Highlight
IGERT Trainee Engage in Fundamental Research on Aerosol Transport in Indoor Environments
IGERT Trainee Brent Stephens using state-of-the-art aerosol instrumentation.
Achievement/Results
During the past year, trainees and affiliates of the National Science Foundation’s (NSF) Integrative Graduate Education and Research Traineeship (IGERT) program in Indoor Environmental Science and Engineering at The University of Texas (UT) have been involved in fundamental research related to aerosol transport in indoor environments. This includes research on particle resuspension from indoor surfaces, advancement of particle dispersion modeling, and studies related to exposure to particles from different sources.
Particle resuspension is the process by which particles are removed from surfaces, and resuspension indoors can increase exposure to allergens and other contaminants. Some earlier research on resuspension was conducted by IGERT affiliate alumnus Catherine Mukai who investigated the impact of air velocity and flow turbulence on particle resuspension. She developed methods for determining the number of resuspended particles for a given set of experimental conditions. Her results show that, beside velocity, turbulence has a very large impact on resuspension rates. This work was continued by IGERT trainee Brandon Boor, who developed a novel technique to investigate particle resuspension of monolayer and multilayer particle deposits. Using fluorescence stereomicroscopy to count particles before and after exposure to the flow in a wind tunnel, he found that resuspension occurs at significantly lower velocities for multilayer deposits compared to monolayer deposits. These findings explained the order of magnitude difference in resuspension rates measured in experiments conducted in wind tunnels and in the field. Both Catherine’s and Brandon’s results are important findings that fill gaps needed for accurate modeling of particle resuspension.
Further dispersion of resuspended particles depends on particle properties and airflow. The initial research in the field of particle dispersion was conducted by IGERT Affiliate alumnus, Donghyun Rim, who used experiments with thermal manikins and particle modeling to study transport of particles in the vicinity of the human body. He characterized the impact of thermal plumes on human exposure and developed guidance for assessment of human exposure to particulate matter from different source positions. Recently, a new grant from the American Society of Heating, Ventilating and Air Conditioning Engineers (ASHRAE) was awarded to UT researchers to continue these efforts. IGERT affiliate Shichao Liu and two faculty participants are involved in this research titled “CFD Resource Decision in Particle Transport Modeling.” The study will provide the engineering and research community with a validated methodology suitable for modeling of disease-bearing particles in the near vicinity of humans. The method is designed to be widely applicable to the transport of disease bearing particles associated with human respiratory processes such as breathing, talking, coughing and sneezing. The result will be a robust tool to study transport of infectious particles and person-to-person exposure. It should help building designers and other professionals to design or maintain healthy and safe indoor environments. The fundamental research on particle resuspension and dispersion at UT will be extended with more applied research where these models are used by IGERT trainees and affiliates for exposure analyses. Specifically, Brandon Boor will use these models to characterize the emission of particulate pollutants in the sleeping microenvironment and to investigate how the airflow around a sleeping human body transports pollutants from bedding materials to the breathing zone.
Address Goals
The research focuses on novel findings related to particle emissions and transport, and therefore discovery. Based on this research numerous journal papers have been published and several more are in the publication process. However, the project also has a strong learning component. The IGERT trainees and affiliates involved in experimental work and model development have to learn about novel experimental methods and explore fundamentals of fluid dynamics and particle transport. Also, IGERT trainees that apply particle modeling for human exposure studies learn about computational fluid dynamics (CFD) and particle modeling.
