The Neumann-Michell Theory of Ship Waves

2012-08-05

报告内容简介：
The classical Neumann-Kelvin (NK) linear potential flow model of 3D flow around a ship hull
steadily advancing in calm water will be reconsidered, and a modified theory --- called
Neumann-Michell (NM) theory --- will be summarized. The main difference between the two
theories is that the line integral around the ship waterline that occurs in the classical NK
boundary-integral flow representation is eliminated in the NM theory. This elimination of the NK
waterline integral is achieved, in two steps, using (i) a consistent linear flow model (the NK theory
in fact corresponds to an inconsistent linear model) and (ii) a mathematical transformation (that
amounts to an integration by parts). Two other notable features of the NM theory are (i) a highly
simplified Green function (which makes it possible to compute the flow around a ship hull in a few
seconds on a PC), and (ii) a practical method for filtering short waves. The NM theory amounts to
a correction of the classical slender-ship approximation proposed by Hogner about 50 years ago.
The NM correction of the Hogner Approximation yields more realistic predictions --- notably of the
ship drag and the wave profiles along the ship hull surface --- in better agreement with experimental
measurements. In particular, the excessive oscillations (humps and hollows) of the wave drag that
occurs in the Hogner slender-ship approximation (and the related Michell thin-ship approximation)
are largely eliminated in the NM theory. This notable improvement requires no significant increase
in computational efforts.
 

报告人简介：
Dr. Francis Noblesse obtained an American PhD in hydraulics from the U. of Iowa in 1974, and a
French Doctorate in hydrodynamics from the U. of Nantes in 1984. He will soon retire from the
David Taylor Model Basin, where he has performed research in ship hydrodynamics for the past
thirty years. He also held positions at universities in the USA (U. of Iowa, Stanford Univ, MIT) and
in France (U. of Nantes and Poitiers). The results of his research work are reported in about 150
publications. His recent work has considered analytical relations for ship bow waves, analytical
verification of CFD predictions, and a modification -- called Neumann-Michell theory -- of the
classical Neumann-Kelvin theory of ship waves. He was chosen to deliver the Weinblum Memorial
Lecture in 2000.
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联系人：万德成 教授 Email: dcwan@sjtu.edu.cn