Flow control for turbulent skin-friction drag reduction is applied to a transonic airfoil improve its aerodynamic performance. The study based on direct numerical simulations (with up 1.8 billion cells) of the compressible flow around supercritical airfoil, at Reynolds and Mach numbers $Re_\infty = 3 \times 10^{5}$ $M_\infty =0.7$ . Control via spanwise forcing over fraction suction side airfoi...

This paper explores the use of sharkskin in improving aerodynamic performance aerofoils. A biomimetic analysis denticles was conducted and were incorporated on surface a 2-Dimensional (2D) NACA0012 aerofoil. The including drag reduction rate, lift enhancement Lift to Drag (L/D) rate for calculated at different locations along chord line aerofoil Angles Attack (AOAs) through Computational Fluid ...

For prawn trawling systems, drag reduction is a high priority as the trawling process is energy intensive. Large benefits have occurred through the use of multiple-net rigs and thin twine in the netting. An additional positive effect of these successful twine-area reduction strategies is the reduced amount of otter board area required to spread the trawl systems, which leads to further drag red...

This paper presents efflux time experiments performed in the absence and presence of aqueous solutions of Drag Reducing Agents (DRAs) when a liquid is emptied from a large open cylindrical storage tank through an exit piping system. The drag reducing agents studied are Dodecyl benzene sulfonate anionic surfactant and a mixed solution of surfactant and sodium chloride counter ion. The variab...

We investigate the phenomenon of drag reduction in a viscoelastic fluid model of dilute polymer solutions. By means of direct numerical simulations of the three-dimensional turbulent Kolmogorov flow we show that drag reduction takes place above a critical Reynolds number Re(c). An explicit expression for the dependence of Re(c) on polymer elasticity and diffusivity is derived. The values of the...

a series of subsonic wind tunnel tests was conducted on an ogive-cylinder-flare configuration at zero angle of attack to study the effects of small helical protuberances on viscous drag reduction behavior. the experiments have been carried out on a smooth model and two wire-wrapped models with different spacing between the helical riblet rings, known as pitch length. in the present experiments,...

In team pursuit, the drag of a group of cyclists riding in a pace line is dependent on several factors, such as anthropometric characteristics (stature) and position of each cyclist as well as the sequence in which they ride. To increase insight in drag reduction mechanisms, the aerodynamic drag of four cyclists riding in a pace line was investigated, using four different cyclists, and for four...