Classroom: Covid 19 Airborne Risk Measuring

Description

This project investigates COVID-19 airborne transmission risk within a classroom setting using ANSYS Fluent, carried out through a full CFD analysis.

COVID-19 remains one of the most significant global health challenges, both due to its impact on human health and its high transmissibility between infected and healthy individuals. Breathing without a mask in an enclosed public space can transmit the virus to nearby occupants, which is why maintaining proper social distance has been a central recommendation from health professionals. In settings such as university lecture halls or school classrooms, the short distances between seated students can meaningfully increase the risk of transmission from an infected individual to those seated nearby.

This project simulates the breath of virus-carrying students within a classroom, with the goal of evaluating how effectively the room's ventilation system removes contaminated air. The modeled ventilation setup includes several fresh-air inlets positioned along the classroom ceiling, along with outlet panels located at the base of the side walls to allow stale air to exit.

The geometry was created in Design Modeler, representing a classroom populated with chairs, each occupied by a modeled student. For every student, a dedicated surface represents the mouth as the source of breathing and viral emission. The model was meshed using ANSYS Meshing, producing an unstructured mesh of 2,745,511 cells.

Methodology

This simulation uses the Discrete Phase Model (DPM), which allows a mass of particles to be studied discretely within a continuous fluid — in this case, air. The discrete phase representing virus particles is defined within a steady-state solver framework.

Once the discrete phase model is activated, the injection parameters are defined to specify the type and behavior of the particles introduced into the classroom. Virus particles are modeled as inert, with a surface-type injection applied at each student's mouth.

Boundary conditions for the discrete phase are set to Escape at the classroom's outer boundaries, allowing particles to exit the domain, while Trap conditions are applied to the students, chairs, and classroom walls, causing particles to accumulate upon contact with these surfaces.

Conclusion

The simulation results include particle tracking of virus particles based on a 60-second residence time, along with 2D and 3D temperature and air velocity contours, and 3D flow pathlines throughout the classroom.

The findings indicate that the installed ventilation system is poorly suited to the classroom environment and actually increases the risk of virus transmission — the virus particles are shown to disperse widely throughout the room's interior rather than being effectively removed, suggesting that the ventilation mechanism inadvertently helps sustain airborne viral presence within the space.