Cauchy’s almost forgotten Lagrangian formulation of the Euler equation for 3D incompressible flow
Cauchy’s almost forgotten Lagrangian formulation of the Euler equation for 3D incompressible flow
复制标题
柯西几乎被遗忘的 3D 不可压缩流欧拉方程的拉格朗日公式
DOI:
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发表时间:
2014
期刊:
影响因子:
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通讯作者:
B. Villone
中科院分区:
文献类型:
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作者:
U. Frisch;B. Villone
Abstract
Two prized papers, one by Augustin Cauchy in 1815, presented to the French Academy and
the other by Hermann Hankel in 1861, presented to Göttingen University, contain major
discoveries on vorticity dynamics whose impact is now quickly increasing. Cauchy found a
Lagrangian formulation of 3D ideal incompressible flow in terms of three invariants that
generalize to three dimensions the now well-known law of conservation of vorticity along
fluid particle trajectories for two-dimensional flow. This has very recently been used to
prove analyticity in time of fluid particle trajectories for 3D incompressible Euler flow
and can be extended to compressible flow, in particular to cosmological dark matter.
Hankel showed that Cauchy’s formulation gives a very simple Lagrangian derivation of the
Helmholtz vorticity-flux invariants and, in the middle of the proof, derived an
intermediate result which is the conservation of the circulation of the velocity around a
closed contour moving with the fluid. This circulation theorem was to be rediscovered
independently by William Thomson (Kelvin) in 1869. Cauchy’s invariants were only
occasionally cited in the 19th century – besides Hankel, foremost by George Stokes and
Maurice Lévy – and even less so in the 20th until they were rediscovered via Emmy
Noether’s theorem in the late 1960, but reattributed to Cauchy only at the end of the 20th
century by Russian scientists.