Delay of laminar–turbulent transition by counter-rotating cylindrical roughness elements in a laminar flat plate boundary layer.
- Resource Type
- Article
- Authors
- Römer, Tristan M.; Schulz, Kai A.; Wu, Yongxiang; Wenzel, Christoph; Rist, Ulrich
- Source
- Experiments in Fluids. Feb2023, Vol. 64 Issue 2, p1-8. 8p.
- Subject
- *BOUNDARY layer (Aerodynamics)
*TURBULENT boundary layer
- Language
- ISSN
- 0723-4864
Delaying laminar–turbulent transition in boundary layers is of great interest since the skin-friction coefficient can be reduced by up to one order of magnitude. In this experimental research, it is shown that counter-rotating cylindrical roughness elements are able to delay transition under realistic flow conditions. Evidence is given by the intermittency, evaluated from hot-film measurements in a laminar water channel. An increase in rotation speed results in a delay of transition of up to 6.5 % in the center of the plate. This trend can be explained by the streaks amplified by the rotating cylinders, resulting in a damping of the fluctuation amplitude in the boundary layer. The advantage of this method is that the transition delay can be actively controlled with conventional cylindrical roughness elements. [ABSTRACT FROM AUTHOR]