As COVID-19 spreads via respiratory droplets, researchers have become increasingly interested in the drying of droplets on impermeable and porous surfaces; surfaces that accelerate evaporation can decelerate the spread of the virus. In Physics of Fluids, researchers show a droplet remains liquid for a much shorter time on a porous surface, making it less favorable to survival of the virus. On paper and cloth, the virus survived for only three hours and two days, respectively.
To find out how the COVID-19 virus survives on surfaces, researchers in India are exploring the drying times of thin liquid films that persist on surfaces after most respiratory droplets evaporate. While the drying time of typical respiratory droplets is on the order of seconds, the survival time of the COVID-19 virus was found to be on the order of hours. In Physics of Fluids, the researchers describe how a nanometers-thick liquid film clings to the surface, allowing the virus to survive.
As the pandemic continues, researchers have increasingly focused on the extent to which respiratory droplets carrying the coronavirus travel and contaminate the air after an infected person coughs. While scientists have studied the properties of air at the mouth, less is known about how these properties change as the cough cloud travels. In Physics of Fluids, researchers estimate the evolving volume of the cough cloud and quantify the reduction in its volume in the presence of a face mask.
Since the COVID-19 virus spreads through respiratory droplets, researchers in India set out to explore how droplets deposited on face masks or frequently touched surfaces dry. Droplets can be expelled via the mouth or nose and studies have shown a substantially reduced chance of infection once they dry. In Physics of Fluids, the researchers publish their findings that surface wetting properties to reduce the drying time of droplets could help lessen the risk of infection from coronaviruses.