Description

This project uses ANSYS Fluent to simulate speech-driven release of coronavirus particles from an infected person and assess how face shields (or masks) block transmission to another individual. The 3D geometry is built in DesignModeler as a 1.6 m × 2 m × 2.6 m domain with two people facing each other at an 80 cm separation. The patient’s mouth is modeled as the emission source. Meshing is done in ANSYS Meshing (724,076 elements), and a transient solver is used to capture time-dependent particle dispersion.

Methodology

To study short-range propagation, the discrete phase model (DPM) is employed, treating expelled droplets as a discrete phase within a continuous airflow field. Unsteady particle tracking is enabled with a 0.001 s time step.

An injection at the mouth surface releases inert particles (diameter 1×10⁻⁶ m, temperature 310 K) from 0 to 20 s. A custom profile prescribes the particle exit velocity and mass flow rate during speech: the velocity follows a sinusoid peaking at 0.33 m/s, with flow rate proportional to velocity. DPM boundary conditions assign Escape at the mouth (particles exit through this boundary) and Trap on the patient’s shield/mask surfaces (particles are captured and accumulate there). Turbulence is modeled using RNG k–ε, and the energy equation is solved to obtain the temperature field.

Conclusion

Post-processing yields particle tracks classified by residence time and velocity. Consistent with the setup, particles are emitted periodically over the first 20 s. The shield causes expelled particles to deposit on its surface, preventing their forward transmission to the nearby person.