Keylock, CJ, Nishimura, K and Peinke, J (2012) A classification scheme for turbulence based on the velocity-intermittency structure with an application to near-wall flow and with implications for bedload transport. Journal of Geophysical Research, 117 (F1).
Abstract
Kolmogorov's classic theory for turbulence assumed an independence between velocity increments and the value for the velocity itself. However, recent work has called this assumption in to question, which has implications for the structure of atmospheric, oceanic and fluvial flows. Here we propose a conceptually simple analytical framework for studying velocity-intermittency coupling that is similar in essence to the popular quadrant analysis method for studying near-wall flows. However, we study the dominant (longitudinal) velocity component along with a measure of the roughness of the signal, given mathematically by its series of Hölder exponents. Thus, we permit a possible dependence between velocity and intermittency. We compare boundary layer data obtained in a wind tunnel to turbulent jets and wake flows. These flow classes all have distinct characteristics, which cause them to be readily distinguished using our technique and the results are robust to changes in flow Reynolds numbers. Classification of environmental flows is then possible based on their similarities to the idealized flow classes and we demonstrate this using laboratory data for flow in a parallel-channel confluence. Our results have clear implications for sediment transport in a range of geophysical applications as they suggest that the recently proposed impulse-based methods for studying bed load transport are particularly relevant in domains such as gravel bed river flows where the boundary layer is disrupted and wake interactions predominate.
Metadata
Item Type: | Article |
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Authors/Creators: |
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Copyright, Publisher and Additional Information: | © 2012. American Geophysical Union. Reproduced in accordance with the publisher's self-archiving policy. |
Keywords: | Flow classification; Flow structures; Intermittency; Sediment transport; Turbulence. |
Dates: |
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Institution: | The University of Sheffield |
Academic Units: | The University of Sheffield > Faculty of Engineering (Sheffield) > Department of Civil and Structural Engineering (Sheffield) |
Depositing User: | Symplectic Sheffield |
Date Deposited: | 23 Apr 2014 11:23 |
Last Modified: | 29 Mar 2018 03:00 |
Published Version: | http://dx.doi.org/10.1029/2011JF002127 |
Status: | Published |
Publisher: | American Geophysical Union |
Identification Number: | 10.1029/2011JF002127 |
Open Archives Initiative ID (OAI ID): | oai:eprints.whiterose.ac.uk:78411 |