Numerical investigation of the role of human motion in the spread of virus-laden droplets from coughing using CFD dynamic mesh technique

Abstract

The transmission of viruses through the air plays a crucial role in the spread of viral diseases in enclosed environments. The mobility of individuals is a potential factor that contributes to the increment of the propagation of respiratory infections through the air. This research comprehensively focuses on transient modelling of the spread of solid-containing droplets during a cough from a moving person inside a ventilated room through CFD approach. This study investigates a range of moving speeds, from 0 to 1.5 m/s, to illustrate differences in patterns and concentration of droplets during both mobile and stationary conditions of an individual considering the interactions among gas, liquid and solid phases. Interactions between phases are considered through a coupled Eulerian–Lagrangian approach, and discrete phase model (DPM), turbulence model, species transport model, evaporation model and dynamic mesh technique are integrated. Moreover, the influences of effective forces such as buoyancy, Brownian motion, drag, lift, and gravitational forces are included. Regarding the results, motion of individuals significantly affects the airflow pattern and dispersion of droplets, particularly for walking speeds of more than 1 m/s. The results also elaborately indicate that person’s movement (from 0 to 1.5 m/s) considerably enhances the turbulent intensity (about 40 %), average air velocity and oscillations in pressure distribution, especially, pressure gradient before and after the moving person (about 1.5 Pa). Additionally, when the person walks at speeds exceeding 1 m/s, most of the particles cannot attach to the person’s body due to insufficient time for settling, resulting in an increment in the total number of particles that remain suspended in the air.