Measurement of Flow Structures in a Turbulent Boundary Layer
It is conjectured that riblet surfaces effect a drag reduction by organizing the structure of a turbulent flow in the near-wall region of a turbulent boundary layer. However, direct experimental observation is inconclusive, as these are based on single-point measurement probes (like LDV) or qualitative observations with conventional flow visualization. Digital particle image velocimetry (DPIV) is a measurement technique that yields quantitative information of the instantaneous velocity field in a planar cross-section of the flow, and it is especially useful for the investigation of flow structures. We therefore decided to use this technique to make a quantitative investigation of the flow structures in a boundary layer over smooth and riblet surfaces.
KeywordsParticle Image Velocimetry Turbulent Boundary Layer Drag Reduction Streamwise Velocity Measurement Plane
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