Liepmann 逝世在physics today上的讣告

通流

这可是加州理工的大牛啊。统治了加州理工流体力学20多年。
其实当年钱学森在GALCIT的时候，李普曼可是排不上号的。

通流

Hans Wolfgang Liepmann, distinguished fluid dynamicist, outstanding teacher, and former director of the Graduate Aeronautical Laboratories at Caltech (GALCIT), passed away on 24 June 2009 at his home in La Cañada Flintridge near Pasadena, California.

Liepmann was born on 3 July 1914 in Berlin. After schooling in Germany, he moved to Istanbul, Turkey, where his father, a well-known physician, had accepted a professorship in order to escape the Nazis. A year later Liepmann went to Prague, Czechoslovakia, and quickly thereafter to Zürich, Switzerland. He obtained his PhD in physics from the University of Zürich in 1938 under Richard Bär. For his thesis, he used light-scattering methods to measure the speed of sound in liquid oxygen and other cryogenic fluids. Liepmann then accepted an invitation from Theodore von Kármán at Caltech and migrated to the US, joining GALCIT in 1939 just as the war that he had foreseen erupted in Europe. He took an immediate liking to Caltech and the US and stayed there for the rest of his life.

His research career at Caltech began with investigations of the stability of a laminar boundary layer. Liepmann confirmed Galen Schubauer’s detection of previously controversial instability waves at the National Bureau of Standards (now NIST) and reported interesting new results on curved surfaces. Much later, in 1982, he and Dan Nosenchuk would show, in an early example of active flow control, how those Tollmien–Schubauer waves (as Liepmann insisted on calling them) could be suppressed by suitably phased forcing.

As World War II was ending, Liepmann went on to look at transonic and supersonic flow. Pictures he and his students Anatol Roshko and Satish Dhawan took in his laboratory in 1952 were among the first to clearly demonstrate the nature of shock–boundary layer interaction. His spectral theory of transonic buffeting was a seminal effort on a real aeronautical problem. His enduring interest in turbulent flows began with a study of mixing layers, followed by careful experiments by students such as Stanley Corrsin, John Laufer, Roshko, and Donald Coles.

通流

With the advent of the space era, Liepmann’s interests moved toward o-hydrodynamics and rarefied gas dynamics. In the early 1960s he worked with Moustafa Chahine and me on the structure of a shock layer, using the Bhatnagar-Gross-Krook model within the shock. That work provided the first solutions that spanned the whole range of flow regimes from the continuum limit to large departures from local equilibrium. Liepmann’s later studies included the fluid dynamics of liquid helium.

From his unpaid postdoctoral beginnings at Caltech in 1939, Liepmann became a professor in 1949 and director of GALCIT from 1970 to 1985, when he formally retired as Theodore von Kármán Professor of Aeronautics. During his time as director, GALCIT emerged as the liveliest center in the world for basic fluid-dynamics research with a distinctive aerospace flavor.

Liepmann’s teaching was legendary at Caltech. His enthusiasm, ability to make nonobvious connections, and insistence on teaching without notes—except for a few “emergency” index cards carried in his pocket—made his classes very special. With Allen Puckett he wrote the path-breaking Introduction to Aerodynamics of a Compressible Fluid (Wiley, 1947). A more formal and definitive volume, The Elements of Gasdynamics, coauthored with Roshko (Wiley, 1957), taught the subject to generations of young students across the world. He also wrote some very readable short reviews that reflected his own incisive views of a subject; an excellent example is “The Rise and Fall of Ideas in Turbulence,” published in 1979 in American Scientist. More than 60 PhD students carried some of the spirit of Liepmann’s approach to fluid dynamics across the US and around the world.

Liepmann loved to tell stories about both big and small people from all over the world. His famous wit owed part of its charm to phrases lifted from “proper” English, delivered in a thick German accent. I recall his shouting down the corridor at a retreating student, “Have fun!” (But he also meant “Better work hard.”) He had strong likes and dislikes within and outside science. Among his favorite global leaders was the unlettered, tough, liberal-eclectic Mughal emperor Akbar the Great; we once went together to see Akbar’s failed capital near Agra, India, to the utter disgust of our taxi driver at being unable to persuade his “ignorant” customers to see the nearby Taj Mahal instead.

Among the numerous honors Liepmann received were the 1968 Ludwig Prandtl Ring of the German Society for Aeronautics and Astronautics, the 1986 Daniel Guggenheim Medal, the 1986 National Medal of Science, and the 1993 National Medal of Technology.

The world of fluid dynamics will miss a respected figure with a sharp mind, who looked at the subject with the critical eyes of both physicist and engineer, upheld the highest standards of research, and inspired hundreds of students to investigate the basic fluid flow problems that lurked behind modern aerospace technology.

onesupeng

其实当年钱学森在GALCIT的时候，李普曼可是排不上号的。”

这类话说得少一些比较好，钱老很好, L也很好。

通流

不管怎样，他写的那本书可是不错。中文版《气体动力学基础》是童秉刚翻译的吧。

onesupeng

五系很早有说编过《气体动力学基础》，也有说孔祥言老师遍过《气体动力学基础》，也有童先生编的《气体动力学》，不太清楚哪个版本是翻译的，但感觉是在建校之初的讲义发展而来的。

通流

在气体动力学方面的两本经典教材都是50年代的。一本是53年出版的Shapiro的《可压缩流动的热力学与动力学》另一本是57年出版的Liepmann与Roshiko的《气体动力学基础》，而这本57年的教材是在49年的Liepmann写的书的基础上写的。
后来的所有关于气体动力学的教材都是参考这两本书写的。而且以我的看法，都不如那两本好。所以，其实人们没有必要再写什么教材。
就有点像《热力学》，所有的《热力学》，特别是《工程热力学》都在抄Keenan在1943年出版的《热力学》。只有化工系的热力学，及物理系的热力学有点不同。

周华

教科书还是需要作者沉淀积累到一定程度才能写出好作品，否则写出来的东西都难免捉襟见肘。

通流

我说的只是当时的情况。至于谁好谁不行，每个人心中都有一个尺子。我要评论的话，也只是我的意见。

通流

写点我对李普曼的评价吧。对于他的学术，我不做评论。因为他做的很不错，我也没有读过多少他的论文，只是他的那本书是一直带在身边。

自从李普曼掌管GALCIT后，普朗特，冯卡门的那种理论为实践服务，理论与实际的完全结合的传统就开始丢失了。李普曼特别强调基础研究。强调基础没有错，但一旦脱离了实际应用，基础研究也就会慢慢地失去生命力。这也就是美国流体力学界目前的状况。Lumley 在annual review 呼吁流体力学家要加强与大众的交流，让大众明白流体力学的重要性。这实际就是当搞流体的人都钻到学术的象牙塔后的情形。

周华

那赶紧把Lumley请到我们论坛来，我们这里非常愿意跟大众交流，哈哈！

onesupeng

原帖由 通流 于 2010-3-10 13:08 发表

                               
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写点我对李普曼的评价吧。对于他的学术，我不做评论。因为他做的很不错，我也没有读过多少他的论文，只是他的那本书是一直带在身边。

自从李普曼掌管GALCIT后，普朗特，冯卡门的那种理论为实践服务，理论与实际的 ...

老表比较喜欢高屋建瓴地来几句。但我认为，这不是哪个单位的流体力学问题，而是目前整个流体力学学科的问题。上个世纪前半叶流体力学的发展有其重要的需求背景，在当时的情况是空气动力学的局限性是主要矛盾，而现在不是，大飞机预算里面空气动力学也仅仅是颗芝麻而已，虽然说的有点夸张，但情况是这样的。

通流

你还有大飞机的预算数据。空气动力学有多少？

其实，飞机的机翼一直是最关键的一个部分。而机翼的性能主要是气动。空客曾经说他们的机翼的气动特性比波音的好。在美国，气动比较成熟，这还有点靠谱。我国怎么会跟着老美呢？我们按理说真是应该发展的时候啊。

wqc1235

童先生的书现在都已经不出版了，挺可惜的