Accession Number : ADP004176

Title :   Natural Unsteadiness of a Separation Bubble behind a Backward-Facing Step,

Corporate Author : STANFORD UNIV CA DEPT OF MECHANICAL ENGINEERING

Personal Author(s) : Eaton,J. K. ; Alving,A. E.

Report Date : 1984

Pagination or Media Count : 3

Abstract : Low-frequency unsteadiness of a reattaching shear layer was studied in subsonic flow behind a backward-facing step. Power spectra of streamwise velocity fluctuations were measured using a hotwire probe. Spectra measured near the centerline of the separated shear layer showed that a substantial fraction of the measured turbulence intensity occurs at frequencies significantly lower than the large-eddy passing frequency. The strong low-large-eddy passing frequency. The strong low-frequency contribution is not present in the upstream boundary layer or in the reattached shear layer. It was concluded that the low-frequency energy is caused by a non-periodic vertical motion of the separated shear layer. (Author)

Descriptors :   *Subsonic flow, Flow separation, Bubbles, Unsteady flow, Shear properties, Boundary layer flow, Attachment, Low frequency, Velocity, Variations, Power spectra, Turbulence, Measurement, Hot wire anemometers

Distribution Statement : APPROVED FOR PUBLIC RELEASE