Detection of coherent structures in visual and multiple hot-wire data in boundary layers

A detection scheme developed by Zaric (1975) is verified, using hot-wire and visualization data, to be quantitatively descriptive of all Reynolds-stress-contributing events in U-wire signals; the events are classified as either inrushes toward the wall or ejections from the wall layers. The technique is effective in the Re range of 400 to 10,000. The results indicate that inrushes of high-momentum fluid are a major factor in production of wall turbulence, resulting in the lift-up of ambient fluid. The period between the events is defined with respect to the wall parameters.