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arXiv 1001.2134nlin.SI
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n+1维无色散Kadomtsev-Petviashvili方程:精确解、小初始数据的柯西问题和波破碎

On the dispersionless Kadomtsev-Petviashvili equation in n+1 dimensions: exact solutions, the Cauchy problem for small initial data and wave breaking

S. V. Manakov, P. M. Santini

摘要:

我们研究了无色散Kadomtsev-Petviashvili(dKP)方程的(n+1)维推广,dKP方程是一个描述弱非线性准一维波在n+1维中传播的普适方程,它在声学、等离子体物理和流体力学等多种物理背景下产生.当n=2时,该方程是可积的,并且最近已被证明是描述局部化初始数据的二维波破碎的原型模型方程。本文构造了n+1维模型的精确解,该模型包含一个任意的单变量函数,对应于它的抛物不变性,描述波,在抛物面波前上为常数,在其所有点上同时破裂.然后,我们用这样的解建立了Cauchy问题解的一致逼近,对于小的和局部化的初始数据,显示了根据(n+1)维dKP方程演化的这种小的和局部化的初始数据在长时间范围内破裂,当且仅当n= 1,2,3;即,在物理空间中。这样的波破碎发生,一般来说,在一个点的抛物面波阵面,它的分析方面给出了明确的小的初始数据。

英文摘要:

We study the (n+1)-dimensional generalization of the dispersionless Kadomtsev-Petviashvili (dKP) equation, a universal equation describing the propagation of weakly nonlinear, quasi one dimensional waves in n+1 dimensions, and arising in several physical contexts, like acoustics, plasma physics and hydrodynamics. For n=2, this equation is integrable, and it has been recently shown to be a prototype model equation in the description of the two dimensional wave breaking of localized initial data. We construct an exact solution of the n+1 dimensional model containing an arbitrary function of one variable, corresponding to its parabolic invariance, describing waves, constant on their paraboloidal wave front, breaking simultaneously in all points of it. Then we use such solution to build a uniform approximation of the solution of the Cauchy problem, for small and localized initial data, showing that such a small and localized initial data evolving according to the (n+1)-dimensional dKP equation break, in the long time regime, if and only if n=1,2,3; i.e., in physical space. Such a wave breaking takes place, generically, in a point of the paraboloidal wave front, and the analytic aspects of it are given explicitly in terms of the small initial data.

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