“Why do we have to be helpless?”

This is a question Partha Sarkar, associate professor of aerospace engineering and engineering mechanics, thought about when he went to do a damage survey in Nashville, Tenn. after a tornado struck the area in 1997.

Now, with the help of funding from the Department of Aerospace Engineering, Sarkar is working to make individuals less helpless against twisters.

With the assistance of other professors and graduate students, Sarkar is building the first moving tornado simulator. The goal of the simulator is to measure the wind loads produced by moving tornadoes on various structures.

“The final goal is to design a structure that can withstand tornadic wind fields to some extent, if not completely,” Sarkar said.

Sarkar said currently, there is no way to design a structure that can stand up to the strong winds produced by tornadoes because it is unknown what kind of wind loads act on the structure.

Old simulators were stationary, Sarkar said. This prevents those simulators from being able to predict the actual wind load of a translating tornado, which are likely to be more intense.

Current buildings are designed for straight-line winds, he said, not those of tornadoes.

The simulator is not only different from previous ones because it moves, but it is also much bigger in size, Sarkar said. The total dimension of the simulator is 20 feet wide, 43 feet in length and 19 feet high. A four foot vortex, or wind tunnel, will be generated.

The reason for the size of the structure is to test the effect of the moving vortex on scaled down models, Sarkar said.

Fred Haan, assistant professor of aerospace engineering and engineering mechanics, mostly works on the experimental part of the project.

Haan said it is not understood how the winds of a moving tornado interact with various types of buildings. “What we have seen from preliminary results is wind loads are bigger when the vortex is moving,” said Haan. “It makes it more realistic.”

Sarkar would like to see the results of the experiment used to make buildings more resilient to tornadoes. In the future, Sarkar said the results of the experiment could be used to improve building codes for both high-rise and low-rise structures.

Haan agreed. “We are quite interested in what these [wind] loads are going to be. Then we will compare them to building codes for various structures: residential, schools, power plants,” he said.

Sumeet Gupta, a graduate student in aerospace engineering and engineering mechanics, will work on the simulator until the end of summer. “The tornado is a very hard issue,” he said. “Iowa is a tornadic area. Nobody has done a lot of research on this.”

Gupta will be replaced in August by another graduate student.

Sarkar estimates the cost to build the simulator is $90,000. This is funded through his start-up fund he received when coming to Iowa State. He was formerly a professor at Texas Tech.

After the simulator is built, the National Science foundation will provide the team with a $300,000 grant over three years.

Sarkar hopes to finish the simulator by the end of the summer, although he said that time frame may be a bit optimistic.