Hans W. Liepmann, 94
Hans Wolfgang Liepmann, a pioneering researcher and passionate educator in fluid mechanics, passed away at the age of 94. Liepmann, the Theodore von Kármán Professor of Aeronautics, Emeritus, at the California Institute of Technology (Caltech), passed away June 24 at his home in La Canada Flintridge. Widely honored for his contributions to aeronautics, Liepmann came to Caltech in 1939 and was the third director of Caltech’s Graduate Aeronautical Laboratories (GALCIT), from 1972 to1985.
Liepmann came to the U.S. in 1939 after impulsively expressing an interest in “hydrodynamics” during a drinking party at the successful conclusion of his PhD defense. An offer from Theodore von Kármán led to a research position in experimental fluid mechanics at GALCIT, where Kármán was the first director. Liepmann’s first experiments, on boundary layer instability and transition to turbulence, were followed by investigations of various turbulent flows that are relevant to engineering application—a recurring theme throughout his career. With the entry of the U.S. into World War II, he began research on problems associated with high-speed flight, including transonic flight phenomena and interaction of shock waves with boundary layers on aerodynamic surfaces. This also marked the beginning of a longtime interaction with the Southern California aircraft industry. With Allen Puckett, he organized short wartime courses on high-speed aerodynamics for working engineers, resulting in their pioneering textbook, “The Aerodynamics of Compressible Flow.” It was followed in 1956 by “Elements of Gasdynamics,” with Anatol Roshko, which impacted a broader, mainly graduate-student following, and was translated into Russian, Spanish, and Japanese.
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