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Scaling of velocity fluctuations in statistically unstable boundary-layer flows

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Scaling of velocity fluctuations in statistically unstable boundary-layer flows. / I. A. Yang, Xiang; Pirozzoli, Sergio; Abkar, Mahdi.

I: Journal of Fluid Mechanics, Bind 886, A3, 10.03.2020.

Publikation: Bidrag til tidsskrift/Konferencebidrag i tidsskrift /Bidrag til avisTidsskriftartikelForskningpeer review

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I. A. Yang, Xiang ; Pirozzoli, Sergio ; Abkar, Mahdi. / Scaling of velocity fluctuations in statistically unstable boundary-layer flows. I: Journal of Fluid Mechanics. 2020 ; Bind 886.

Bibtex

@article{7c51b62bd78f47389e95cfd0290382e5,
title = "Scaling of velocity fluctuations in statistically unstable boundary-layer flows",
abstract = "Much of our theoretical understanding of statistically stable and unstable flows is from the classical Monin-Obukhov similarity theory: The theory predicts the scaling of the mean flow well, but its prediction of the turbulent fluctuation is far from satisfactory. This study builds on Monin-Obukhov similarity theory and Townsend's attached-eddy hypothesis. We present a model that connects the mean flow and the streamwise velocity fluctuations in both neutral and unstable boundary-layer flows at both moderate and high Reynolds numbers. The model predictions are compared to direct numerical simulations of weakly unstable boundary layers at moderate Reynolds numbers, and large-eddy simulations of unstable boundary-layer flows at high Reynolds numbers. The flow is shear dominated. The range of stability parameter considered in this work is <![CDATA[$L/\unicode[STIX]{x1D6FF}, where is the Monin-Obukhov length, and is the boundary-layer height. Reasonably good prediction of velocity fluctuations based on knowledge of the mean velocity profile is obtained.",
keywords = "turbulent boundary layers",
author = "{I. A. Yang}, Xiang and Sergio Pirozzoli and Mahdi Abkar",
year = "2020",
month = mar,
day = "10",
doi = "10.1017/jfm.2019.1034",
language = "English",
volume = "886",
journal = "Journal of Fluid Mechanics",
issn = "0022-1120",
publisher = "Cambridge University Press",

}

RIS

TY - JOUR

T1 - Scaling of velocity fluctuations in statistically unstable boundary-layer flows

AU - I. A. Yang, Xiang

AU - Pirozzoli, Sergio

AU - Abkar, Mahdi

PY - 2020/3/10

Y1 - 2020/3/10

N2 - Much of our theoretical understanding of statistically stable and unstable flows is from the classical Monin-Obukhov similarity theory: The theory predicts the scaling of the mean flow well, but its prediction of the turbulent fluctuation is far from satisfactory. This study builds on Monin-Obukhov similarity theory and Townsend's attached-eddy hypothesis. We present a model that connects the mean flow and the streamwise velocity fluctuations in both neutral and unstable boundary-layer flows at both moderate and high Reynolds numbers. The model predictions are compared to direct numerical simulations of weakly unstable boundary layers at moderate Reynolds numbers, and large-eddy simulations of unstable boundary-layer flows at high Reynolds numbers. The flow is shear dominated. The range of stability parameter considered in this work is <![CDATA[$L/\unicode[STIX]{x1D6FF}, where is the Monin-Obukhov length, and is the boundary-layer height. Reasonably good prediction of velocity fluctuations based on knowledge of the mean velocity profile is obtained.

AB - Much of our theoretical understanding of statistically stable and unstable flows is from the classical Monin-Obukhov similarity theory: The theory predicts the scaling of the mean flow well, but its prediction of the turbulent fluctuation is far from satisfactory. This study builds on Monin-Obukhov similarity theory and Townsend's attached-eddy hypothesis. We present a model that connects the mean flow and the streamwise velocity fluctuations in both neutral and unstable boundary-layer flows at both moderate and high Reynolds numbers. The model predictions are compared to direct numerical simulations of weakly unstable boundary layers at moderate Reynolds numbers, and large-eddy simulations of unstable boundary-layer flows at high Reynolds numbers. The flow is shear dominated. The range of stability parameter considered in this work is <![CDATA[$L/\unicode[STIX]{x1D6FF}, where is the Monin-Obukhov length, and is the boundary-layer height. Reasonably good prediction of velocity fluctuations based on knowledge of the mean velocity profile is obtained.

KW - turbulent boundary layers

U2 - 10.1017/jfm.2019.1034

DO - 10.1017/jfm.2019.1034

M3 - Journal article

VL - 886

JO - Journal of Fluid Mechanics

JF - Journal of Fluid Mechanics

SN - 0022-1120

M1 - A3

ER -