Local control of near-field diffusion of infected respiratory cloud in a room by air-blades

Abstract

The respiratory cloud of an infective subject contains droplets of mucosalivary fluid carrying pathogens. As this cloud spreads at a certain distance from the emission point, the droplets accumulate and their volume concentration increases in the room unless dilution, adequate ventilation, or filtration reduce it. A susceptible subject, standing a short distance away can be exposed more easily to the infected respiratory cloud, thus inhaling a higher dose of pathogens than someone breathing the mixed air in the room. A local airflow pattern can be employed to reduce this short-distance risk of inhalation and potential contagion. We present experimental and numerical investigations of a novel device acting as a barrier to airborne pathogen diffusion at a short distance. This portable device generates V-shaped air blades in front of the subjects, shifting the respiratory clouds. The air blades are generated by 12 small fans, three on each side of the cube. The air is sucked into the small plenum inside the device body through the bases. By being positioned obliquely on a meeting table, the device acts as a direct barrier to virus-laden aerosols without any filtration. The experimental tests show that the system can reduce the local concentration of aerosol by 63 to 84% at the respiratory position of a subject sitting at a table in front of an infective person. CFD simulation outputs using the Multiphase Eulerian-Lagrangian model show a good agreement with the experimental results. The validated model will be used to extend the range of investigation to different settings and to perform a parametrical analysis of the main design conditions.