CFD Analysis of Coronavirus Transmission During Conversation Without Protective Barriers

This study presents a computational fluid dynamics simulation examining coronavirus particle transmission during face-to-face conversation at sub-optimal social distancing without protective equipment.

Model Development

A three-dimensional computational domain (1.6m × 2m × 2.6m) was created using Design Modeler software, representing two individuals facing each other at a distance of 80cm—below recommended social distancing guidelines. One individual was designated as infected, with their mouth serving as the source of viral particles during speech.

The computational mesh was generated using ANSYS Meshing software with 724,076 elements. Given the time-dependent nature of particle dispersion, a transient solver approach was implemented with time steps of 0.001 seconds.

Simulation Methodology

The Discrete Phase Model (DPM) was employed to track individual virus particles within the continuous airflow medium. Key simulation parameters included:

• Particle classification: Inert type
• Injection method: Surface-based emission from patient’s mouth
• Particle diameter: 1 micrometer (10⁻⁶ m)
• Particle temperature: 310K (body temperature)
• Emission duration: 0-20 seconds
• Velocity profile: Sinusoidal function with 0.33 m/s maximum velocity
• Flow rate: Proportionally linked to particle velocity

The RNG k-epsilon turbulence model was utilized alongside the energy equation to accurately capture flow dynamics and temperature distribution within the domain.

Results and Analysis

Particle tracking visualizations were generated at various time intervals throughout the simulation period, with particles colored according to residence time and velocity. The simulation captured two distinct phases:

1. Initial 20 seconds: Active emission of viral particles from the infected person’s mouth during speech
2. Subsequent 20 seconds: Continued movement of suspended particles through the air space between individuals

The results clearly demonstrated that without protective barriers, viral particles emitted during a 20-second conversation reached the healthy individual within 40 seconds of the interaction beginning. This confirms the high transmission risk during unprotected face-to-face conversations at distances below recommended social distancing guidelines.

These findings support public health recommendations regarding both social distancing and the use of protective barriers during interpersonal interactions, particularly in indoor environments where airflow patterns may contribute to particle transmission.