Experimental Study of the Fluid Mechanics of Unsteady Turbulent Boundary Layers.
Final rept. 3 Jul 83-6 Jan 86,
STANFORD UNIV CA THERMOSCIENCES DIV
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An experimental study of the effects of forced, free-stream unsteadiness on turbulent boundary layers was undertaken in an effort to characterize the nature of such flows and to provide guidance for turbulence modelers. A turbulent boundary layer, which had developed under steady, constant-pressure conditions, was locally subjected to a range of frequencies of sinusoidal free-stream unsteadiness. The response of the boundary layer to these free-stream effects was studied through simultaneous measurements of the u and v components of the velocity field, using a two-color laser-doppler anemometer. To focus on the distinct behaviors of the deterministic and time-averaged fields of flow, the equations of fluid motion were reformulated according to a triple decomposition of velocity and pressure into i a time-averaged measure, ii a deterministic or organized, unsteady measure, and iii a turbulent measure.
- Fluid Mechanics