Characterization of the aerosol produced from an aerated jet

Abstract

Faucet aerators that form aerated water jets generate aerosols, which can constitute a risk of infection if the water is contaminated, particularly for vulnerable individuals near the sink. In this study, we characterize the size and trajectory of water droplets produced from an aerated jet. The detected particle diameter ranged from 3 to 150μm. The concentration of droplets in the air varied from near-zero to a maximum of 2×10¹¹particles/m³, depending on the location relative to the jet. We found four relevant categories of droplets based on their trajectories following their emission at the jet's free surface: particles with inertia high enough to escape the immediate vicinity of the jet (category 1), particles moving towards the jet (category 2), particles drawn into the aerator, which only included particles with a diameter smaller than 50μm (category 3), and particles with a near-vertical trajectory (category 4). Tracing category 1 particles to their generation location on the water interface shows a higher emission rate near the aerator. Finally, we employ a numerical model to compute the subsequent trajectories of droplets detected at the limits of the sampled domain. We find that particles whose diameter is smaller than 55μm completely dry and become airborne. Larger droplets deposit within a radius of 7cm around the jet, assuming a surface is located 20cm below the aerator tip. These results increase the fundamental understanding of the emission mechanisms of droplets in aerated jets and their fate in the sink environment.

Keywords: Airborne transmission; Bursting bubbles; Faucet aerators; Particle tracking velocimetry; Phase Doppler anemometry; Sink environment.