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Earth Surface Dynamics An interactive open-access journal of the European Geosciences Union

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Earth Surf. Dynam., 5, 399-415, 2017
https://doi.org/10.5194/esurf-5-399-2017
© Author(s) 2017. This work is distributed under
the Creative Commons Attribution 3.0 License.
Research article
19 Jul 2017
The influence of turbulent bursting on sediment resuspension under unidirectional currents
Sarik Salim1, Charitha Pattiaratchi1, Rafael Tinoco2, Giovanni Coco3, Yasha Hetzel1, Sarath Wijeratne1, and Ravindra Jayaratne4 1School of Civil Environmental and Mining Engineering and UWA Oceans Institute, University of Western Australia, 35 Stirling Highway, Crawley, WA 6009, Australia
2Department of Civil and Environmental Engineering, University of Illinois at Urbana-Champaign, Urbana, IL 61801, USA
3Faculty of Science, University of Auckland, Auckland 1142, New Zealand
4School of Architecture, Computing and Engineering, University of East London, Docklands Campus, 4–6 University Way, London, E16 2RD, UK
Abstract. Laboratory experiments were conducted in an open channel flume with a flat sandy bed to examine the role of turbulence on sediment resuspension. An acoustic Doppler velocimeter (ADV) was used to measure the instantaneous three-dimensional velocity components and acoustic backscatter as a proxy to suspended sediment concentration. Estimates of sediment transport assume that there is a mean critical velocity that needs to be exceeded before sediment transport is initiated. This approach does not consider the turbulent flow field that may initiate sediment resuspension through event-based processes such as the bursting phenomenon. In this paper, laboratory measurements were used to examine the sediment resuspension processes below and above the mean critical velocity. The results within a range above and below the measured mean critical velocity suggested that (1) the contribution of turbulent bursting events remained identical in both experimental conditions, (2) ejection and sweep events contributed more to the total sediment flux than up-acceleration and down-deceleration events, and (3) wavelet transform revealed a correlation between the momentum and sediment flux in both test conditions. Such similarities in conditions above and below the measured mean critical velocity highlight the need to re-evaluate the accuracy of a single time-averaged mean critical velocity for the initiation of sediment entrainment.

Citation: Salim, S., Pattiaratchi, C., Tinoco, R., Coco, G., Hetzel, Y., Wijeratne, S., and Jayaratne, R.: The influence of turbulent bursting on sediment resuspension under unidirectional currents, Earth Surf. Dynam., 5, 399-415, https://doi.org/10.5194/esurf-5-399-2017, 2017.
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Short summary
The aim of this paper was to verify the existence of a mean critical velocity concept in terms of turbulent bursting phenomena. Laboratory experiments were undertaken in a unidirectional current flume where an acoustic Doppler velocimeter was used. Results in the laboratory conditions both above and below the measured mean critical velocity highlighted the need to re-evaluate the accuracy of a single time-averaged critical velocity for the initiation of sediment entrainment.
The aim of this paper was to verify the existence of a mean critical velocity concept in terms...
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