ENERGY EXCHANGE IN WEAKLY COUPLED FPU CHAINS
Leonid Manevich
We consider two limiting cases in the problem of energy exchange between two weakly Fermi-Pasta-Ulama (FPU) chains. The case of weak coupling demonstrates full absence of competition between the processes if intra-chain excitation and interchain energy transfer because these ones are separated in the time scale. Another limit of “superweak” bond is more complicated since the processes mentioned above proceed in the same time scale. Both limits are studied by asymptotic method. It is shown that the main peculiarities of the processes can be understood due to close analogy with the system of two coupled nonlinear oscillators. The conditions which determine the transition from full energy exchange to confinement of excitation on one of chains are discussed. Main conclusions of analytical study are in a good agreement with computer simulation data.