Characteristics of Droplet Transmission in Buses in Different Air Supply Modes

Abstract

In order to study the spread characteristics of virus droplets in the bus and predict the risk probability of airborne virus infecting passengers in the bus, a numerical model of the bus with the refrigeration and air conditioning on in summer is established based on the numerical simulation of computational fluid dynamics (CFD) in combination with the Wells-Riley equation. Through the analysis of the characteristics of the flow field in the bus in combination with the Lagrangian method, the spread process of the droplets produced by the cough of the virus carrier in the bus is calculated. The infection risk of virus-carrying droplets to the passengers in the bus in the four ventilation mades is analyzed. It is found that the longitudinal airflow in the bus is a key factor affecting the spread of droplets. Compared with the asymmetrically arranged circular air outlets, the longitudinal airflow in the bus can be reduced by the use of slit-type air outlets. Only 6% of passengers have a higher than 5% probability of contracting diseases in the bus with displacement ventilation, which is more effective in reducing the risk of droplet-borne infection. The research results can provide guidance for the structural design of bus air supply systems and reduce the risk of droplet-borne infections.

Keywords

• computational fluid dynamics (cfd)
• bus ventilation
• droplet spread
• wells-riley equation
• infection risk prediction