Some Visualization Studies on Turbulent Boundary Layers Using Multiwire Hydrogen Bubble Generation,
TECHNISCHE HOGESCHOOL EINDHOVEN (NETHERLANDS)
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This report provides some new results obtained with two visualization methods that assist in describing essentially three dimensional phenomena 1 With two wire certain structure 2 Multiple colour illumination allows recognition of movements in a direction normal to the plane of the photograph from changes in colour. Some countings were made concerning the behaviour of low speed streaks as a function of y and the relation between streaks and some other structures. A new detection criterion for streaks in proposed. The distribution for the spanwise velocity of a streak was determined. It is shown that the detection criterion of Blackwelder and Kaplan essentially samples spanwise passages of streaks. A few results of multiple colour visualization are shown to establish unambiguously the vertical transport associated with streaks.
- Fluid Mechanics