The question is complex: how fast do various chemicals, especially those considered dangerous to human life, absorb into household surfaces and our environment?

An answer may be close at hand.

Dr. Homayun Navaz, a professor of Mechanical Engineering at Kettering and director of the Chemical Agent Fate Research Program funded by a federal contracting corporation, is drawing closer to an answer on how to deal with the absorption of dangerous chemicals into our environment. As the principal investigator (PI) on this project, which received initial funding in April 2005 of more than $2.9 million, he and his team have worked diligently on identifying how fast chemical elements seep into everyday items through the use of a mathematical simulation model. Based on the success of the project thus far, the program received additional funding in May of this year through the current U.S. Defense Authorization bill for $2 million.

The project utilizes computer mathematical modeling and simulation models to predict the dispersion and persistence of a chemical in their air and ground after release. Additionally, this model also determines how long a chemical remains active or dangerous once it is deposited. This mathematical modeling is proving to greatly enhance the ability to computationally simulate possible scenarios involving chemical releases and aid officials in taking preventative actions to protect soldiers and the general population.

The idea is to "protect human life," Navaz explained. This requires the conversion of highly technical science and experimentally validated mathematical modeling information into a usable tool for military organizations and the general public as they develop strategies and plans to protect people from chemical releases.

Thus far, the two types of modeling Navaz and his associates are working on-continuum and discrete-are progressing well during efforts to examine the absorption of chemicals into various surfaces, such as porcelain tiles found in many American homes. But what is most intriguing is that the team has expanded their models to include evaporation of droplets of varying sizes. "The evaporation model represents a probable scenario we might expect when a chemical is released," Navaz said, adding that in recent months he and his team have submitted three papers to the Chemical and Biological Defense (CBD) conference scheduled for Nov. 13-15 in Baltimore, MD. The expectation is to communicate current results to a wider audience interested in this project.

In recent months, the team has also had two important breakthroughs. The first is an ongoing research effort with Dr. M. Gharib of Caltech. Navaz said his team and Gharib have worked successfully to enable researchers to easily scale the outdoor scenarios using any wind tunnel environment. The second breakthrough allows the team to extend the model to include chemical agents without the need for laboratory tests on these agents, since tests are both difficult and expensive. Navaz said that these original findings will soon be published in journals.

The mathematical and numerical algorithm associated with this program allows researchers to incorporate new models in an easy and efficient manner, since the program is modular in structured. "The models allow us to input various fluid properties, which makes it more flexible in predicting how other liquids like pesticides and oil could penetrate surfaces. Now, with the incorporation of the evaporation model, we can more easily predict how liquids might evaporate on a surface, because the engine of this program doesn't require any modification to accommodate new models," he added.

Overall, Navaz is happy with the progress of this research and believes the results of this effort extend well beyond the scientific community. "The end result of these complicated modeling exercises," he said, "is that we will produce a simple-to-use product for end users to help predict the persistency of chemicals in the environment. And so our final product is very practical, especially since we're converting some of the most scientific concepts into a useful tool."

Navaz is also happy with the work of the team, which includes Dr. Matthew Sanders, associate professor of Industrial and Manufacturing Engineering, who overseas the work of the following co-op students: Chemistry Major Elizabeth Cox, from Monroe, Mich.; Senior Ewen Chan from Toronto, Ontario; Tevita Skeine from Flint, Mich.; Computer Science Major Aaron Grady from Chicago, Ill.; and Chemistry Major Carlos Rincon from Kalamazoo College. Dr. Ali Zand from the Chemistry Dept. is currently leading some of the team's experimental efforts with the assistance of Post Doctorate Fellow Dr. H. Li. The team also benefits from the work of Dr. Bojan Markicevic, another post doctorate fellow in the area of porous media.

Finally, Navaz ultimately hopes that using experimental data and these analytical tools will help the team to invent a solution to the complex question of how fast chemicals leech into household surfaces and our environment. As far as future goals, Navaz said that the idea is to make the approach to this complex question "very general and global, which would make it more applicable to a wide range of potential events," he said. "The more global our model is, the more useful our generated results will be when faced with future, unforeseen circumstances."

The above video is a plot of discrete modeling inside the pores of the chemical droplets. As readers can see, once the drop is absorbed into a porous substrate, it spreads in a wide pattern and impacts the surface of a substrate more comprehensively than the human eye can see.

The above simulation shoes the absorption of three different size droplets of a chemical into a porous substrate using the continuum modeling developed by Navaz and his team.

To learn more about this project, contact Dr. Homayun Navaz at (810) 762-9597.

Written by Gary J. Erwin
(810) 762-9538
gerwin@kettering.edu