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Local relaminarization mechanism induced by a dynamic free-slip boundary

Wang, Cong and Gharib, Morteza (2021) Local relaminarization mechanism induced by a dynamic free-slip boundary. Physical Review Fluids, 6 (8). Art. No. 084604. ISSN 2469-990X. doi:10.1103/PhysRevFluids.6.084604. https://resolver.caltech.edu/CaltechAUTHORS:20210830-203807294

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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.


Item Type:Article
Related URLs:
URLURL TypeDescription
https://doi.org/10.1103/physrevfluids.6.084604DOIArticle
ORCID:
AuthorORCID
Wang, Cong0000-0002-8271-5637
Gharib, Morteza0000-0003-0754-4193
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.
Group:GALCIT
Funders:
Funding AgencyGrant Number
Office of Naval Research (ONR)N00014-15-1-2479
Foster and Coco Stanback Postdoctoral FellowshipUNSPECIFIED
Issue or Number:8
DOI:10.1103/PhysRevFluids.6.084604
Record Number:CaltechAUTHORS:20210830-203807294
Persistent URL:https://resolver.caltech.edu/CaltechAUTHORS:20210830-203807294
Usage Policy:No commercial reproduction, distribution, display or performance rights in this work are provided.
ID Code:110616
Collection:CaltechAUTHORS
Deposited By: George Porter
Deposited On:31 Aug 2021 14:15
Last Modified:31 Aug 2021 14:15

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