Methodology for simulating air leakages of an N95 filtering facepiece respirator-A pilot study

Air leakages happen when a respirator cannot fit its user well. This paper presents a methodology to predict potential leakage locations for an N95 filtering facepiece respirator. In this pilot study, we assume that the respirator is impermeable. Geometry features of a large size headform and a 3M 8210 respirator were captured by a 3D scanner. Using finite element (FE) method, the interaction between respirator and headform models was modeled in order to obtain their deformed shapes and fitting positions. Using computational fluid dynamics (CFD) method, the air flow in the domain between the respirator inner surface and the headform frontal surface was simulated. Four situations, including the exhalation with nose, inhalation with nose, exhalation with mouth, and inhalation with mouth, were simulated separately. Results showed that the air leakage mostly happened at areas near the nasal bridge. It was also found that the pressure caused by the respiration was considerably low.