an infected person might be an effective way to help people understand the importance of social distancing. This paper presents a mobile virtual reality (VR) interface that helps people visualize droplet dispersion from the target person's view. We implemented a VR application to visualize and interact with the sneeze simulation data immersively. Our application provides an easy way to communicate the correlation between social distance and infected droplets exposure, which is difficult to achieve in the real world.
ABSTRACT
Recent studies have indicated that COVID-19 is an airborne disease, which has driven conservative social distancing and widescale usage of face coverings. Airborne virus transmission occurs through droplets formed during respiratory events (breathing, speaking, coughing, and sneezing) associated with the airflow through a network of nasal and buccal passages. The airflow interacts with saliva/mucus films where droplets are formed and dispersed, creating a route to transmit SARS-CoV-2. Here, we present a series of numerical simulations to investigate droplet dispersion from a sneeze while varying a series of human physiological factors that can be associated with illness, anatomy, stress condition, and sex of an individual. The model measures the transmission risk utilizing an approximated upper respiratory tract geometry for the following variations: (1) the effect of saliva properties and (2) the effect of geometric features within the buccal/nasal passages. These effects relate to natural human physiological responses to illness, stress, and sex of the host as well as features relating to poor dental health. The results find that the resulting exposure levels are highly dependent on the fluid dynamics that can vary depending on several human factors. For example, a sneeze without flow in the nasal passage (consistent with congestion) yields a 300% rise in the droplet content at 1.83 m (≈6 ft) and an increase over 60% on the spray distance 5 s after the sneeze. Alternatively, when the viscosity of the saliva is increased (consistent with the human response to illness), the number of droplets is both fewer and larger, which leads to an estimated 47% reduction in the transmission risk. These findings yield novel insight into variability in the exposure distance and indicate how physiological factors affect transmissibility rates. Such factors may partly relate to how the immune system of a human has evolved to prevent transmission or be an underlying factor driving superspreading events in the COVID-19 pandemic.