The US east coast was just rocked by a 5.8 earthquake on Tuesday and is hunkering down for Hurricane Irene on Sunday. The only thing missing from this natural disaster trifecta: tornadoes.
The Tornado/Microburst Simulator at the Iowa State University College of Engineering is the largest tornado simulator on the continent. The simulator itself consists of a 5.5m x 3.7m (d x h) cylinder that houses a 1.8m fan. This apparatus is hung from a 5.4-tonne crane a metre above a 11m x 6m ground plane where the little model houses, landscape, shrubbery, or whatever else is being tested sits. Adjusting the ground plane's height in relation to the simulator allows researchers to change the size of the mini-tornado's 1.2m vortex. It can even generate two-cell tornadoes, similar to the F5 that decimated Joplin, MO earlier this year.
So why build a ground plane twice as long as the simulator? Because the Iowa State simulator isn't just the biggest in North America, it's also the only one that moves. The crane that supports the simulator assembly is mounted on a set of overhead tracks, allowing it to traverse the length of the ground plane and more accurately mimic the destruction actual tornadoes cause.
While the simulator's top wind speed is only about 90km/h — real ones get moving at about 180km/h — it should provide invaluable insight into the atmospheric conditions within a tornado's vortex (the eye of the storm, so to speak) and how it behaves. Until now, gathering data on vortices has been incredibly difficult — as tornadoes tend to tear up instruments placed in their path — and incredibly dangerous — as they tend to tear up researchers placed in their path as well (unless, of course, you're Bill Paxton).
Primarily, the system is employed to study how various types of terrain affect the flow of wind near the ground as well as how extreme wind loads affect a building's structure. The data gathered from these experiments is then used to develop sophisticated computer models that can accurately depict how the structure will fail and which parts will fail first. These models then assist engineers in building more aerodynamic, more wind-resistant buildings.
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