Country’s first lab tornado whirls inside ISU simulator

Saundra Myers

A mighty cyclone will soon rage safely within in the confines of Howe Hall.

ISU researchers led by Partha Sarkar, associate professor of aerospace engineering, have developed the nation’s first moving tornado simulator, an innovation that could improve understanding of tornadoes and lead to tornado-resistant structures.

The simulator is in the final stages of construction, and the team will start testing this week, Sarkar said.

“This is a valuable national tool,” said Fred Haan, assistant professor of aerospace engineering. “The simulator at Iowa State is unique — it’s the only one that moves.”

The simulator consists of a hollow cylinder 18 feet in diameter and 12 feet high with an inner fan six feet across. The simulator hangs from a five-ton crane above a test platform, called a ground plane, which is 36 feet long and 20 feet wide.

The ground plane can be raised and lowered with respect to the laboratory floor to change the height from the base of the cylinder, allowing for different-sized vortices, which are the centers of tornados, Sarkar said.

The simulator moves on the crane down a track to mimic a real tornado in a controlled environment, said William Gallus, associate professor of geological and atmospheric sciences.

The top speed of the vortex is approximately 55 miles per hour, with an average tornado moving at 110 miles per hour, Haan said.

The plane of the simulator will have different textures depending on what type of area researchers are examining. There will be landscapes built to scale representing areas of interest to measure the effect of the terrain on the vortex — ranging from urban to rural areas.

The moving tornado simulator is better than previous simulators and wind tunnels because it is more realistic, Sarkar said. The simulator’s large size allows models to be built on a bigger scale, making the simulated damage more lifelike. In a real tornado, the wind flow at a tornado’s vortex is not symmetric near the ground, Sarkar said. A larger simulator can demonstrate the same effect.

The simulator will give researchers a bigger picture of what happens near the vortex during a tornado, Haan said.

“What is going on near the ground, the interaction of the wind and the structure is what we are looking at,” Haan said. “The simulator will give a more realistic picture of the wind flow from the vortex to the structure.”

The project was started a year ago with a three-year, $300,000 grant from the National Science Foundation. The simulator is located in the Wind Simulation and Testing Laboratory in Howe Hall.

Sarkar said he got the idea for the tornado simulator when he came to Iowa State from Texas Tech University. He approached other researchers with his idea, and they put together a proposal for the grant.

All of the researchers became interested in the project for personal reasons, Haan said.

Sarkar became interested in tornado research after seeing damage from tornadoes in Oklahoma in 1999 where 40 people died. Gallus said he has been fascinated by tornadoes and has chased storms for years. Haan said he was terrified as a child of tornadoes because of a video he saw in grade school.

The team has been working with Josh Wurman, the president of Binet and former professor of atmospheric sciences at the University of Oklahoma.

Wurman uses a “Doppler on wheels” to gather data from tornadoes. This type of radar, mounted on a truck or trailer, can be placed in the path of tornadoes. The mobility of the Doppler on wheels gives it an advantage over stationary radar, which must be pointed above building levels. The team at Iowa State uses Wurman’s data to verify data received from the simulator, Gallus said.

People feel helpless against tornadoes, Sarkar said. Although tornado shelters protect life, property is often destroyed by tornadoes. With the research gained from the simulator, the researchers hope to find a way to build stronger structures.

The research project has drawn attention from all over the country, Sarkar said. NBC Nightly News will be visiting in a few weeks to film and interview the team. National Geographic and the Discovery channel have contacted them as well.