If there are no mean air flows then short time scales ~ 15 minutes. For instance in C.Klettner (19Aug11), 20 micro-m droplets were only dispersed over a 2m area with turbulent mixing. But mixing on larger length scales -> further dispersion https://t
@greg_travis @mamasaurusMeg Here is a numeric simulation of dispersion with turbulence. https://t.co/QRUDNLS8pE
@DrSimonAshworth In Fig2C, we see that the 20 micrometer diameter particle spreads out over a 2m diameter in 1000s (20min), and about half of them hit the floor in 2000s (40m). This assumes no mean air flow, people are stationary & typical turbulence v
@DrSimonAshworth Without bulk air flow COVID is unlikely to be detected more than 4m from the source, especially with sufficient humidity and ventilation. https://t.co/7IBSi7houT https://t.co/vxOGT9Ep7h