ABSTRACT
LEWY H. 20.10. 1904 Wroclaw/PL 23.08. 1988 Berkeley CA/USA Hans Lewy was born in the former German city Breslau, today’s Wroclaw in Poland. He completed his studies at Göttingen University, obtaining the PhD degree for a numerical boundary-value problem which was tutored by Richard Courant. He was in 1927 appointed Privatdozent, similar to a Reader, and in 1928 published with Courant and Kurt O. Friedrichs (1901-1982) the famous book on partial differential equations, including the fundamental CFL-condition as a numerical stability criterion for unsteady partial differential equations. Once the Nazis had taken power, Lewy was dismissed in 1933, so that he emigrated over France to the USA, where he was appointed professor of applied mathematics at the California Institute of Technology, Berkeley CA. Lewy was awarded the Leroy P. Steele Prize of the American Mathematical Society AMS in 1979, and the 1985 Wolf-Prize as a life-time achievement. Lewy was concerned all through his career with the analysis of partial differential equations, partly with applications to hydrodynamic problems. Of relevance was his 1946 paper, in which the shallow-water equations are applied before computers were available. This hyperbolic type problem requires the application of the CFL-condition. Progressive waves were studied in two dimensions thereby neglecting compressibility and viscous effects. Other papers involve problems of water flow, mainly of unsteady type, so that the governing equations remain more or less identical. It was stated that ‘Lewy’s work is… extremely original and inventive: He created many ideas which have opened new fields and are still waiting to be developed or extended in the future’. Courant, R., Friedrichs, K.O., Lewy, H. (1928). Über die partiellen Differentialgleichungen der mathematischen Physik. Mathematische Annalen 100(1): 32-74. Friedrichs, K.O., Lewy, H. (1948). The dock problem. Communications on Pure and Applied Mathematics 1(2): 135-148. Lewy, H. (1946). Water waves on sloping beaches. Bulletin of the American Mathematical Society 52(9): 737-832. Lewy, H. (1952). A note on harmonic functions and a hydrodynamical application. Proc. American Mathematical Society 3(1): 111-113. Lewy, H. (1952). On steady free surface flow in a gravity field. Communications on Pure and Applied Mathematics 5(4): 413-414. https://de.wikipedia.org/wiki/Hans_Lewy P
LIEPMANN 03.07. 1914 Berlin/D 24.06. 2009 La Canada CA/USA Following a PhD and a year as a research fellow at Eidgenössische Technische Hochschule ETH Zurich, Hans Wolfgang Liepmann joined in 1939 Caltech as a research fellow. He became in 1972 director of Caltech’s Graduate Aeronautics Laboratory GALCIT thus following two leaders in aeronautics, Theodor von Karman (1881-1963),and Clark B. Millikan (1903-1966). Liepmann was awarded in 1969 the Ludwig-Prandtl-Ring, the primary decoration of the Deutsche Gesellschaft für Luft-und Raumfahrt DGLR. He was further awarded the National Medal of Science in 1986, and in 1993 the National Medal of Technology. Liepmann was internationally known for his outstanding work in fluid mechanics and aerodynamics. He initially worked on laminar instability problems, the transition to turbulence and related topics. He then took interest in boundary layers along shock fronts and applied the results to high-speed aircraft design. Liepmann also investigated the direct measurement of local skin friction in both low-and high-speed flows. He did research in aerodynamic noise and turbulence, and in the dynamics of liquid helium. The latter work has furthered the understanding of fluid motion at low temperatures and thus opened possibilities for applications in energy storage and heat transfer. He also advanced a number of instruments to measure the characteristics of fluid flow. Anonymous (1960). Chairman S.A. Schaaf with the speakers. Aeronautics and Astronautics: Frontispiece, N.J. Hoff, W.G. Vincenti, eds. Pergamon Press: Oxford. P Anonymous (1972). Hans W. Liepmann. Astronautics and Aeronautics 10(6): 79. P Benecke, T. (1969). Überreichung des Ludwig-Prandtl-Ringes an Prof. Dr.phil. Hans W. Liepmann. DGLR-Mitteilungen 2(2): 7-8. P Coles, D., ed. (1988). Perspectives in fluid mechanics. Symposium held on the occasion of the 70th birthday of Hans Wolfgang Liepmann, Pasadena CA. Springer: Berlin. Liepmann, H.W., Laufer, J. (1947). Investigations of free turbulent mixing. NACA TN 1257. Washington DC. Liepmann, H.W., Dhawan, S. (1951). Direct measurements of local skin friction in low-speed and high-speed flow. Proc. 1st US Congress Applied mechanics Chicago: 869-874. Liepmann, H.W. (1952). Aspects of the turbulence problem. Zeitschrift für Angewandte Mathematik und Physik 3(5): 321-342. Liepmann, H.W., Roshko, A. (1957). Elements of gas-dynamics. Wiley: New York.
