Emergence of Kelvin-Helmholtz instabilities in shallow mixing layers: An experimental study

S. Proust; C. Berni; V. I. Nikora

doi:10.1201/b22619

Emergence of Kelvin-Helmholtz instabilities in shallow mixing layers: An experimental study

S. Proust, C. Berni, V. I. Nikora

Engineering

INRAE

Research output: Chapter in Book/Report/Conference proceeding › Published conference contribution

Abstract

Free-surface shallow mixing layers behind a splitter plate were studied in a flume of rectangular cross-section consisting of a bed and sidewalls made of glass. The focus is on the effects on the emergence of horizontal Kelvin-Helmholtz-type coherent structures (KHCSs) of vertical flow confinement (i.e., flow depth) and dimensionless velocity shear λ=(U_X2 - U_X1) / (U_X2 + U_X1) where U_X1 and U_X2 are two flow velocities characterizing the low-speed stream and high-speed stream, respectively. Two flow depths were tested, with the λ-value at the flume entrance varying between 0.1 to 0.8, with a threshold value λ = 0.3 needed for the emergence of KHCSs in compound open-channel flows being inside this range. This paper reports new data that provide a better insight in the interplay between the constraining effect of flow depth, damping effect of three-dimensional bed-induced turbulence, and triggering effect of dimensionless shear on the formation of KHCSs.

Original language	English
Title of host publication	River Flow 2020
Subtitle of host publication	Proceedings of the 10th Conference on Fluvial Hydraulics (Delft, Netherlands, 7-10 July 2020)
Editors	Wim Uijttewaal, Mario J. Franca, Daniel Valero, Victor Chavarrias, Claudia Ylla Arbos, Ralph Schielen, Ralph Schielen, Alessandra Crosato
Publisher	CRC Press/Balkema
Pages	76-83
Number of pages	8
ISBN (Electronic)	9780367627737
DOIs	https://doi.org/10.1201/b22619
Publication status	Published - 10 Jul 2020
Event	10th Conference on Fluvial Hydraulics, River Flow 2020 - Virtual, Online, Netherlands Duration: 7 Jul 2020 → 10 Jul 2020

Conference

Conference	10th Conference on Fluvial Hydraulics, River Flow 2020
Country/Territory	Netherlands
City	Virtual, Online
Period	7/07/20 → 10/07/20

Keywords

Coherent structures
Shallow shear flows
Shear layer turbulence

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10.1201/b22619Licence: Unspecified

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Proust, S., Berni, C., & Nikora, V. I. (2020). Emergence of Kelvin-Helmholtz instabilities in shallow mixing layers: An experimental study. In W. Uijttewaal, M. J. Franca, D. Valero, V. Chavarrias, C. Y. Arbos, R. Schielen, R. Schielen, & A. Crosato (Eds.), River Flow 2020: Proceedings of the 10th Conference on Fluvial Hydraulics (Delft, Netherlands, 7-10 July 2020) (pp. 76-83). CRC Press/Balkema. https://doi.org/10.1201/b22619

Emergence of Kelvin-Helmholtz instabilities in shallow mixing layers: An experimental study. / Proust, S.; Berni, C.; Nikora, V. I.
River Flow 2020: Proceedings of the 10th Conference on Fluvial Hydraulics (Delft, Netherlands, 7-10 July 2020). ed. / Wim Uijttewaal; Mario J. Franca; Daniel Valero; Victor Chavarrias; Claudia Ylla Arbos; Ralph Schielen; Ralph Schielen; Alessandra Crosato. CRC Press/Balkema, 2020. p. 76-83.

Research output: Chapter in Book/Report/Conference proceeding › Published conference contribution

Proust, S, Berni, C & Nikora, VI 2020, Emergence of Kelvin-Helmholtz instabilities in shallow mixing layers: An experimental study. in W Uijttewaal, MJ Franca, D Valero, V Chavarrias, CY Arbos, R Schielen, R Schielen & A Crosato (eds), River Flow 2020: Proceedings of the 10th Conference on Fluvial Hydraulics (Delft, Netherlands, 7-10 July 2020). CRC Press/Balkema, pp. 76-83, 10th Conference on Fluvial Hydraulics, River Flow 2020, Virtual, Online, Netherlands, 7/07/20. https://doi.org/10.1201/b22619

Proust S, Berni C, Nikora VI. Emergence of Kelvin-Helmholtz instabilities in shallow mixing layers: An experimental study. In Uijttewaal W, Franca MJ, Valero D, Chavarrias V, Arbos CY, Schielen R, Schielen R, Crosato A, editors, River Flow 2020: Proceedings of the 10th Conference on Fluvial Hydraulics (Delft, Netherlands, 7-10 July 2020). CRC Press/Balkema. 2020. p. 76-83 doi: 10.1201/b22619

Proust, S. ; Berni, C. ; Nikora, V. I. / Emergence of Kelvin-Helmholtz instabilities in shallow mixing layers : An experimental study. River Flow 2020: Proceedings of the 10th Conference on Fluvial Hydraulics (Delft, Netherlands, 7-10 July 2020). editor / Wim Uijttewaal ; Mario J. Franca ; Daniel Valero ; Victor Chavarrias ; Claudia Ylla Arbos ; Ralph Schielen ; Ralph Schielen ; Alessandra Crosato. CRC Press/Balkema, 2020. pp. 76-83

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N2 - Free-surface shallow mixing layers behind a splitter plate were studied in a flume of rectangular cross-section consisting of a bed and sidewalls made of glass. The focus is on the effects on the emergence of horizontal Kelvin-Helmholtz-type coherent structures (KHCSs) of vertical flow confinement (i.e., flow depth) and dimensionless velocity shear λ=(UX2 - UX1) / (UX2 + UX1) where UX1 and UX2 are two flow velocities characterizing the low-speed stream and high-speed stream, respectively. Two flow depths were tested, with the λ-value at the flume entrance varying between 0.1 to 0.8, with a threshold value λ = 0.3 needed for the emergence of KHCSs in compound open-channel flows being inside this range. This paper reports new data that provide a better insight in the interplay between the constraining effect of flow depth, damping effect of three-dimensional bed-induced turbulence, and triggering effect of dimensionless shear on the formation of KHCSs.

AB - Free-surface shallow mixing layers behind a splitter plate were studied in a flume of rectangular cross-section consisting of a bed and sidewalls made of glass. The focus is on the effects on the emergence of horizontal Kelvin-Helmholtz-type coherent structures (KHCSs) of vertical flow confinement (i.e., flow depth) and dimensionless velocity shear λ=(UX2 - UX1) / (UX2 + UX1) where UX1 and UX2 are two flow velocities characterizing the low-speed stream and high-speed stream, respectively. Two flow depths were tested, with the λ-value at the flume entrance varying between 0.1 to 0.8, with a threshold value λ = 0.3 needed for the emergence of KHCSs in compound open-channel flows being inside this range. This paper reports new data that provide a better insight in the interplay between the constraining effect of flow depth, damping effect of three-dimensional bed-induced turbulence, and triggering effect of dimensionless shear on the formation of KHCSs.

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KW - Shear layer turbulence

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PB - CRC Press/Balkema

Y2 - 7 July 2020 through 10 July 2020

ER -

Emergence of Kelvin-Helmholtz instabilities in shallow mixing layers: An experimental study

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