Violent expiratory events: on coughing and sneezing

The droplets ejected by a cough pose a serious danger in disease transmission.

Respiratory events such as exhalations or  more violent coughs and sneezes are key in transferring respiratory diseases between infectious and susceptible individuals. We present the results of a combined experimental and theoretical investigation of the fluid dynamics of such violent expiratory events. Direct observation reveals that such flows are multiphase turbulent buoyant clouds with suspended droplets of various sizes. Our observations guide the development of an accompanying theoretical model in which pathogen-bearing droplets interact with a turbulent buoyant momentum puff. The  range of validity of our theoretical model is explored experimentally. Our study highlights the importance of the multiphase nature of respiratory clouds in extending the range of respiratory pathogens.

See paper:  Bourouiba, L., Dehandschoewercker, E. and Bush, J.W.M., Journal of Fluid Mechanics (2014) 
MIT News piece here.