Book contents
- Flow Control Techniques and Applications
- Cambridge Aerospace Series
- Flow Control Techniques and Applications
- Copyright page
- Contents
- Preface
- 1 Introduction
- 2 Gurney Flap
- 3 Vortex Generator
- 4 Roughness
- 5 Polymer
- 6 Biological Techniques
- 7 Jet
- 8 Synthetic Jet
- 9 Plasma Actuator
- 10 Lorentz Force
- 11 Closed-Loop Control
- Index
- References
5 - Polymer
Published online by Cambridge University Press: 14 December 2018
Book contents
- Flow Control Techniques and Applications
- Cambridge Aerospace Series
- Flow Control Techniques and Applications
- Copyright page
- Contents
- Preface
- 1 Introduction
- 2 Gurney Flap
- 3 Vortex Generator
- 4 Roughness
- 5 Polymer
- 6 Biological Techniques
- 7 Jet
- 8 Synthetic Jet
- 9 Plasma Actuator
- 10 Lorentz Force
- 11 Closed-Loop Control
- Index
- References
Summary
Polymer is a passive but effective control technique for turbulent drag reduction. The applications of polymer in pipe and channel turbulent flow are introduced. It is indicated that the Reynolds number and polymer concentration are the two important parameters to determine the drag reduction of polymer additives, though there is a maximum drag reduction asymptote. For drag reduction cases, the mean velocity distribution in the viscous sublayer is nearly the same as the baseline Newtonian flow, while that at the logarithmic region is shifted upwards with polymer additives. Statistical study of the coherent structures indicates that the drag reduction is usually accompanied with a modification of the near-wall structures. In particular, the coherent structures become weakened, which is beneficial for drag reduction in turbulent flow.
- Type
- Chapter
- Information
- Flow Control Techniques and Applications , pp. 94 - 107Publisher: Cambridge University PressPrint publication year: 2018
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