[PDF] Top 20 Effectiveness of active flow control for turbulent skin friction drag reduction

... the flow field to the opposition control is ...opposition control is no longer ...positive drag reduction and increases for negative ... See full document

... a turbulent boun- dary-layer, ...and skin friction should be studied (this constitutes a biomimetic ...affects skin drag reduction has been studied by many researchers using ... See full document

... both flow configurations plotted in Figure 5 show that only the spanwise wall oscillation (γ = 90˚) has achieved the maximum drag reduction whereas the streamwise oscillation (γ = 0˚) leads to the ... See full document

... Controlling turbulent flow artificially was believed to be extremely difficult several decades ago, until the discovery of turbulent coherent structures and improved understanding of the underlying ... See full document

... a turbulent channel ...canonical turbulent flow over a smooth, impermeable ...a turbulent regime, the fluctuations of the normal-to-the-wall velocity component increase as the wall ... See full document

... a skin friction reduction was observed, a secondary vortical flow was ...studies skin friction reduction had been achieved by manipulating the transverse velocity ... See full document

... flow control. The present DNS results confirm that the effectiveness of drag reduction deteriorates, and the maximum drag reduction achieved by travelling waves decreases ... See full document

... The experiment was conducted in the T2 low speed wind tunnel at the Handley Page laboratory at City, University of London which has a working section of 0.8m × 1.12m × 1.8m. The experimental bound- ary layer was ... See full document

... increased skin friction drag. Consequently, drag reduction studies are an important focus of turbulent ...Both active (intervening in a turbulent flow based ... See full document

... Following these ideas a computational parallelisation was implemented employing Message-Passing protocols aiming to speed-up simultaneous multiple spanwise modes simulations. In particular, this sort of parallel ... See full document

... to close the problem. Using the PIV data, both the total thrust and the spatial distribution can be estimated. To estimate the thrust force, Durscher and Roy (2012) and Kotsonis et al. (2010) assumed the pressure was ... See full document

... derive friction factor directly in one step while iterative calculus can cause problem in simulation of flow in a pipe system in which it may be necessary to evaluate friction factor hundreds or ... See full document

... The grids with number of cells varying from approximately 150000 -200000 were generated for different bluntness ratios and different ogive radius. The grids were made fine in the shock dominated regions in order to ... See full document

... an active flow control device or passive flow control ...Passive control usually utilizes the method of geometry modification and this devices are always operating, regardless of ... See full document

... Techniques such as hot-wire anemometry, particle image velocimetry, floating ele- ment balances, Preston-tube methods and oil-film interferometry have been devel- oped to enable observations and analysis of specific ... See full document

... shark skin and smooth control membrane propulsion under three different kinematic conditions ...shark skin model generated noticeably better swimming performance (a significant increase in SPS speed ... See full document

... for drag reduction uses spatial heating patterns (Hossain & Floryan, 2016) that create a buoyancy field which leads to the formation of a system of separation ...the flow has to be fairly slow as ... See full document

... the skin of fast swimming sharks impede the cross-stream translation of the streamwise vortices ...for drag reduction due to the fact that it actually increases the total wetted surface area which ... See full document

... Papaevangelou, G., Evangelides, C., Tzimopoulos, C. (2010). “A new explicit relation for the friction factor coefficient in the Darcy–Weisbach equation.”, Protection and Restoration of the Environment, University ... See full document

... ... See full document