NUMERICAL DISPERSION MODELLING OF THE DROPLETS EXPIRED BY HUMANS

ABSTRACT

Owing to the COVID-19 pandemic, in the last two years the attention of the scientific community has focused on the study of the dispersion of small droplets ejected by humans during different respiratory activities. The properties of the droplets used as input data in numerical simulations and models that forecast the dispersion of the expired particle-laden air cloud are of major importance in order to obtain reliable results. Recent numerical simulations highlighted that a lack of knowledge concerning droplet size and velocity distributions still exists. Indeed, only few works tackled this problem, since it is particularly difficult to measure droplet sizes over a wide range and to measure sizes and velocities simultaneously. Consequently, the droplet velocity is generally assumed to be either zero or equal to the air velocity. In this work, the dispersion of droplets expired by humans have been simulated numerically using as input experimental data collected during two measurement campaigns concerning speaking and coughing. The size and the 3 velocity components of the ejected droplets have been measured simultaneously for particles down to 2 μm using an extended version of the Interferometric Laser Imaging Droplet Sizing technique. © British Crown Copyright (2022)