Jack Cermak, 89, an engineer who was among the first to use a wind tunnel to gauge the wind's impact on skyscrapers and who did consulting work on the World Trade Center and the Sears Tower, among other projects, died Aug. 21 at his home in Fort Collins, Colo.
In 1959, Mr. Cermak founded the Fluid Dynamics and Diffusion Laboratory at Colorado State University, where he pioneered the use of a wind tunnel able to simulate the volatile air movements on Earth's surface. Previous tunnels were built primarily to test airplanes and missiles and had wind coming from only one direction and at a constant speed. By contrast, Mr. Cermak's tunnel, roughly 10 times as long as others, could produce vertical wind currents and simulate powerful gusts.
