Dispersion of Evaporating Cough Droplets in Tropical Outdoor Environment

A team of researchers from A*STAR’s Institute of High Performance Computing (IHPC) have published research about the spread of cough droplets in tropical environments, in the scientific journal Physics of Fluids. As part of the study, the researchers have developed a simulation which more accurately models the spread of droplets when a person with COVID-19 coughs in Singapore's tropical environment. The accuracy of the simulation was further verified by A*STAR's Institute of Materials Research and Engineering (IMRE), which used an aerosol generator to recreate the simulated scenarios in real life. Among their many findings, the researchers discovered that a 100 micrometre (µm) cough droplet can travel up to 6.6m at a wind speed of 2m per second (m /s), if the person who coughs is not wearing a mask.

IHPC’s Executive Director, Dr Lim Keng Hui said that while other studies had been done on the spread of cough droplets, they did not take into account factors important to Singapore, starting with the climate here. He added that the research has shown scientific proof that it is very important to wear a mask, practise good personal hygiene, social distancing and ensure well-ventilated environments to collectively lower the risk of transmission. 

Another IHPC researcher, Dr Kang Chang Wei, said that in Singapore’s humid climate, large cough droplets will evaporate partially, leaving behind a smaller droplet which can then be carried even farther by the wind, and these factors were taken into account in the simulation. The research team worked closely with the National Supercomputing Centre, feeding a combination of physics and mathematical equations into a supercomputer to produce their simulation.

Credits to IHPC team: Dr Lim Keng Hui, Dr Kang Chang Wei, Dr George Xu, Dr Li Hongying, Dr Leong Fong Yew, Dr Ge Zhengwei.  

Visit Physics of Fluids to read the full paper.
The research work was also reported in The Straits Times on 9 Nov 2020.