Numerical simulation of virus diffusion in facemask during breathing cycles

Abstract

The recent SARS outbreak has spawned a major controversy concerning the protective performance of facemasks. The objective of this paper is to establish a mathematical model for describing the mechanism of viruses diffusion in a facemask during breathing cycles. In this model the mechanisms of the water vapor molecular diffusion, evaporation/ condensation, sorption/desorption of moisture by fibers, Brownian diffusion of the virus, filtration of virus, capillary penetration of the viruses with the liquid water and latent heat generation due to phase change are considered. Meanwhile, the theoretical predictions are compared with experimental data, and good agreement is observed between the two, indicating that the model is satisfactory. Also, the effects of structural and materials properties on virus transfer are investigated.

Rapid evidence summary on SARS-CoV-2 survivorship and disinfection, and a reusable PPE protocol using a double-hit process

“…• The penetration of UV across the multiple layers of an N95 FFR may vary from one model and manufacturer to another 25 . There is some limited evidence that the majority (approximately 90%) of captured aerosols occurs on the outer filter layer on an N95 FFR 26 . Therefore, providing a larger UV dose on the outside surface may be desirable.…”

Heat and sweat transport through clothing assemblies with phase changes, condensation/evaporation and absorption

“…This also implies that the evaporation rate depends upon the liquid water left and no evaporation occurs when W = 0. On the other hand, the absorption process of fibre in a wet environment is described by an evolutionary equation (Haghi 2003;Li & Zhu 2003;Fan et al 2004;Li et al 2005;Huang et al 2008)…”

“…where R f is the radius of fibre, and D f , the diffusion coefficient, may depend upon the water content (Haghi 2003;Li et al 2005) and…”

“…In all the previous works (Fan et al 2000(Fan et al , 2004Li & Zhu 2003;Li et al 2005;Huang et al 2008), the absorption by fibre is described by the evolutionary equation (2.12) with the Dirichlet boundary condition…”

“…(ii) In all previous works (Li & Zhu 2003;Fan et al 2004;Li et al 2005;Huang et al 2008), the fibre absorption was described by an evolutionary equation along the fibre radius with a saturated Dirichlet boundary condition on the surface of a single fibre. This implies that the absorption on the fibre surface is enforced to be in saturation immediately for a given relative humidity.…”