Computational Fluid Dynamics of Disease Transmission - MIT

Project Overview

This MIT research project uses advanced computational fluid dynamics (CFD) to explore the mechanisms behind disease transmission through respiratory droplets and surfaces. Working with the MIT Fluid Dynamics of Disease Transmission Lab, the project sheds light on how droplets containing pathogens behave in various environmental conditions such as temperature, humidity, and ventilation. This research is essential for creating robust strategies to limit disease spread in indoor spaces and crowded public environments.

CFD Analysis of Pathogen Transmission Phases

Phase 1: Pathogen encapsulation within droplets expelled during respiratory events like coughing or sneezing.

Phase 2: Transport of pathogen-laden droplets through turbulent multiphase flows, influenced by airflow and ambient temperature.

Phase 3: Pathogen survival on surfaces, where factors such as humidity and surface composition impact viability.

Phase 4: Reintroduction of pathogens to hosts via inhalation or surface contact, emphasizing the role of fluid-surface interactions.

Project Implementation

The experimental setup includes a custom Arduino-controlled chamber with sensors to monitor specific humidity and temperature levels, simulating real-life indoor environments. This setup enables controlled studies on the interaction of droplets with surfaces under different environmental conditions. CFD simulations complement the empirical data, allowing us to predict the behavior of droplets and aerosols across a range of airflows and surface types. The integration of CFD data with real-time measurements provides insights into optimal humidity and temperature levels to limit pathogen survivability on textiles and surfaces.

Arduino Chamber for Disease Transmission Study

Fluid Dynamics Insights

Leveraging CFD in pathogen transmission research involves analyzing complex, multi-scale fluid dynamics that govern the interactions between droplets and their environment. Key aspects include:

Multiphase Flow Modeling: Respiratory droplets, often encapsulating pathogens, are carried within turbulent multiphase flows. CFD captures the intricacies of droplet formation, transport, and evaporation, enabling simulations of both large droplet trajectories and the finer aerosols that can remain airborne for extended periods.
Interfacial Dynamics and Droplet Fragmentation: The breakup of respiratory droplets into smaller nuclei plays a critical role in aerosolized transmission. CFD models help understand how interfacial forces (e.g., surface tension) interact with ambient turbulence to create pathogen-bearing aerosols capable of traveling farther than larger droplets.
Reaerosolization from Surfaces: Pathogens on surfaces can re-enter the air through resuspension when disturbed. Understanding the role of airflow and surface properties in reaerosolization is essential for mitigating pathogen spread in high-traffic areas, particularly in healthcare settings.
Bursting Bubbles as Secondary Aerosol Sources: In specific environments, bubbles bursting on contaminated surfaces can release aerosols that contain pathogens, highlighting unique transmission risks in places like hospitals and wastewater systems. CFD analysis of bubble dynamics provides critical data for assessing these secondary risks.

Research Framework

The study uses a four-phase framework that isolates each stage of fluid dynamics involved in pathogen transmission, enabling precise analysis of droplet dynamics:

Phase 1 - Ejection: Pathogens are expelled within droplets during coughing or sneezing, with droplet formation affected by the respiratory mechanism. CFD simulations allow for detailed modeling of droplet ejection speeds, angles, and sizes to capture realistic expulsion patterns.
Phase 2 - Transport: Droplets travel in turbulent airflows, influenced by ambient temperature and humidity. CFD helps predict how these droplets behave over short and long distances, highlighting risks in confined indoor spaces.
Phase 3 - Persistence: Once settled on surfaces, pathogens face variable survival rates based on environmental factors. CFD offers insights into optimal humidity and temperature control to limit pathogen viability on different surfaces.
Phase 4 - Reintroduction: Pathogens may become airborne again through resuspension or interact with new hosts upon contact. This phase underlines the need for fluid-surface interaction studies to mitigate infection risks in high-touch areas.

Findings and Results

The experiments demonstrated that pathogen survivability on textiles is highly sensitive to environmental variables, particularly humidity and temperature. Lower humidity levels correlated with reduced pathogen viability, while elevated temperatures accelerated degradation rates. These results, validated through CFD simulations, suggest that precise environmental control can be an effective tool in reducing transmission risks in hospitals, schools, and public spaces.

Conclusion and Future Directions

This study underscores the critical role of CFD in understanding the transmission dynamics of airborne pathogens. The ability to simulate and predict droplet behavior at various environmental conditions aids in designing effective control strategies for infection prevention. Future research may extend this approach by introducing additional environmental variables such as ultraviolet (UV) exposure and exploring CFD applications in other pathogen-transmission scenarios, like those found in wastewater treatment or aerosol-generating medical procedures.