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Observations of large-scale coherent structures in gravity currents: implications for flow dynamics

Marshall, C. R.; Dorrell, R. M.; Keevil, G. M.; Peakall, J.; Tobias, S. M.


C. R. Marshall

G. M. Keevil

J. Peakall

S. M. Tobias


Density driven flows, also known as gravity currents, comprise a head, body, and tail. Yet whilst the body typically forms the largest part of such flows, its structure remains poorly understood. In this work, experimental data gathered using particle image velocimetry enables the instantaneous, whole-field dynamics of constant-influx solute-based gravity currents to be resolved. While averaged turbulent kinetic energy profiles are comparable to previous work, the instantaneous data sets reveal significant temporal variation, with velocity measurements indicating large-scale wave-like motions within the body. Spectral analysis and dynamic mode decomposition, of streamwise and vertical velocity, are used to identify the frequencies and structures of the dominant motions within the flow. By considering an idealised theoretical density profile, it is suggested that these structures may be internal gravity waves that form a critical layer within the flow located at the height of the maximum internal velocity. Irreversible internal wave breaking that has been postulated to occur at this critical layer suggests formation of internal eddy transport barriers, demonstrating that new dynamic models of turbulent mixing in gravity currents are needed.


Marshall, C. R., Dorrell, R. M., Keevil, G. M., Peakall, J., & Tobias, S. M. (2021). Observations of large-scale coherent structures in gravity currents: implications for flow dynamics. Experiments in Fluids, 62(6), Article 120.

Journal Article Type Article
Acceptance Date Apr 24, 2021
Online Publication Date May 17, 2021
Publication Date 2021-06
Deposit Date Jul 22, 2021
Publicly Available Date Jul 22, 2021
Journal Experiments in Fluids
Print ISSN 0723-4864
Electronic ISSN 1432-1114
Publisher Springer
Peer Reviewed Peer Reviewed
Volume 62
Issue 6
Article Number 120
Keywords General Physics and Astronomy; Mechanics of Materials; Fluid Flow and Transfer Processes; Computational Mechanics
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© The Author(s) 2021.<br /> Open AccessThis article is licensed under a Creative Commons Attribution 4.0 International License, which permits use, sharing, adaptation, distribution and reproduction in any medium or format, as long as you give appropriate credit to the original author(s) and the source, provide a link to the Creative Commons licence, and indicate if changes were made. The images or other third party material in this article are included in the article’s Creative Commons licence, unless indicated otherwise in a credit line to the material. If material is not included in the article’s Creative Commons licence and your intended use is not permitted by statutory regulation or exceeds the permitted use, you will need to obtain permission directly from the copyright holder. To view a copy of this licence, visit

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