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A unifying computational fluid dynamics investigation on the river-like to river-reversed secondary circulation in submarine channel bends

A unifying computational fluid dynamics investigation on the river-like to river-reversed secondary circulation in submarine channel bends
A unifying computational fluid dynamics investigation on the river-like to river-reversed secondary circulation in submarine channel bends
A numerical model of saline density currents across a triple-bend sinuous submerged channel enclosed by vertical sidewalls is developed. The unsteady, non-Boussinesq, turbulent form of the Reynolds Averaged Navier-Stokes equations is employed to study the flow structure in a quasi-steady state. Recursive tests are performed with axial slopes of 0.08°, 0.43°, 1.5°, and 2.5°. For each numerical experiment, the downstream and vertical components of the fluid velocity, density, and turbulent kinetic energy are presented at four distinct locations within the channel cross section. It is observed that a crucial change in the flow pattern at the channel bends is observed as the axial slope is increased. At low values of the axial slope a typical river-like pattern is found. At an inclination of 1.5°a transition starts to occur. When the numerical test is repeated with an axial slope of 2.5°, a clearly visible river-reversed secondary circulation is achieved. The change in the cross-sectional flow pattern appears to be associated with the spatial displacement of the core of the maximum downstream fluid velocity. Therefore, the axial slope in this series of experiments is linked to the velocity structure of the currents, with the height of the velocity maximum decreasing as a function of increasing slope. As such, the axial slope should be regarded also as a surrogate for flows with enhanced density or sediment stratification and higher Froude numbers. The work unifies the apparently paradoxical experimental and numerical results on secondary circulation in submarine channels.
0148-0227
1-19
Giorgio-Serchi, F.
8571dc14-19c1-4ed1-8080-d380736a6ffa
Peakall, J.
2351dbf6-2c4f-4250-bacf-fe1b69870f26
Ingham, D.B.
b0036882-6a53-46da-9da9-f1461855087e
Burns, A.D.
001286f9-5a18-4802-bfa7-c675851e759a
Giorgio-Serchi, F.
8571dc14-19c1-4ed1-8080-d380736a6ffa
Peakall, J.
2351dbf6-2c4f-4250-bacf-fe1b69870f26
Ingham, D.B.
b0036882-6a53-46da-9da9-f1461855087e
Burns, A.D.
001286f9-5a18-4802-bfa7-c675851e759a

Giorgio-Serchi, F., Peakall, J., Ingham, D.B. and Burns, A.D. (2011) A unifying computational fluid dynamics investigation on the river-like to river-reversed secondary circulation in submarine channel bends. Journal of Geophysical Research, 116 (C6), 1-19. (doi:10.1029/2010JC006361).

Record type: Article

Abstract

A numerical model of saline density currents across a triple-bend sinuous submerged channel enclosed by vertical sidewalls is developed. The unsteady, non-Boussinesq, turbulent form of the Reynolds Averaged Navier-Stokes equations is employed to study the flow structure in a quasi-steady state. Recursive tests are performed with axial slopes of 0.08°, 0.43°, 1.5°, and 2.5°. For each numerical experiment, the downstream and vertical components of the fluid velocity, density, and turbulent kinetic energy are presented at four distinct locations within the channel cross section. It is observed that a crucial change in the flow pattern at the channel bends is observed as the axial slope is increased. At low values of the axial slope a typical river-like pattern is found. At an inclination of 1.5°a transition starts to occur. When the numerical test is repeated with an axial slope of 2.5°, a clearly visible river-reversed secondary circulation is achieved. The change in the cross-sectional flow pattern appears to be associated with the spatial displacement of the core of the maximum downstream fluid velocity. Therefore, the axial slope in this series of experiments is linked to the velocity structure of the currents, with the height of the velocity maximum decreasing as a function of increasing slope. As such, the axial slope should be regarded also as a surrogate for flows with enhanced density or sediment stratification and higher Froude numbers. The work unifies the apparently paradoxical experimental and numerical results on secondary circulation in submarine channels.

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Serchi_et_al-2011-Journal_of_Geophysical_Research-_Solid_Earth_(1978-2012).pdf - Version of Record
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Accepted/In Press date: 21 March 2011
Published date: 18 June 2011
Organisations: Fluid Structure Interactions Group

Identifiers

Local EPrints ID: 395550
URI: http://eprints.soton.ac.uk/id/eprint/395550
ISSN: 0148-0227
PURE UUID: 7b879e7d-0ba9-4a77-99c4-824a704fd0b2
ORCID for F. Giorgio-Serchi: ORCID iD orcid.org/0000-0002-5090-9007

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Date deposited: 14 Jul 2016 15:08
Last modified: 08 Jan 2022 18:33

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Contributors

Author: F. Giorgio-Serchi ORCID iD
Author: J. Peakall
Author: D.B. Ingham
Author: A.D. Burns

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