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Water 2018, 10(9), 1246; https://doi.org/10.3390/w10091246

Coupling of Ultrasonic and Photometric Techniques for Synchronous Measurements of Unconfined Turbidity Currents

1
Water Engineering, Tonkin & Taylor Ltd., Auckland 1023, New Zealand
2
Department of Civil and Environmental Engineering, University of Auckland, Auckland 1142, New Zealand
Formerly Department of Civil and Environmental Engineering, University of Auckland.
*
Author to whom correspondence should be addressed.
Received: 13 May 2018 / Revised: 7 September 2018 / Accepted: 12 September 2018 / Published: 14 September 2018
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Abstract

By synchronizing data collection, such as photometric and ultrasonic Doppler profiling (UVP) measurement techniques, new insights can be obtained into environmental flows, such as highly dynamic turbidity currents. We introduce a combined experimental setup, which ultimately allows a time reduction in testing programmes, and discuss the measurement advances with the help of four surface conditions we tested for unconfined turbidity currents: (a) a smooth surface; (b) a smooth surface with an obstacle present; (c) a rough surface; and (d) a rough surface with an obstacle present. We show that data from both measurement techniques indicate that a rough surface reduces global current velocities and the magnitude of turbidity current phenomena, including Kelvin-Helmholtz instabilities and lobe-and-cleft formation. However, by coupling the techniques, photometric data give valuable insight into the spatial development of instabilities, such as the grouping of lobe and cleft formations. The presence of an obstacle causes local regions of an increased and decreased velocity, but does not affect the global current velocity. Additionally, the obstacle created three local intensity maxima upstream, dissipating to two maxima downstream, supporting the presence of local eddies. The study shows that the combination of UVP and photometry is an effective way forward for obtaining detailed qualitative and quantitative insights into turbulent flow characteristics and we highlight the potential for future research. View Full-Text
Keywords: turbidity current; photometry; UVP; fluid mechanics; sediment; hydraulic model turbidity current; photometry; UVP; fluid mechanics; sediment; hydraulic model
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This is an open access article distributed under the Creative Commons Attribution License which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited. (CC BY 4.0).
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Wilson, R.I.; Friedrich, H. Coupling of Ultrasonic and Photometric Techniques for Synchronous Measurements of Unconfined Turbidity Currents. Water 2018, 10, 1246.

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