Shield Effect on Coronavirus Particles Transmission

Description: Face shields have become a widely adopted protective measure in situations where maintaining full social distance isn't practical, but their actual effectiveness at blocking respiratory droplets during ordinary conversation is not always intuitive from visual inspection alone. This study uses computational fluid dynamics to examine that question directly, simulating how virus-laden particles expelled during speech behave when a face shield is present, and whether it successfully intercepts those particles before they can reach another person nearby. The scenario is deliberately set at a distance closer than standard social-distancing guidelines recommend, representing a realistic close-proximity interaction such as a conversation at a counter or a brief face-to-face exchange, in order to test the shield's protective capability under a challenging rather than ideal scenario.

Methodology: The 3D domain (1.6 m × 2 m × 2.6 m), built in Design Modeler, represents two individuals facing each other at 80 cm, with one designated as infected and their mouth acting as the source of viral particles during speech. The domain is meshed in ANSYS Meshing with 724,076 elements, and given the time-dependent nature of particle dispersion, a transient solver is used with a 0.001 s time step. The Discrete Phase Model tracks inert particles of 1 µm diameter released at body temperature (310 K) from the mouth over 0-20 seconds, driven by a sinusoidal velocity profile peaking at 0.33 m/s with flow rate scaled proportionally; an escape condition is set at the mouth to allow emission, while a trap condition on the shield surface captures incoming particles, and the RNG k-epsilon turbulence model is used alongside the energy equation to resolve flow and temperature behavior.

Analysis: Particle tracking visualizations across the 20-second simulation, colored by residence time and velocity, show particles accumulating on the shield's inner surface rather than reaching the second individual, confirming that the shield effectively intercepts droplets expelled during speech. These results support the shield's role as a protective barrier in close-proximity interactions where maintaining full social distance isn't practical.