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1.
The multisymplectic geometry for the seismic wave equation is presented in this paper. The local energy conservation law, the local momentum evolution equations, and the multisymplectic form are derived directly from the variational principle. Based on the covariant Legendre transform, the multisymplectic Hamiltonian formulation is developed. Multisymplectic discretization and numerical experiments are also explored.  相似文献   

2.
We establish the existence of a conservative weak solution to the Cauchy problem for the nonlinear variational wave equation u tt c(u)(c(u)u x ) x =0, for initial data of finite energy. Here c(·) is any smooth function with uniformly positive bounded values.  相似文献   

3.
4.
A variational formulation for the multisymplectic Hamiltonian systems is presented in this Letter. Using this variational formulation, we obtain multisymplectic integrators from a variational perspective. Numerical experiments are also reported.Mathematical Subject Classifications (2000). 70G50, 58Z05.  相似文献   

5.
In this paper, we prove the existence of infinitely many solutions of a stationary nonlinear Dirac equation on the Schwarzschild metric, outside a massive ball. These solutions are the critical points of a strongly indefinite functional. Thanks to a concavity property, we are able to construct a reduced functional, which is no longer strongly indefinite. We find critical points of this new functional using the Symmetric Mountain Pass Lemma. Note that, as A. Bachelot-Motet conjectured, these solutions vanish as the radius of the massive ball tends to the horizon radius of the metric. Received: 2 August 1999 / Accepted: 14 February 2000  相似文献   

6.
We investigate the multisymplectic Euler box scheme for the Korteweg-de Vries (KdV) equation. A new completely explicit six-point scheme is derived. Numerical experiments of the new scheme with comparisons to the Zabusky-Kruskal scheme, the multisymplectic 12-point scheme, the narrow box scheme and the spectral method are made to show nice numerical stability and ability to preserve the integral invariant for long-time integration.  相似文献   

7.
SRLW方程的多辛Fourier谱格式及其守恒律   总被引:1,自引:0,他引:1  
通过引进正则动量,将对称正则长波方程(简称SRLW方程)转化成多辛形式的方程组,它具有多辛守恒律;介绍了空间方向满足周期边界条件的函数的Fourier谱方法;对SRLW方程的多辛方程组在空间方向利用Fourer谱方法,时间方向上应用Euler中点格式离散,得到其多辛Fourier拟谱格式;证明此格式的一些离散守恒律.用此格式模拟了SRLW方程的单个孤立波,还模拟了多个孤立波的追赶、碰撞和分离过程.  相似文献   

8.
In this paper we prove a new variational principle for the Navier-Stokes equation which asserts that its solutions are critical points of a stochastic control problem in the group of area-preserving diffeomorphisms. This principle is a natural extension of the results by Arnold, Ebin, and Marsden concerning the Euler equation.Supported in part by FCT/POCTI/FEDER  相似文献   

9.
孔令华  曹莹  王兰  万隆 《计算物理》2011,28(5):730-736
对一类带三次非线性项的四阶Schr(o)dinger方程提出分裂多辛格式.其基本思想是将多辛算法和分裂方法相结合,既具有多辛格式固有的保多辛几何结构的特性,又发挥了分裂方法在计算上灵活高效的特点.数值实验结果表明,分裂多辛格式比其它传统的多辛格式更节约计算时间和计算机的内存,从而更加优越.  相似文献   

10.
The multisymplectic geometry for the Zakharov–Kuznetsov equation is presented in this Letter. The multisymplectic form and the local energy and momentum conservation laws are derived directly from the variational principle. Based on the multisymplectic Hamiltonian formulation, we derive a 36-point multisymplectic integrator.  相似文献   

11.
给出了高阶非线性薛定谔方程的一个新型孤波解, 该解描述了满足一定参数条件时光纤中超短光脉冲的传输, 解的表达式可以表示为亮孤子和暗孤子和的形式. 同时利用分步傅里叶方法在一定微扰条件下对脉冲传输进行了数值模拟.  相似文献   

12.
Multisymplectic structures for one-way wave equations are presented in this letter. Based on the multisymplectic formulation, we obtain the corresponding multisymplectic discretizations. The structure-preserving property of a finite difference scheme for the first-order one-way wave equation is proved. Implications and applications of this result are explored.   相似文献   

13.
In this paper we discuss symmetries of a nonlinear wave equation that arises as a consequence of some Riemannian metrics of signature −2. The objective of this study is to show how geometry can be responsible in giving rise to a nonlinear inhomogeneous wave equation rather than assuming nonlinearities in the wave equation from physical considerations. We find Lie point symmetries of the corresponding wave equations and give their solutions in two cases. Some interesting physical conclusions relating to conservation laws such as energy, linear and angular momenta are also determined.  相似文献   

14.
For ion-acoustic waves in a plasma with non-isothermal electrons,the MKP equation is its governing equation.The instability of a soliton solution of MKP equation to two-dimensional long-wavelength perturbations is investigated up to the third order.It indicates that the one-soliton solution of MKP equation is unstable if v = -1wheras it is stable if v = 1 until the third order approximation has been considered.  相似文献   

15.
Solving Nonlinear Wave Equations by Elliptic Equation   总被引:5,自引:0,他引:5  
The elliptic equation is taken as a transformation and applied to solve nonlinear wave equations. It is shown that this method is more powerful to give more kinds of solutions, such as rational solutions, solitary wave solutions,periodic wave solutions and so on, so it can be taken as a generalized method.  相似文献   

16.
Abstract

Group classification of the nonlinear wave equation is carried out and the conditional invariance of the wave equation with the nonlinearity F (u) = u is found.  相似文献   

17.
We present symplectic and multisymplectic formulations of the Klein-Gordon equation in this paper. Based on these two formulations, we investigate the corresponding symplectic and multisymplectic Fourier pseudospectral discretizations. The relationship between these two kinds of Fourier pseudospectral discretizations is discussed. Time discretizations are also presented.  相似文献   

18.
Multisymplectic geometry for the Schrodinger equation in quantum mechanics is presented. This formalism of multisymplectic geometry provides a concise and complete introduction to the Schrodinger equation. The Schrodinger equation, its associated energy and momentum evolution equations, and the multisymplectic form are derived directly from the variational principle. Some applications are also explored.  相似文献   

19.
首先把一维Gross-Pitaevskli方程改写成多辛Hamiltonian系统的形式,把形式通过分裂变成2个子哈密尔顿系统.然后,对这些子系统用辛或者多辛算法进行离散.通过对子系统数值算法的不同组合方式,得到不同精度的具有多辛算法特征数值格式.这些格式不仅具有多辛格式、分裂步方法和高阶紧致格式的特征,而且是质量守恒的.数值实验验证了新格式的数值行为.  相似文献   

20.
We study resonances (scattering poles) associated to the elasticity operator in the exterior of an arbitrary obstacle with Neumann or Dirichlet boundary conditions. We prove that there exists an exponentially small neighborhood of the real axis free of resonances. Consequently we prove that for regular data, the energy for the elastic wave equation decays at least as fast as the inverse of the logarithm of time. According to Stefanov–Vodev ([SV1, SV2]), our results are optimal in the case of a Neumann boundary condition, even when the obstacle is a ball of ℝ3. The main difference between our case and the case of the scalar Laplacian (see Burq [Bu]) is the phenomenon of Rayleigh surface waves, which are connected to the failure of the Lopatinskii condition. Received: 22 February 2000 / Accepted: 28 June 2000  相似文献   

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