Local relaminarization mechanism induced by a dynamic free-slip boundary
- Creators
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Wang, Cong
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Gharib, Morteza
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.
Additional Information
© 2021 American Physical Society. (Received 26 April 2021; accepted 6 July 2021; published 12 August 2021) This work was supported by the Office of Naval Research under Grant No. N00014-15-1-2479. C.W. was supported by the Stanback Fellowship from the Graduate Aeronautical Laboratories of the California Institute of Technology, Caltech.Attached Files
Published - PhysRevFluids.6.084604.pdf
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Additional details
- Eprint ID
- 110616
- Resolver ID
- CaltechAUTHORS:20210830-203807294
- Office of Naval Research (ONR)
- N00014-15-1-2479
- Foster and Coco Stanback Postdoctoral Fellowship
- Created
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2021-08-31Created from EPrint's datestamp field
- Updated
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2023-03-14Created from EPrint's last_modified field
- Caltech groups
- GALCIT