Computational and Experimental Techniques for Human Health and Security in Indoor Environments
Web Address: http://sumagazine.syr.edu/summer07/features/feature2/index.html
This material is based upon work supported by the United States Environmental Protection Agency under Award Number(s) EPA 05 X-83232501-0.
The primary goal of the proposed project is to develop tools that allow for technology innovations to create new Intelligent Environmental Quality Systems (i-EQS) for improved health and security in indoor environments. The specific objective is to develop experimentally validated computational tools for predicting the airflow and transport and migration of aerosols in the indoor environment. The study will be focused on assessing personal exposure due to exchanges between the breathing zones of occupants in indoor environments. This will be done with the use of the developed computational tools and particle image velocimetry (PIV) measurements at the Indoor Flow Lab (IFL) at SU. The IFL will be configured with two breathing thermal mannequins seated at a table in a cubicle. The computational models will be capable of handling all relevant scales. These models will be based on advanced direct numerical simulations (lattice-Boltzmann method), large eddy simulations and advanced unsteady RANS models. For particulate transport and deposition both Lagrangian and Eulerian formulations will be implemented. In addition, lower order models based on the proper orthogonal decomposition will be developed.
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These tools will provide the basis to develop real time prediction and control systems for intelligent built environmental systems to improve human health as well as for increased security.
The experimental PIV measurement concerning the airflow in the cubicle and in particular in the breathing zone of a sitting manikin sitting at Syracuse University has been completed. It was shown that the airflow is highly three dimensional in the breathing zone. Experimental study with a heated manikin was also performed. It was shown that the heated manikin will generate a thermal plume that leads to flow that could entrain particulate matters and bring them to the breathing zone region.
Our earlier studies were focused on isothermal conditions inside the cubicle containing a seated manikin. At present, the manikin was modeled by an assembly of rectangular blocks. Since July, we have been working on simulations in which the manikin is heated. The thermal plume above the manikin appears to be quite effective in preventing deposition of 2 micron and 10 micron sand particles that we release in the floor vent in front of the manikin.
The RANS simulations results were obtained for two manikins sitting across from each other in a room. Airflow conditions as well as particle trajectory were simulated for the mixing displacement ventilation air conditioning systems. The effect of evaporation on the transport, dispersion and deposition of emitted droplets was also investigated. Some preliminary simulations for a heated manikin in the room were also performed.
We have developed a recursive algorithm for finding the POD eigenmodes and eigenvalues. With the new technique, we can find eigenvalue spectrums that smoothly decay to machine zero even for problems with 16 (or more) orders of magnitude difference in eigenvalues.
Some preliminary results were reported at the ISTP-20 Conference in Victoria, BC last July (McLaughlin et al. 2009). A talk presenting the results shown above was given by John McLaughlin at the AIChE Annual Meeting in Nashville, TN on Nov. 10, 2009.
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