In Physics of Fluids, researchers use principal component analysis along with fluid dynamics simulation models to show the crucial importance of proper fit for all types of masks and how face shape influences the most ideal fit. They modeled a moderate cough jet from a mouth of an adult male wearing a cloth mask over the nose and mouth with elastic bands wrapped around the ears and calculated the maximum volume flow rates through the front of mask and peripheral gaps at different material porosity levels.
Scientists have extensively studied how gastric juices in the stomach break down ingested food and other substances. However, less is known about how complex flow patterns and mechanical stresses in the stomach contribute to digestion. Researchers built a prototype of an artificial antrum to present a deeper understanding of how physical forces influence food digestion based on fluid dynamics. In Physics of Fluids, they reveal a classifying effect based on the breakup of liquid drops combined with transport phenomena.
The WHO and the CDC recommend keeping a certain distance between people to prevent the spread of COVID-19. These social distancing recommendations are estimated from a variety of studies, but further research about the precise mechanism of virus transport is still needed. In Physics of Fluids, researchers demonstrate normal breathing indoors without a mask can transport saliva droplets capable of carrying virus particles to a distance of 2.2 meters in a matter of 90 seconds.
COVID-19 can spread from asymptomatic but infected people through small aerosol droplets in their exhaled breath. Most studies of the flow of exhaled air have focused on coughing or sneezing; however, speaking while near one another is also risky. In Physics of Fluids, scientists used smoke and laser light to study the flow of expelled breath near and around two people conversing in various relative postures commonly found in the service industry, such as in hair salons, medical exam rooms, or long-term care facilities.
A restaurant outbreak in China was widely reported as strong evidence of airflow-induced transmission of COVID-19, but it lacked a detailed investigation about exactly how transmission occurred. In Physics of Fluids, researchers at the University of Minnesota report using advanced simulation methods to capture the complex flows that occur when the cold airflow from air conditioners interacts with the hot plume from a dining table and the transport of virus-loading particles within such flows.
Simply wearing a mask may not be enough to prevent the spread of COVID-19 without social distancing. In Physics of Fluids, researchers tested how different types of mask materials impacted the spread of droplets that carry the coronavirus when we cough or sneeze. Every material tested dramatically reduced the number of droplets that were spread. But at distances of less than 6 feet, enough droplets to potentially cause illness still made it through several of the materials.
Even though it has been widely known that wearing a face mask will help mitigate the community spread of COVID-19, less is known regarding the specific effectiveness of masks in reducing the viral load in the respiratory tracts of those wearing them. In Physics of Fluids, researchers examined the effect of wearing a three-layer surgical mask on inspiratory airflows and the mask’s effects on the inhalation and deposition of ambient particles in the upper respiratory airways.
Simulations have been used to predict droplet dispersal patterns in situations where COVID-19 might be spread and results in Physics of Fluids show the importance of the space shape in modeling how droplets move. The simulations are used to determine flow patterns behind a walking individual in spaces of different shape. The results reveal a higher transmission risk for children in some instances, such as behind quickly moving people in a long narrow hallway.
The ongoing COVID-19 pandemic has led many to study airborne droplet transmission in different conditions and environments, and in Physics of Fluids, researchers from A*STAR conducted a numerical study on droplet dispersion using high fidelity air flow simulation. The scientists found a single 100-micrometer cough droplet under wind speed of 2 meters per second can travel up to 6.6 meters and even further under dry air conditions due to droplet evaporation.