A leader in wind tunnel technology
Jack E. Cermak, 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. He was 89.
His death was confirmed by his wife, Gloria Garza, who said he had suffered a stroke in 2006 and eventually became both blind and bedridden.
In 1959, Mr. Cermak founded the Fluid Dynamics and Diffusion Laboratory at Colorado State University, where he pioneered the use of a new kind of wind tunnel able to simulate the volatile air movements on the surface of Earth. Previous wind tunnels were built primarily to test airplanes and missiles and had wind coming in from only one direction and at a constant speed. By contrast, Mr. Cermak’s tunnel, which was roughly 10 times as long as aeronautical tunnels, could produce vertical wind currents and simulate powerful gusts.
Such a tunnel had been theorized about, but Mr. Cermak was able to envision how a large one could be built and pushed for it, said Jon A. Peterka, who taught with him at Colorado State and founded a wind dynamics consulting firm, CPP Inc., with Mr. Cermak in 1981. “He had an amazing view of the physical world in his head,” Mr. Peterka said.
Mr. Cermak’s tunnel — called an atmospheric boundary layer tunnel because it represented the layer of the atmosphere closest to Earth — changed the way buildings, bridges and other structures were built. Engineers could put a model of a structure in the tunnel and calculate the potential impact of wind on the design accordingly.
The first skyscraper design to be tested in this way was of the World Trade Center, in 1963. The resulting modifications were intended to enable the building to withstand gale-force winds.
After the collapse of the towers on Sept. 11, 2001, investigators looked into whether underestimates of wind forces had led to the use of weaker than necessary exterior columns that ultimately could not withstand the attacks by hijacked jetliners. Mr. Cermak vehemently rejected that view, and eventually it was widely agreed that it had been the intense heat from the explosions and fires caused by the planes’ impact that contributed the most to the buildings’ crumbling.
Mr. Cermak tested hundreds of projects using his tunnel, Mr. Peterka said, some of which involved buildings already constructed. After glass began falling from the Sears Tower in Chicago (now called the Willis Tower), Mr. Cermak placed a model in his tunnel and helped determine the cause, finding that it was not a design flaw but faulty installation of the glass.
Jack Edward Cermak was born on Sept. 8, 1922, to Joe and Helen Cermak, who ran a farm outside Pueblo, Colo. He served in the Army in World War II, achieving the rank of lieutenant colonel. He received a bachelor’s degree in civil engineering and a master’s in hydraulic engineering, both from Colorado State, before earning a Ph.D. in engineering mechanics from Cornell in 1959.
He founded the fluid dynamics laboratory that year and served as its director until 1985. He was president of CPP until 2006. He also founded the Wind Engineering Research Council in 1966 to disseminate technical information. It later became the American Association of Wind Engineering.
Until his stroke, Mr. Cermak remained absorbed in advancing wind dynamics, working full time until he was 84, according to Mr. Peterka, who said he could remember only two occasions when Mr. Cermak took a vacation of more than a few days.
“Jack had an image of where the discipline could go and spent his lifetime nudging us in that direction,” he said.