Liquid Droplets Dispersion Modelling of COVID-19 Carrier in a Confined Space with Minimal Airflow

Kor, Yann Shen (2021) Liquid Droplets Dispersion Modelling of COVID-19 Carrier in a Confined Space with Minimal Airflow. Final Year Project (Bachelor), Tunku Abdul Rahman University College.

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Abstract

Recently, in China a novel coronavirus emerged which contributed to a global pandemic. The virus, named severe acute respiratory syndrome coronavirus 2 (SARS‐CoV‐2), causes a health condition called coronavirus disease 2019 (COVID‐19). Transmission of COVID-19 depends upon various factors, including the number of droplets, their size, and their velocity during out flow transmission processes such as coughing, sneezing, and breathing. The sneeze droplet spray contains between 2000 and 5000 bacteria that emanate from your nose and mouth when you sneeze. A sneeze can travel up to 30m/s and a cough can travel 11.5m/s. The exposure range of an exposed sneeze can travel up to 8m with the smallest droplets carried in the end of a turbulent cloud. The largest droplets settle widely within 1 to 2m. This research analysed the flow pattern of the liquid droplet’s dispersion as COVID-19 carrier in the air within a confined space and penetration of the droplets though elevator. Numerical simulation of sneezing and coughing using finite element analysis carried out to analyse the characteristic of the droplets’ flow pattern being carried in the gas cloud after an expiratory event such as sneezing and coughing. Besides that, the distance of the liquid droplets contains COVID-19 viruses that spray out from human mouth also analysed. The computing structure of mouth is developed using the commercial finite element simulation software Ansys which utilizes the modules of fluid flow. The three-dimensional model is built with a cube mouth inlet of 0.03m×0.03m and an elevator room 2.1m×1.6m×2.2m act as confine space. Head, torse, arm and leg of individual also built. Reynolds-Normalisation Group (RNG) k-ε turbulent based on Reynolds–Averaged Navier–Stokes (RANS) is applied to this research. Lagrangian method is applied to particle momentum equation for this research to determine the force balance equation of motion of a single particle or group in order to obtain velocity and to integrate time and to also obtain a trajectory. The numerical study is considered with two cases of closed elevator door and opened elevator door. As the result, the numerical result discovered that as time progresses, greater droplets fall to the ground, and that the speed at which they fall is depending on the droplet size. Smaller droplets (less than 10m in diameter) stay trapped for prolonged periods of time. Besides that, the numerical results obtained showed that the elevator domain is fully penetrated at 2.0s for sneeze and 2.5s for cough in enclosed elevator but opened elevator door penetration distance only reach 1.8m of the elevator for both sneeze and cough.