Perturbation analysis for streaks instability in transitional flows

Purpose of the present work is to develop a weakly nonlinear analysis of the streaks breakdown phase in the regeneration process. The model is based on a perturbation expansion of the perturbation field in terms of the amplitude ε of the disturbance. The effect of external noise on streamwise streaks is addressed to follow the destabilization process by accounting at the same time for the temporal evolution of the linear streamwise streaks. Analogies and differences with the classical Floquet theory are illustrated to enlighten limits and advantages of the two formulations.