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arXiv 2103.07490nlin.PS
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长程相互作用晶格中孤立波行波的不稳定动力学

Unstable dynamics of solitary traveling waves in a lattice with long-range interactions

H. Duran, H. Xu, P. G. Kevrekidis, A. Vainchtein

摘要:

在这项工作中,我们重新审视的存在性,稳定性和动力学的不稳定孤立波的背景下,晶格动力系统。我们考虑一个$α$ -Fermi-Pasta-Ulam型的非线性晶格,它具有一个附加的特征,即所有对所有的谐波长程相互作用,其强度随距离呈指数衰减。非线性最近邻项和长程线性项之间的竞争产生两个参数区域,其中行波的能量$H$对它们的速度$c$的依赖性分别是非单调和多值的。我们检查这两种情况下,并确定确切的(规定的数值公差)行波。为了研究所得到的解决方案的稳定性,我们计算他们的Floquet乘子,思想的行波问题作为一个周期的模移位。我们表明,在一般情况下,当$H$和$c$之间的关系不是单值的,充分的,但不是必要的稳定性变化的标准是$H'(s)=0$,其中$s$是沿能量-速度曲线的参数。沿着相应的特征向量扰动不稳定的解决方案,我们确定了两种不同的情况下,他们的过渡到稳定的分支的动态。在第一种情况下,扰动波在驱逐色散波后减慢。第二种情况涉及的扰动波的速度增加伴随着形成一个较慢的小振幅孤立波。

英文摘要:

In this work we revisit the existence, stability and dynamics of unstable traveling solitary waves in the context of lattice dynamical systems. We consider a nonlinear lattice of an $α$-Fermi-Pasta-Ulam type with the additional feature of all-to-all harmonic long-range interactions whose strength decays exponentially with distance. The competition between the nonlinear nearest-neighbor terms and the longer-range linear ones yields two parameter regimes where the dependence of the energy $H$ of the traveling waves on their velocity $c$ is non-monotonic and multivalued, respectively. We examine both cases, and identify the exact (up to a prescribed numerical tolerance) traveling waves. To investigate the stability of the obtained solutions, we compute their Floquet multipliers, thinking of the traveling wave problem as a periodic one modulo shifts. We show that in the general case when the relationship between $H$ and $c$ is not single-valued, the sufficient but not necessary criterion for stability change is $H'(s)=0$, where $s$ is the parameter along the energy-velocity curve. Perturbing the unstable solutions along the corresponding eigenvectors, we identify two different scenarios of the dynamics of their transition to stable branches. In the first one, the perturbed wave slows down after expelling a dispersive wave. The second scenario involves an increase in the velocity of the perturbed wave accompanied by the formation of a slower small-amplitude traveling solitary wave.

机构、总结、中文摘要均由AI分析而来,可能存在错误,请以论文正文为准。

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