Physics of temporal forcing in wakes

In this paper, we review some recent results concerning the physics of forcing in open flows. First, we recall some properties of global modes in wakes, showing their shapes and their dependence on the Reynolds number and underline the importance of the mean flow correction induced by the fluctuations. Second, we show how a local temporal forcing can affect these properties, always through the modification of the mean flow, until the wake reaches a critical transition even far from the threshold. At last, we address some conjectures about an extended model suitable for describing the dynamics of forced wakes.