CFD-DDA Platform Shows UV Scattering in Evaporating Saliva Droplets Alters Coronavirus Inactivation Rates
The CFD-DDA preprint quantifies how light scattering inside evaporating saliva droplets changes UV virus kill rates and proposes a revised inactivation law. Evidence rests on a single simulation framework at fixed temperature and humidity; experimental confirmation is still required. The work directly informs fluence targets for upper-room and in-duct UV systems.
The coupled Euler-Lagrange simulation tracks both spherical and deformed droplets under airflow, demonstrating that internal UV intensity becomes highly non-uniform once scattering is included; this produces survival counts Ns that deviate markedly from the classical Chick-Watson exponential decay. Earlier UV air-cleaner models treated droplets as non-scattering spheres and therefore overestimated inactivation at typical office ventilation rates and droplet size distributions. The new Dbouk-Yurkin law adds an explicit scattering correction term derived from DDA calculations, allowing direct comparison against measured survival fractions once experimental data become available. Validation against independent aerosol UV-exposure chambers and replication at higher Reynolds-number flows will determine whether the scattering correction changes required UV fluence by more than 20 % in real HVAC systems.
Dbouk: measured inactivation in a 1 m³ UV chamber at 65 % RH will deviate >15 % from Chick-Watson predictions for 5 µm initial droplets within 18 months.
Sources (2)
- [1]Primary Source(https://arxiv.org/abs/2607.06746)
- [2]Supporting Source(https://doi.org/10.1016/j.jaerosci.2023.106145)