ON THE STRUCTURE AND CONTROL OF NEAR-WALL TURBULENCE

A simplified self-sustaining cycle is proposed for the events in the n ear wall region of a turbulent boundary layer. An approximate quantita tive analysis of the resulting model predicts the right dimensions for the sublayer streaks and for other flow structures. The model is chec ked further by applying it to a set of numerical simulations in which the longitudinal and transverse no-slip conditions are applied at diff erent positions with respect to the wall, and to the analysis of flow over riblets. Substantial changes in the flow statistics are obtained, including drag reductions, and the resulting trends are also predicte d correctly by the model.