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Hamiltonian fluid mechanics is the application of Hamiltonian methods to fluid mechanics. This formalism can only apply to nondissipative fluids. ==Irrotational barotropic flow== Take the simple example of a barotropic, inviscid vorticity-free fluid. Then, the conjugate fields are the mass density field ''ρ'' and the velocity potential ''φ''. The Poisson bracket is given by : and the Hamiltonian by: : where ''e'' is the internal energy density, as a function of ''ρ''. For this barotropic flow, the internal energy is related to the pressure ''p'' by: : where an apostrophe ('), denotes differentiation with respect to ''ρ''. This Hamiltonian structure gives rise to the following two equations of motion: : where is the velocity and is vorticity-free. The second equation leads to the Euler equations: : after exploiting the fact that the vorticity is zero: : As fluid dynamics is described by non-canonical dynamics, which possess an infinite amount of Casimir invariants, an alternative formulation of Hamiltonian formulation of fluid dynamics can be introduced through the use of Nambu mechanics 抄文引用元・出典: フリー百科事典『 ウィキペディア(Wikipedia)』 ■ウィキペディアで「Hamiltonian fluid mechanics」の詳細全文を読む スポンサード リンク
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