Simulating Fate and Transport of Expiratory Droplets
Transport and fate of human expiratory droplets play a key role in the transmission of respiratory infectious diseases. The dynamics of virus transmission is not well understood, with one challenge being the complicated fluid and flow characteristics involved in the fate and transport of virus, including source dynamics (e.g., exhale velocity and temperature, droplet sizes, virus load, and droplet–virus correlations), ambient conditions (e.g., mean and turbulent flows, temperature, and humidity), and virus dynamics (e.g., virus viability and infectious rate). Collaborating with experts in influenza virus transmission, we recently developed a fate and transport model to simulate droplet evolution during normal human respiratory activities (talking, coughing, etc.). We improve the model prediction by using a continuous random walk model to better characterize the correlated velocity fluctuations in these respiratory flows.
The simulation shows strong influences of ambient conditions, exhaled velocities and temperatures. The dispersion and evolution of droplets with different initial diameters have very different sensitivity to ambient environments. In the future, we will incorporate the correlation between droplets and viruses to understand the transport of viruses and the risks of exposure at different locations.