On the occurrence of quasiperiodic motion on three tori

Two systems of three coupled non-linear oscillators are considered, one with linear and one with non-linear coupling. It is shown, with the help of numerical calculations of a number of indicators, that, in both cases, quasiperiodic flow can typically occur on three tori and survive under small changes in the parameters of the two systems. This result could be of consequence in our understanding of non-linear phenomena including turbulence.