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Contemporary issues such as epidemics and the prevalence of infectious indicate that there is a pressing need to better understand the dynamics of transmission in air and facemasks. Consistent with previous literature, coronavirus disease (COVID-2019) is caused by the novel virus SARS-CoV-2. Coronavirus adds a new element to fluid fragmentation leading to respiratory droplets and which are transmitted via air during coughing, sneezing and talking. The behavior of virus-laden droplets of saliva particles arising from a human cough is described by Navier–Stokes equation for turbulent flow. The predicted velocity and pressure for droplets flow with time are presented. Hence, wall-normal profiles of velocity, pressure and concentration are obtained from boundary-layer approximations and the Navier–Stokes equations are solved on a two-dimensional shell mesh. The purpose of this study is to provide a perspective on the role of masks in the COVID-19 pandemic with an emphasis on the mechanism of droplet leakage and the droplet dispersion in this masks medical non-pharmaceutical intervention.

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This study examines the unsteady permeation process of a solvent through a mixture of two immiscible polymers with a complex dividing interface. The mathematical model consists of three nonlinear PDEs that incorporate the coupling arising between mass transport and the dynamic changes of the blend internal structure. In addition to the solvent mass fraction c, we choose, as additional state variables, the conformation tensor m to characterize the macromolecular chains while the embedded interface is described by a scalar Q and a traceless second-order tensor q respectively for the size and shape anisotropy of the area. We extend the Fick's first law by two new non-Fickian terms. Among the obtained results, we present the transient permeation mass flux profiles of toluene through PP/NBR blend system at different compositions and predict the corresponding time lag.