mask seal. Both inhaling and exhaling were simulated with total flow rates $F_{\mathrm{t}}= 30\, \mathrm{L/min}$ and $F_{\mathrm{t}}= 95\, \mathrm{L/min}$. In another set of simulations, below both eyes there was a gap with a circular-segment cross-section, with total gap width $B_{\mathrm{g}}=2.32\, \mathrm{cm}$ and average gap height $ H_{\mathrm{g}} = 1.45\, \mathrm{mm}$ as shown in Fig. \[FIG3DexhaleIsoU\]. Air was exhaled with total flow rates $F_{\mathrm{t}}=30\, \mathrm{L/min}$ and $F_{\mathrm{t}}=95\, \mathrm{L/min}$.

Results {#SECres}
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Figures \[FIGFt0Fg\]-\[FIGdp\] show results from 2D-flow simulations based on the setup from Sect. \[SECsetup\] for inhaling. The mask has a viscous porous resistance of $C_{\mathrm{m}}=2000\, \mathrm{m/s}$, corresponding to a mask that, when tightly fitted, produces a pressure drop $\Delta p$ close to the upper limit for a FFP3 mask according to the EN149 norm, i.e. $\Delta p < 100\, \mathrm{Pa}$ (for total flow rate $F_{\mathrm{t}}=30\, \mathrm{L/min}$) and $\Delta p < 300\, \mathrm{Pa}$ (for $F_{\mathrm{t}}=95\, \mathrm{L/min}$). Typical pressure drops measured in experiments for FFP2- and FFP3-masks were e.g. $97\, \mathrm{Pa} < \Delta p < 244\, \mathrm{Pa}$ (Jung et al., 2014) and $150\, \mathrm{Pa} < \Delta p < 230\, \mathrm{Pa}$ (Serfozo et al., 2017), indicating that the choice of $C_{\mathrm{m}}$ is feasible.

Flow rate $F_{\mathrm{t}}=30\, \mathrm{L/min}$\
![Analytical predictions and simulation results for 