The connection between mask deformation and peripheral leakage

Due to the COVID-19 pandemic, the use of face masks has been adopted by the general public as an effective method to reduce transmission. Respirators such as the N95 are highly effective at mitigating airborne diseases if properly fitted. The limited supply of these respirators led the general public to turn to more accessible protection such as surgical masks and fabric masks. The effectiveness of these masks has been shown to depend strongly on the mask material and fit. However, the aerodynamics of face masks is still not well-understood. The billowing caused by the increased pressure in the region between the mask and the face during expiratory events alters how the mask fits on the face resulting in increased peripheral leakage. Direct numerical simulations of the flow dynamics of respiratory events while wearing a face mask can be used to quantify the distribution of the peripheral leaks. Here we present a novel model for porous membranes (i.e., masks) and use it to explore the fluid-structure interactions of realistic faces wearing a fabric face mask.  The mask deformation and resulting leakage jets generated from different types of faces are of particular interest. The current model can be used to inform the quantification of face mask effectiveness and guide future mask designs that reduce or redirect the leakage jets to limit the dispersion of respiratory aerosols.