Friction drag reduction achievable by near-wall turbulence manipulation in spatially developing boundary-layer
Various control strategies, such as active feedback control or riblets, end up restraining near-wall turbulence. An analytical study is conducted to estimate the drag-reduction achievable by such control in zero-pressure-gradient turbulent boundary-layers. Based on an idealized control which damps all fluctuations within a near-wall layer, a composite flow profile is established. It leads to explicit models for both the drag-reduction and the boundary-layer development rate. A skin-friction decomposition is applied and gives physical insights on the underlying phenomena. The control is found to alter the spatial development of the boundary-layer, resulting in detrimental impact on the skin-friction. However, the drag-reducing mechanism, attributed to the turbulence weakening, is found predominant and massive drag reductions remain achievable at high Reynolds number, although a minute part of the boundary-layer is manipulated. The model is finally assessed against Large Eddy Simulations of riblet-controlled flow.
Amaury Bannier, Eric Garnier, Pierre Sagaut. Friction drag reduction achievable by near-wall turbulence manipulation in spatially developing boundary-layer. Physics of Fluids, American Institute of Physics, 2016, 28 (035108), 16 p. ⟨10.1063/1.4943625⟩. ⟨hal-01428632⟩
Journal: Physics of Fluids
Date de publication: 17-03-2016