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Self-sharpening induces jet-like structure in seafloor gravity currents

Self-sharpening induces jet-like structure in seafloor gravity currents
Self-sharpening induces jet-like structure in seafloor gravity currents
Gravity currents are the primary means by which sediments, solutes and heat are transported across the ocean-floor. Existing theory of gravity current flow employs a statistically-stable model of turbulent diffusion that has been extant since the 1960s. Here we present the first set of detailed spatial data from a gravity current over a rough seafloor that demonstrate that this existing paradigm is not universal. Specifically, in contrast to predictions from turbulent diffusion theory, self-sharpened velocity and concentration profiles and a stable barrier to mixing are observed. Our new observations are explained by statistically-unstable mixing and self-sharpening, by boundary-induced internal gravity waves; as predicted by recent advances in fluid dynamics. Self-sharpening helps explain phenomena such as ultra-long runout of gravity currents and restricted growth of bedforms, and highlights increased geohazard risk to marine infrastructure. These processes likely have broader application, for example to wave-turbulence interaction, and mixing processes in environmental flows.
1-10
Dorrell, R.M.
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Peakall, J.
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Darby, S.E.
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Parsons, D.R.
59f2673a-9c73-437a-8865-52d52830a3aa
Johnson, J.
f48f8383-6cd5-45a6-8897-4551e7b9a69c
Sumner, E.J.
dbba4b92-89cc-45d9-888e-d0e87e5c10ac
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
Darby, S.E.
4c3e1c76-d404-4ff3-86f8-84e42fbb7970
Parsons, D.R.
59f2673a-9c73-437a-8865-52d52830a3aa
Johnson, J.
f48f8383-6cd5-45a6-8897-4551e7b9a69c
Sumner, E.J.
dbba4b92-89cc-45d9-888e-d0e87e5c10ac
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., Darby, S.E., Parsons, D.R., Johnson, J., Sumner, E.J., Wynn, R.B., Ozsoy, E. and Tezcan, D. (2019) Self-sharpening induces jet-like structure in seafloor gravity currents. Nature Communications, 10 (1381), 1-10. (doi:10.1038/s41467-019-09254-2).

Record type: Article

Abstract

Gravity currents are the primary means by which sediments, solutes and heat are transported across the ocean-floor. Existing theory of gravity current flow employs a statistically-stable model of turbulent diffusion that has been extant since the 1960s. Here we present the first set of detailed spatial data from a gravity current over a rough seafloor that demonstrate that this existing paradigm is not universal. Specifically, in contrast to predictions from turbulent diffusion theory, self-sharpened velocity and concentration profiles and a stable barrier to mixing are observed. Our new observations are explained by statistically-unstable mixing and self-sharpening, by boundary-induced internal gravity waves; as predicted by recent advances in fluid dynamics. Self-sharpening helps explain phenomena such as ultra-long runout of gravity currents and restricted growth of bedforms, and highlights increased geohazard risk to marine infrastructure. These processes likely have broader application, for example to wave-turbulence interaction, and mixing processes in environmental flows.

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Accepted/In Press date: 26 February 2019
e-pub ahead of print date: 27 March 2019

Identifiers

Local EPrints ID: 429485
URI: https://eprints.soton.ac.uk/id/eprint/429485
PURE UUID: ffc2e9a9-b886-4dfe-b38d-030e237e18a7
ORCID for S.E. Darby: ORCID iD orcid.org/0000-0001-8778-4394

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Date deposited: 27 Mar 2019 17:30
Last modified: 20 Jul 2019 01:13

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