## 3 Results and Discussion
The performance of the masks was determined by evaluating the volume fraction of water at the wearer's face (water penetration per unit volume of mask). Figure 5d shows  
Figure 4: Mesh study using finite element analysis (the blue line represents the face mask profile). Figure 5: CFD simulations showing the velocity profile and the droplets size distribution from the source to the wearer while wearing masks. **(a)** Surgical (light blue). **(b)** Reusable cotton (black). (c) FFP2 (purple). **(d)** FFP3 (grey). **(e)** Antiviral (dark blue). **(f)** Silk (yellow). that the droplet's cloud at the _FFP3_ mask surface is less dense, and therefore, as shown in Figure 6, the volume fraction of water on the mask surface is low, as the F calculation shows (Table 2). This means that the _FFP3_ mask protects the wearer by filtering the majority of the particles. A similar result is shown in Figure 5c for the _FFP2_ mask. The droplet's cloud around the mask surface is sparse, meaning that the volume fraction of water at the mask surface is low (Figure 6). This means that the _FFP2_ mask is capable of blocking and filtering most of the airborne particles. In the surgical mask, the droplet cloud around the mask appears to be denser than the cloud near the _FFP3_ and _FFP2_ masks (Figure 5a). In fact, Figure 6 shows that the volume fraction of water near the _Surgical_ masks is higher than the cloud near the other masks. However, while not as effective as the _FFP2_ and _FFP3_ masks, the _Surgical_ mask is still capable of protecting the wearer from airborne particles. Surprisingly, the _Reusable Cotton_ mask can filter most of the 5 um particles contained in the air flow emitted from the source (Figure 5b). In fact, as shown in the graph in Figure 6, the volume fraction of water on the surface of the _Reusable Cotton_ mask is greater than the fraction present on the other face masks but close to the volume fraction present on the surface of the _Surgical_ mask. Finally, the _Antiviral_ and the _Silk_ masks show similar behavior (Figure 5e,f). The droplet cloud around the masks is very dense, meaning that both masks do not have adequate protection against airborne particles. In fact, the volume fraction of water on both mask surfaces is significantly higher compared to the volume fraction of water on all the other mask surfaces. Also, the simulation shows that the volume fraction of water when wearing a _FFP3_ mask drops significantly compared to the other five masks (Figure 6 (grey graph)). \begin{table}
\begin{tabular}{c c c c} \hline \hline
**Mask Type** & **V0 (m/s)** & **V1 (m/s)** & **Filtration Efficiency (F Total) \%** \\ \hline Medical-grade IIR Surgical & 38.55 & 1.56 & 88 \\ \hline Reusable cotton & 38.52 & 1.25 & 90 \\ \hline FFP2 & 39.02 & 0.46 & 96 \\ \hline FFP3 & 39.80 & 0.44 & 97 \\ \hline Antiviral & 38.42 & 1.75 & 86 \\ \hline Silk & 39.01 & 1.58 & 88 \\ \hline Without mask (Control) & 34.69 & 34.69 & 0 \\ \hline \hline \end{tabular}
\end{table} 
Table 2: Measured filtration efficiencies of the whole versions of each mask. Figure 6: The plot shows the different volume fractions of H\({}_{2}\)O at the wearer’s face when wearing different masks.