Transverse instability for periodic waves of KP-I and Schrödinger equations
arXiv:1012.3065
Abstract
We consider the quadratic and cubic KP - I and NLS models in dimensions with periodic boundary conditions. We show that the spatially periodic travelling waves (with period ) in the form $u(t,x,y)=\vp(x-c t)$ are spectrally and linearly unstable, when the perturbations are taken to be with the same period. This strong instability implies other instabilities considered recently - for example with respect to perturbations with periods or bounded perturbations.