Since the pioneer work of Townsend (1956), it is now well known that a coherent motion persists in most of shear flows. Following the lines of Townsend's issues, Reynolds & Hussain (1972) provided the first analytical treatment by deriving the "one point" energy budget of the coherent and the random motion respectively. Nevertheless, at least two points must be considered to define a scale and describe the different energy mechanisms at each scale. To this end, transport equations of "two-points" statistics were initially considered by Taylor, Kármán & Howarth, Kolmogorov or Yaglom. These authors claimed that, in the limit of very large Reynolds numbers, there exists a scale beyond which the influence of large coherent structures is no more perceptible. In the meantime, the Reynolds numbers encountered in laboratory experiments are not sufficiently large so that this assumption may be verified. Therefore, the energy contribution of the large scales must be dissociated from the rest of the turbulent spectrum. First, this study aims at extend the previous theories by deriving "two-points" energy budgets which account for the coherent motion. Then, by means of different experiments made at the CORIA and some data arising from a collaboration with the University of Newcastle (Australia), the turbulent wake flow is explored. Statistical theories are thus invoked to describe this flow with an increasing degree of complexity. The interactions between the coherent and the random motion, in terms of transport, of energy contribution and energy transfer are particularly emphasized.
