Near-Wall Flow Statistics in High- Reτ Drag-Reduced Turbulent Boundary Layers

Abstract

Manipulating the organized flow in the near-wall region of a turbulent boundary layer is a direct path to achieving skin-friction drag reduction. However, near-wall flow measurements in high Reynolds number (Reτ) wall flows can be challenging, due to this region’s small physical size and measurement resolution issues. The present study demonstrates the capability of hot-wire (HW) and stereoscopic particle image velocimetry (PIV) techniques of accurately estimating the trends of near-wall flow statistics in high-Reτ drag-reduced turbulent boundary layers. The drag reduction strategy considered involves imposition of streamwise travelling waves of spanwise wall oscillations, well known for att..