John Leask Lumley, the Willis H. Carrier Professor Emeritus of Mechanical and Aerospace Engineering at Cornell University who made seminal contributions to the physics and engineering of turbulent fluid flow, died from brain cancer on 30 May 2015 in Ithaca, New York.
John was born on 4 November 1930 in Detroit, Michigan. His lifelong appreciation of engineering design was encouraged by his father, an architectural engineer. John received his BA in engineering sciences and applied physics from Harvard University in 1952. He earned his master’s in 1954 in mechanical engineering and his doctorate in aeronautical engineering, under Stanley Corrsin, in 1957, both from the Johns Hopkins University. In 1959 he joined the Pennsylvania State University, where he rapidly rose to be the Evan Pugh Professor of Aerospace Engineering in 1974 at age 44. He was the youngest to ever hold that prestigious title.
At Penn State, John developed his unique style as a theoretician, modeler, and experimentalist. In 1977 he accepted an offer from Cornell University. He, his wife, and their three children moved into a rambling old Victorian home with a pond. They renovated the kitchen and thus could pursue their love of cooking and food, which began during John’s first sabbatical to Marseille, France, in 1966. Ithaca provided physical beauty, and Cornell offered John intellectual challenge and enduring friendships.
It is difficult to think of a facet of turbulence, whether it is formal mathematical theory, fundamental physics, or engineering and environmental applications, to which John did not make seminal contributions. Although others may have probed as deeply, we can think of no other who has covered the whole gamut, from Hölder continuity to hotwire circuitry. In each sphere John’s reach was broad. On the applied side, he wrote on drag reduction, buoyant plumes, gravity wave–turbulence interaction, turbulence in the presence of stable stratification, and the effects of electromagnetic fields on turbulence, among other things. He even wrote a paper on flow through a teat canal in a dairy cow.
John’s fundamental contributions span mathematics, stochastic processes, spectral dynamics, and the dynamics and modeling of all the generic flows. He pioneered the proper orthogonal decomposition approach that unambiguously extracts structures from turbulent flows, which though random contain structures that occur repeatedly, and orders them according to their energy content. That approach provides a mathematically optimal description that can be used to construct low-dimensional models of the flows.
With his students, he made several experimental contributions to the understanding of atmospheric turbulence, particles in turbulence, and shear flows. In 1990 he received the Fluid Dynamics Prize from the American Physical Society.
John was also a great educator. Although not known as a colorful lecture-room expositor, he influenced generations of students through his six books, his papers, and his films. His pathbreaking book A First Course in Turbulence, written with Hendrik Tennekes (MIT Press, 1972), was the first book to place dimensional analysis and scaling arguments as central to the subject. He had a lifelong passion for rebuilding old cars and wrote Still Life with Cars: An Automotive Memoir (McFarland & Co, 2005). He also provided editorial services to the Annual Review of Fluid Mechanics for 30 years, 19 of them as coeditor.
During the Cold War, Soviet scientists had developed turbulence theory and experiment significantly further than their counterparts in the West. John brought their advances to the attention of Western scientists by editing English translations of the two-volume treatise Statistical Fluid Mechanics: Mechanics of Turbulence, by Andrei Monin and Akiva Yaglom (MIT Press, 1971, 1975), and the Izvestiya, Atmospheric and Oceanic Physics journal series of the Soviet Academy of Sciences. After he caught the Soviets’ attention with his 1964 book with Hans Panofsky, Structure of Atmospheric Turbulence (Wiley), John’s work garnered much admiration in the USSR. He made several trips behind the Iron Curtain and met many prominent Soviet scientists.
John’s writing style was, like the man, idiosyncratic and hard to pin down. It was both rigorous and intuitive. While the prose was elegant and often amusing, there was sometimes a sketchiness that reflected, no doubt, his impatience. He worked quickly and didn’t look back. Some of his best papers were only one or two pages long. And his output was prodigious. Despite having strong views on the intellectual course of a subject, he was always ready to recognize innovative approaches and findings; he often used the word “cute” to describe something that particularly appealed to him. He was ready to drop pet theories if they did not measure up observationally.
However well one knew John, it was difficult to take him for granted; he was rarely spontaneous and was reticent in public. It was clear that he was intellectually special, never the one to toe the line of authority. Not only his long-standing colleagues but all of us in the field of turbulence will miss him greatly.
