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Flow dynamics and mixing processes in hydraulic jump arrays: Implications for channel-lobe transition zones

Flow dynamics and mixing processes in hydraulic jump arrays: Implications for channel-lobe transition zones
Flow dynamics and mixing processes in hydraulic jump arrays: Implications for channel-lobe transition zones
A detailed field investigation of a saline gravity current in the southwest Black Sea has enabled the first complete analysis of three-dimensional flow structure and dynamics of a series of linked hydraulic jumps in stratified, density-driven, flows. These field observations were collected using an acoustic Doppler current profiler mounted on an autonomous underwater vehicle, and reveal that internal mixing processes in hydraulic jumps, including flow expansion and recirculation, provide a previously unrecognised mechanism for grain-size sorting and segregation in stratified density-driven flows. Field observations suggest a newly identified type of hydraulic jump, that is a stratified low Froude number (< 1.5–2) subaqueous hydraulic jump, with an enhanced ability to transport sediment downstream of the jump, in comparison to hydraulic jumps in other subaerial and submarine flows. These novel field data underpin a new process-based conceptual model of channel lobe transition zones (CLTZs) that explains the scattered offset nature of scours within such settings, the temporal variations in infill and erosion between adjacent scours, how bed shear stresses are maintained across the CLTZ, and why the locus of deposition is so far downstream of the scour zone.
Gravity currents, Hydraulic jumps, Stratification, Channel-lobe transition zone
0025-3227
181-193
Dorrell, R.M.
2e8ebfe0-7987-4d2c-a92b-5d79b5135197
Peakall, J.
2351dbf6-2c4f-4250-bacf-fe1b69870f26
Sumner, E.J.
dbba4b92-89cc-45d9-888e-d0e87e5c10ac
Parsons, D.R.
8bc551f4-ae49-48cd-8533-82a34e749d74
Darby, S.E.
4c3e1c76-d404-4ff3-86f8-84e42fbb7970
Wynn, R.B.
72ccd765-9240-45f8-9951-4552b497475a
Ozsoy, E.
2669bb72-3493-4142-a2b2-5ef711ec2c6f
Tezcan, D.
4305ce0e-8d0a-4bff-a821-e6d0b2430a68
Dorrell, R.M.
2e8ebfe0-7987-4d2c-a92b-5d79b5135197
Peakall, J.
2351dbf6-2c4f-4250-bacf-fe1b69870f26
Sumner, E.J.
dbba4b92-89cc-45d9-888e-d0e87e5c10ac
Parsons, D.R.
8bc551f4-ae49-48cd-8533-82a34e749d74
Darby, S.E.
4c3e1c76-d404-4ff3-86f8-84e42fbb7970
Wynn, R.B.
72ccd765-9240-45f8-9951-4552b497475a
Ozsoy, E.
2669bb72-3493-4142-a2b2-5ef711ec2c6f
Tezcan, D.
4305ce0e-8d0a-4bff-a821-e6d0b2430a68

Dorrell, R.M., Peakall, J., Sumner, E.J., Parsons, D.R., Darby, S.E., Wynn, R.B., Ozsoy, E. and Tezcan, D. (2016) Flow dynamics and mixing processes in hydraulic jump arrays: Implications for channel-lobe transition zones Marine Geology, 381, pp. 181-193. (doi:10.1016/j.margeo.2016.09.009).

Record type: Article

Abstract

A detailed field investigation of a saline gravity current in the southwest Black Sea has enabled the first complete analysis of three-dimensional flow structure and dynamics of a series of linked hydraulic jumps in stratified, density-driven, flows. These field observations were collected using an acoustic Doppler current profiler mounted on an autonomous underwater vehicle, and reveal that internal mixing processes in hydraulic jumps, including flow expansion and recirculation, provide a previously unrecognised mechanism for grain-size sorting and segregation in stratified density-driven flows. Field observations suggest a newly identified type of hydraulic jump, that is a stratified low Froude number (< 1.5–2) subaqueous hydraulic jump, with an enhanced ability to transport sediment downstream of the jump, in comparison to hydraulic jumps in other subaerial and submarine flows. These novel field data underpin a new process-based conceptual model of channel lobe transition zones (CLTZs) that explains the scattered offset nature of scours within such settings, the temporal variations in infill and erosion between adjacent scours, how bed shear stresses are maintained across the CLTZ, and why the locus of deposition is so far downstream of the scour zone.

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Accepted/In Press date: 18 September 2016
e-pub ahead of print date: 20 September 2016
Published date: 1 November 2016
Keywords: Gravity currents, Hydraulic jumps, Stratification, Channel-lobe transition zone
Organisations: Geology & Geophysics, Marine Geoscience, Earth Surface Dynamics

Identifiers

Local EPrints ID: 401024
URI: http://eprints.soton.ac.uk/id/eprint/401024
ISSN: 0025-3227
PURE UUID: 58ee0e84-3ce6-4fc6-84eb-ed68c649602e
ORCID for S.E. Darby: ORCID iD orcid.org/0000-0001-8778-4394

Catalogue record

Date deposited: 03 Oct 2016 13:02
Last modified: 09 Jan 2018 17:50

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Contributors

Author: R.M. Dorrell
Author: J. Peakall
Author: E.J. Sumner
Author: D.R. Parsons
Author: S.E. Darby ORCID iD
Author: R.B. Wynn
Author: E. Ozsoy
Author: D. Tezcan

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