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Spatiotemporal characteristics of uniform momentum zones: Experiments and modeling

Laskari, Angeliki and de Silva, Charitha M. and Hutchins, Nicholas and McKeon, Beverley J. (2022) Spatiotemporal characteristics of uniform momentum zones: Experiments and modeling. Physical Review Fluids, 7 (10). Art. No. 104603. ISSN 2469-990X. doi:10.1103/physrevfluids.7.104603.

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The probability density function (PDF) of the instantaneous streamwise velocity has consistently been used to extract information on the formation of uniform momentum zones (UMZs) in wall-bounded flows. Its temporal evolution has previously revealed patterns associated with the geometry and amplitude of the underlying velocity fluctuations [Laskari and McKeon, J. Fluid Mech. 913, A6 (2021)]. In this paper, we examine the robustness of these patterns in a variety of data sets including experiments and wall-bounded flow models. Experimental data sets spanning a range of Reynolds numbers, with very long temporal and spatial domains, suggest that the rate of the observed temporal variations scales in inner units. The use of a convection velocity, uniform across heights, to transform space into time has a marginal effect on these features. Similarly, negligible effects are observed between internal and external geometries. Synthetic databases generated following the resolvent framework and the attached eddy model are employed to draw comparisons to the experimental databases. Our findings highlight the distinctive strengths of each: The broadband frequency input of the attached eddy model allows for a better statistical description as opposed to a narrow frequency input in the resolvent data sets; instantaneously, however, representative eddies are seen to lack some structural details leading to the observed temporal behavior, which is better replicated by resolvent modes. Overall, given the considerable variety of the input data tested, the agreement between the data sets highlights the robustness of the spatiotemporal characteristics of the examined UMZs. It also underpins the need for their proper inclusion in UMZ modeling from a statistical as well as an instantaneous viewpoint; the current analysis accentuates important performance indicators for both.

Item Type:Article
Related URLs:
URLURL TypeDescription
Laskari, Angeliki0000-0002-1051-174X
de Silva, Charitha M.0000-0001-9517-4318
Hutchins, Nicholas0000-0003-1599-002X
McKeon, Beverley J.0000-0003-4220-1583
Additional Information:The support of ONR through Grant No. N00014-17-1-3022 (A.L., B.J.M.) is gratefully acknowledged.
Funding AgencyGrant Number
Office of Naval Research (ONR)N00014-17-1-3022
Issue or Number:10
Record Number:CaltechAUTHORS:20221108-874083900.5
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Usage Policy:No commercial reproduction, distribution, display or performance rights in this work are provided.
ID Code:117794
Deposited By: Research Services Depository
Deposited On:18 Nov 2022 21:43
Last Modified:18 Nov 2022 21:43

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