Turbulent Boundary Layers Developing over Compliant Surfaces.
Abstract
The flow examined is the two-dimensional turbulent boundary layer over sinusoidal wavy surfaces. The surfaces executed prescribed motion, that of a progressive water-wave. The main conclusions are: The pressure dominates the small skin friction reduction that occurs. At wavespeeds about 7/10 times the freestream speed and higher, the pressure becomes thrust producing for the case of two-dimensional waves. When the waves are swept, the pressure becomes thrust producing as wavespeeds approach the component of the freestream in the direction normal to the wavefront. Therefore the larger the sweep, the smaller the wavespeeds at which the pressure produces thrust. Because of lack of flexible wall experiments, with well defined motion of the sinusoidal wall and high wavespeeds, comparisons were made with water-wave experiments. Reasonable agreement was obtained for measured quantities inside the boundary layer. It was estimated that drag reduction, for the cases considered, is small. Limited comparison with available experiments indicates that the computed trends in the physical quantities are correct. Computations using other approaches and pressure measurements on wavy walls with well defined motion are needed, in order to examine if the turbulence model used in this study is adequate for detailed quantitative predictions. Based on the results of this study, a practical working system with a drag reducing surface with progressive waves does not seem feasible.
Document Details
- Document Type
- Technical Report
- Publication Date
- Jul 01, 1984
- Accession Number
- ADA144268
Entities
People
- S. G. Lekoudis
Organizations
- Georgia Tech