Numerical study of different ventilation schemes in a classroom for efficient aerosol control

Area of Science:

• Environmental Science
• Fluid Dynamics
• Public Health

Background:

• Maintaining comfortable and healthy indoor environments is crucial.
• Air quality, specifically aerosol dispersion, is a significant concern in shared spaces like classrooms.
• Understanding aerosol transmission dynamics is vital for infection control and well-being.

Purpose of the Study:

• To analyze the trajectory and deposition of exhaled aerosols in a classroom setting under different ventilation scenarios.
• To compare the effectiveness of mechanical ventilation, natural ventilation, and no ventilation in controlling airborne particle spread.
• To investigate the impact of ventilation on aerosol evaporation, deposition, and exposure duration.

Main Methods:

• A multi-phase computational fluid dynamics (CFD) study utilizing Eulerian-Lagrangian techniques.
• Inclusion of parameters such as temperature, relative humidity, air velocity, direction, and pressure.
• Modeling of droplet evaporation, mass transfer, and turbulent dispersion.

Main Results:

• Mechanical ventilation demonstrated superior performance in controlling aerosol spread.
• Aerosols reached the front-row student within 0.5 seconds in all scenarios.
• Deposition on surfaces occurred faster with mechanical (2s) and natural (1s) ventilation compared to no ventilation (4s).
• Smaller particles (<20 μm) remained dispersed longer.
• Mechanical ventilation maintained stable humidity and reduced temperature, slowing particle evaporation.
• Energy losses were significantly higher with natural ventilation.

Conclusions:

• Mechanical ventilation systems are highly effective for managing airborne aerosols in classrooms.
• Ventilation strategies significantly influence aerosol exposure times and deposition patterns.
• CFD modeling provides valuable insights into indoor air quality and aerosol behavior for applications in medicine and energy engineering.