73th Annual Meeting of the APS Division of Fluid Dynamics (November 22, 2020 — November 24, 2020)

V0059: ON SECONDARY ATOMIZATION AND BLOCKAGE OF SURROGATE COUGH DROPLETS IN SINGLE AND MULTI-LAYER FACE MASKS

Authors

• Shubham Sharma, Department of Mechanical Engineering, Indian Institute of Science, Bengaluru, India
• Roven Pinto, Department of Mechanical Engineering, Indian Institute of Science, Bengaluru, India
• Abhishek Saha, Department of Mechanical and Aerospace Engineering, University of California San Diego, La Jolla, USA
• Swetaprovo Chaudhuri, Institute for Aerospace Studies, University of Toronto, Toronto, Canada
• Saptarshi Basu, Department of Mechanical Engineering, Indian Institute of Science, Bengaluru, India

DOI: https://doi.org/10.1103/APS.DFD.2020.GFM.V0059

It is well-understood that the usage of facemasks provides protection from transmission of viral loads through exhalation and inhalation of respiratory droplets. Although three-layer masks are advised for usage, many commonly available or homemade masks contain only single and double layers. In this study, we show through detailed physics-based analyses and high-speed imaging that high momentum cough droplets on impingement on single- and double-layer masks can lead to significant partial penetration and more importantly atomization into numerous much smaller daughter droplets, thereby increasing the total population of the aerosol, which can remain suspended for a longer time. The possibility of secondary atomization of high momentum cough droplets due to impingement, hydrodynamic focusing and extrusion through the microscale pores in the fibrous network of the mask has not been explored before. Interestingly, this unique mode of aerosol generation poses the risk of infection, as demonstrated in this work.