id	author	title	date	pages	extension	mime	words	sentences	flesch	summary	cache	txt
cord-301721-31a2q3ad	Balachandar, S.	Host-to-Host Airborne Transmission As a Multiphase Flow Problem For Science-Based Social Distance Guidelines	2020-09-01		.txt	text/plain	16802	923	60	In this paper, we discuss the processes of droplet generation by exhalation, their potential transformation into airborne particles by evaporation, transport over long distances by the exhaled puff and by ambient air turbulence, and final inhalation by the receiving host as interconnected multiphase flow processes. But as the puff of air and the droplets move forward, the droplet Reynolds number rapidly decreases for the following reasons: (i) as will be seen in section 4.1 the puff velocity decreases due to entrainment and drag, (ii) as will be seen in section 4.2.1 the droplet diameter will decrease rapidly due to evaporation, (iii) as will be seen in section 4.2.2 the time scale τ V on which the droplet accelerates to the surrounding fluid velocity of the puff is quite small, and (iv) very large droplets quickly fall out of the puff and do not form part of airborne droplets. It should again be emphasized that the temperature difference between the puff fluid containing the droplet nuclei cloud and the ambient air may induce buoyancy effects, which for model simplicity will be taken into account as part of turbulent dispersion.	./cache/cord-301721-31a2q3ad.txt	./txt/cord-301721-31a2q3ad.txt