FERMI-PASTA-ULAM RECURRENCE AND THE BOUND-STATE SOLITARY-WAVES ON THE FLUID FREE-SURFACE IN A TROUGH

The solution of bound-state of solitary-waves of a NLS type equation governing the modulational evolution of standing gravity wave in a rectangular fluid-trough is given.The time evolution of this solution exhibits the FPU recurrence behaviour,which is in good agreement with the phenomenon observed by Wu et al.in a water trough experiment[Phys.Rev.Lett.52(1984)1421].