Niveau: Supérieur, Doctorat, Bac+8
Stability of small periodic waves for the nonlinear Schrodinger equation Thierry Gallay Institut Fourier Universite de Grenoble I B.P. 74 38402 Saint-Martin-d'Heres, France Mariana Ha˘ra˘gus¸ Departement de Mathematiques Universite de Franche-Comte 16 route de Gray 25030 Besanc¸on, France Abstract The nonlinear Schrodinger equation possesses three distinct six-parameter families of complex- valued quasi-periodic travelling waves, one in the defocusing case and two in the focusing case. All these solutions have the property that their modulus is a periodic function of x?ct for some c ? R. In this paper we investigate the stability of the small amplitude travelling waves, both in the defocusing and the focusing case. Our first result shows that these waves are orbitally stable within the class of solutions which have the same period and the same Floquet exponent as the original wave. Next, we consider general bounded perturbations and focus on spectral stability. We show that the small amplitude travelling waves are stable in the defocusing case, but unstable in the focusing case. The instability is of side-band type, and therefore cannot be detected in the periodic set-up used for the analysis of orbital stability. Running head: Periodic waves in the NLS equation Corresponding author: Mariana Ha˘ra˘gus¸, Keywords: nonlinear Schrodinger equation, periodic waves, orbital stability, spectral stability
- wave
- spectral stability
- nonlinear stability
- periodic solution
- waves reduces
- periodic waves
- has also
- nls equation
- cubic nonlinear