Turbulent drag reduction over curved walls
| Autor: | Paolo Luchini, Jacopo Banchetti, Maurizio Quadrio |
|---|---|
| Rok vydání: | 2020 |
| Předmět: |
Work (thermodynamics)
One half Materials science boundary layer control Turbulence Mechanical Engineering Fluid Dynamics (physics.flu-dyn) FOS: Physical sciences Boundary layer control Physics - Fluid Dynamics Mechanics Condensed Matter Physics 01 natural sciences drag reduction 010305 fluids & plasmas Physics::Fluid Dynamics turbulence control Mechanics of Materials Parasitic drag Drag 0103 physical sciences Compressibility Aerodynamic drag 010306 general physics |
| Zdroj: | Journal of Fluid Mechanics. 896 |
| ISSN: | 1469-7645 0022-1120 |
| DOI: | 10.1017/jfm.2020.338 |
| Popis: | This work studies the effects of skin-friction drag reduction in a turbulent flow over a curved wall, with a view to understanding the relationship between the reduction of friction and changes to the total aerodynamic drag. Direct numerical simulations (DNS) are carried out for an incompressible turbulent flow in a channel where one wall has a small bump; two bump geometries are considered, that produce mildly separated and attached flows. Friction drag reduction is achieved by applying streamwise-travelling waves of spanwise velocity (StTW). The local friction reduction produced by the StTW is found to vary along the curved wall, leading to a global friction reduction that, for the cases studied, is up to 10\% larger than that obtained in the plane-wall case. Moreover, the modified skin friction induces non-negligible changes of pressure drag, which is favorably affected by StTW and globally reduces by up to 10\%. The net power saving, accounting for the power required to create the StTW, is positive and, for the cases studied, is one half larger than the net saving of the planar case. The study suggests that reducing friction at the surface of a body of complex shape induces further effects, a simplistic evaluation of which might lead to underestimating the total drag reduction. |
| Databáze: | OpenAIRE |
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