Journal article
Local relaminarization mechanism induced by a dynamic free-slip boundary
Physical review fluids, Vol.6(8), 084604
08/01/2021
DOI: 10.1103/PhysRevFluids.6.084604
Abstract
Applying a dynamic free-slip boundary in a turbulent boundary layer has been shown recently to shift outward the near-wall transverse vorticity away from the wall and reduces the wall skin friction by more than 40%. Herein we present a local relaminarization mechanism induced by the dynamic free-slip boundary, from the perspective of energy exchange and transportation. The spatial evolution of the energy components associated with the mean motion, turbulent motion, and a shear-free oscillatory motion is presented. An analysis of the average energy exchange process in the near-wall region suggests that the energy of turbulence is transferred to the mean motion, against the canonical downward turbulent energy cascade. A considerable amount of energy is supplied to the shear-free motions, which displaces the highly turbulent and shear motions away from the wall. The relaminarization mechanism is associated with outward-shifted transverse vorticity and the depletion of the shear motions near the wall. As an effective method to manipulate the critical region for wall shear stress generation, the dynamic free-slip boundary produces a much stronger effect than the conventional relaminarization process, which can be employed for efficient drag reduction and boundary layer control.
Details
- Title: Subtitle
- Local relaminarization mechanism induced by a dynamic free-slip boundary
- Creators
- Cong Wang - California Institute of TechnologyMorteza Gharib - California Institute of Technology
- Resource Type
- Journal article
- Publication Details
- Physical review fluids, Vol.6(8), 084604
- DOI
- 10.1103/PhysRevFluids.6.084604
- ISSN
- 2469-990X
- eISSN
- 2469-990X
- Publisher
- Amer Physical Soc
- Number of pages
- 12
- Grant note
- Stanback Fellowship from the Graduate Aeronautical Laboratories of the California Institute of Technology, Caltech N00014-15-1-2479 / Office of Naval Research
- Language
- English
- Date published
- 08/01/2021
- Academic Unit
- Mechanical Engineering
- Record Identifier
- 9984446422102771
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