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Partha Sarkar, Aerospace Engineering, (515) 294-0719
Bill Gallus, Geological and Atmospheric Sciences, (515) 294-2270
Fred Haan, Aerospace Engineering, (515) 294-2884
Bridget Bailey, News Service, (515) 294-6881


AMES, Iowa -- Three Iowa State University researchers are designing and building a simulator that will create moving tornados. Their ultimate goal is to learn how to construct homes and other buildings or structures that better withstand the wrath of a tornado.

Partha Sarkar, the T.A. and Grace Miller Wilson Endowed Chair in Engineering and an associate professor of aerospace engineering and civil engineering; Bill Gallus, associate professor of geological and atmospheric sciences; and Fred Haan, assistant professor of aerospace engineering, are collaborating on the project.

"We are basically trying to build the first tornado wind simulator ever that has a 'translating tornado,'" Gallus said. A translating tornado is one that moves in a path similar to a real tornado.

Gallus said tornado simulators typically use a stationary vortex. The researchers believe that the wind loads on buildings struck by a moving, or translating, tornado may be significantly higher than those measured in traditional wind tunnel experiments.

This study will allow researchers to test the stresses from a moving tornado. According to Sarkar, previous laboratory simulators were designed only for meteorological purposes.

"The new simulator should directly help improve the safety to the general public," Gallus said. Sarkar added that building codes will eventually improve with the results from this research.

The team will be using data collected by "doppler on wheels" radars run by Josh Wurman of BITNET Inc., Boulder, Colo. This data should help them get an accurate idea of the actual wind velocity near the ground during a tornado for the purpose of evaluating the laboratory simulator.

Gallus is in charge of collecting full-scale wind speed data and numerically simulating wind flow near the ground. Sarkar is primarily responsible for designing the simulator and Haan and Sarkar will help with measurement aspects of the wind flow and wind loads.

Sarkar said 800 to 1,000 tornadoes occur annually in North America.

"Every year, on an average, 80 lives are lost and $850 million of property damage occurs in the United States due to tornados," he added.

The simulator will be built in Howe Hall and will be part of the College of Engineering's Wind Simulation and Testing (WiST) Laboratory. It will serve a dual purpose. With a flip of a switch, the simulator will generate a microburst (powerful downdraft) of wind. A second, more traditional closed-circuit wind tunnel, also being designed and built by Sarkar and Haan, will be part of WiST.

Tornados produced in the new simulator will have a vortex that is 4-feet in diameter. Sarkar said the vortex of the simulated tornado is expected to be very similar (except smaller) to the vortex of a real tornado. Their test platform will be 20 feet wide, 30 feet long and 20 feet high.

After testing the simulator, Sarkar said the team will put geometrically scaled models of low-rise and high-rise buildings, buildings with domed shaped roofs, and slender chimneys and towers in the vortex. They will then measure the surface pressures on the models to see how much wind loads they experience.

Sarkar said this data could be directly used to design buildings and other common structures that are "tornado-resistant."

The National Science Foundation provided the team with a three-year, $300,000 grant for the research.


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