Numerical Simulation of Aerosols Transmission due to Cough in an Indoor Environment Related to COVID-19

Abstract

COVID-19 pandemic has claimed many lives around the world, and it poses a substantial threat to public health and the workplace. Covid-19 outbreak has highlighted the dangers of virus transmission through the air. The most common place is hospital rooms where thei is greater risk of of virus spreading. When an epidemic strikes, the exponential increase in the number of patients has a disastrous effect on the medical system. About 600 million have been reported in worldwide which shows that hospitals are not a safe place to be. There are different mode of transmission from where the virus can infect a normal person. The most prominent being the aerosols transmission which has a huge impact on the health of a person. Different techniques has been addressed to mitigate the effect of Covid-19 disease. One of them is using CFD analysis which is the research focus of this thesis. In this research, computational fluid dynamics (CFD) simulation inside a hospital room is done to obtain a better comprehension off aerosols transmission. A three-dimensional Euler–Lagrangian model is utilized in this study to gain a better understanding of micrometer-sized droplet transmission and evaporation with and without ventilation. User defined functions (UDFs) have been used for turning on the ventilation. It is indicated that if the fan is turned off the airflow is not constant. Further the residence time of droplets tells us droplets reaching is slower in ventilation as compared to non ventilation case due to re-circulation. After evaporation some droplets are deposited on different surfaces which indicated that surfaces should be sanitized before entering into the room. At 6m/s, 5% of the aerosols has reached the outlet as compared to the other ventilation speeds, which shows at higher speed more more particles leaving the room. In a living room, the distribution of aerosols is studied in where the heavier droplets are located at the bottom side, and major part of the droplets are evaporated inside the 0.5 sec and the droplets become dry nuclei as they travel further down and after 7 sec, all droplets fall to the ground due to gravity. In the v case of ventilation, the droplets fallen to the ground leave the living room at 13 secs. Hence, it shows that for a complete removal of aerosols which ventilation is required. Which can greatly reduce the danger of virus transmission among humans in a closed indoor environment.