NEGATIVE STREAMWISE SKIN-FRICTION IN NEAR-WALL TURBULENCE
Session: Wall-bounded flows 6
Session starts: Friday 28 August, 10:30
Presentation starts: 11:15
Room: Room B
Christoph Bruecker (Institute of Mechanics and Fluid Dynamics, TU Freiberg, Germany)
The recent discovery of rare backflow events in turbulent boundary layer flows based on the analysis of DNS data has raised again the need of experimental visualizations of wall-shear stress (WSS) fields in such unsteady flows. Of importance is the localization of critical points which are thought to strongly correlate with large-scale events in the log-layer. Up to now there is no experimental prove of these rare events and their topological patterns in the skin-friction field. Their existence in a turbulent boundary-layer flow is shown herein by means of imaging with 2D arrays of flexible micropillars attached at the wall.