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Extended lifetime of respiratory droplets in a turbulent vapor puff

POSTER

Abstract

We numerically study a respiratory event with a turbulent jet together with 5000 exhaled droplets using a Lagrangian-Eurlerian approach. In our simulation, droplets are coupled to the ambient velocity, temperature and humidity fields such that we realistically account for the droplet evaporation in a respiratory event. In this study, we focus on cases with different ambient relative humidity (RH) with ambient temperature at $20^oC$ and exhaled vapor at $34^oC$. We found that for RH$=50\%$, the lifetime of the droplets with initial diameter of $10\mu m$ can be extended by up to 30 times as compared to the lifetime estimation by W. F. Wells (1934). The substantial increase in lifetime is attributed to the collective effects during droplet evaporation and the role of the respiratory humidity. The amount of lifetime extension even become more pronounced for larger RH, for example, the extension can go up to 200 times for RH$=90\%$. Our tool is a starting point for larger parameter studies, and our findings on extended lifetimes have implications on airborne disease transmission such as the pandemic of COVID-19.

Authors

  • Detlef Lohse

    Physics of Fluids Group, University of Twente and Max Planck Institute for Dynamics and Self-Organization, Universiteit Twente, University of Twente, Univ of Twente, Physics of Fluids Group, University of Twente, University of Twente, Enschede, Netherlands

  • Kai Leong Chong

    Physics of Fluids Group, University of Twente

  • Chong Shen Ng

    Univ of Twente, Physics of Fluids Group, University of Twente, University of Twente, Enschede, Netherlands

  • Naoki Hori

    Physics of Fluids Group, University of Twente

  • Rui Yang

    Physics of Fluids Group, University of Twente, University of Twente

  • Roberto Verzicco

    Univ of Roma "Tor Vergata", Gran Sasso Science Institute, Univ of Rome, Physics of Fluids Group, University of Twente, and Tor Vergata, Rome, University of Rome `Tor Vergata', Roma, Italy, University of Rome ‘Tor Vergata’, University of Twente & University of Rome, University of Rome "Tor Vergata"