MECHANISM BY WHICH A TWO-DIMENSIONAL ROUGHNESS ELEMENT INDUCES BOUNDARY-LAYER TRANSITION: ROUGHNESS INDUCED TRANSITION
An experimental investigation of the effect of two-dimensional roughness elements on boundary layer transition is described. Primary emphasis is given to the nature of disturbances within the recovery zone, i.e., that region in the immediate downstream of the roughness where the mean flow has been distorted by the presence of the roughness. Detailed measurements of mean velocity distributions, of disturbance spectra, and intensity, growth, and decay of disturbances at discrete frequencies were made for a range of unit Reynolds number. The measurements demonstrate that the behavior can best be understood by considering wave-type disturbances, and that the basic mechanism by which a two-dimensional roughness element induces earlier transition to turbulent flow is by the destabilizing influence of the flow within the recovery zone. Comparison with the behavior expected from stability theory supports this conclusion.
- Published in Physics of Fluids, V 15 N 7, pp 1173-1188, July 1972.
National Bureau of StandardsCommerce Department
Washington, DC USA 20234
- Klebanoff, P S
- Tidstrom, K D
- Publication Date: 1972
- Pagination: 16 p.
- TRT Terms: Boundary layer; Roughness; Transitional flow; Two dimensional flow
- Old TRIS Terms: Boundary layer stability
- Subject Areas: Design; Marine Transportation;
- Accession Number: 00040885
- Record Type: Publication
- Source Agency: National Technical Information Service
- Report/Paper Numbers: Final Rpt
- Contract Numbers: W-13-147
- Files: TRIS
- Created Date: Feb 14 1973 12:00AM