NDLI: Results of a high-resolution correlation current profiler

Content Provider	IEEE Xplore Digital Library
Author	van Unen, R.F. Kamminga, S.D. Nijveldt, D.
Copyright Year	1997
Description	Author affiliation: Oceanogr. Co. of the Netherlands, Netherlands (van Unen, R.F.)
Abstract	Sedimentologists have great interest in measuring flow velocity profiles close to the seabed, as the sediment is transported mainly in the half a meter above the seabed. Existing measurement instruments cannot measure that close to the seabed (e.g. ADCPs) or measure only in a single point. A technique named the 'correlation technique' is proposed. By means of volume back-scattering acoustic echoes of pairs of transducers, orientated vertically downward, are correlated. This technique is currently capable of providing a vertical resolution of 0.015 m and produces a flow velocity profile down to the seabed. The measurement range includes the complete lower meter of the vertical. As it is a remote sensing technique, no local disturbance of the flow is expected as it is with (multiple) point measurements in frames. The time resolution is at most 5 s, giving instantaneous estimates along the whole vertical at the given spatial resolution. This method has been tested under a variety of-experimental conditions over the last few years. This paper focuses on laboratory flume experiments. Flow velocity, concentration of suspended sand, turbulence intensity, acoustic bin size, type of transmitted signals and estimation times (time resolution) have been varied. The method works fine for small 0.015 m up to large 0.240 m acoustic bin sizes. Typical mean velocity standard deviation is better than 1.5%. Results are compared with an immersible laser Doppler anemometer. The technique proves to be insensitive to turbulence intensities. Different suspended sand concentrations lead to different correlation characteristics without degrading results. Estimates derived from clean water (tap water) results even are the most accurate. The methods will be tested and evaluated under nonstationary flow conditions and in the field in the near future.
Starting Page	477
Ending Page	482
File Size	635708
Page Count	6
File Format	PDF
ISBN	0780341082
DOI	10.1109/OCEANS.1997.634411
Language	English
Publisher	Institute of Electrical and Electronics Engineers, Inc. (IEEE)
Publisher Date	1997-10-06
Publisher Place	Canada
Access Restriction	Subscribed
Rights Holder	Institute of Electrical and Electronics Engineers, Inc. (IEEE)
Subject Keyword	Acoustic measurements Fluid flow measurement Spatial resolution Velocity measurement Sediments Instruments Acoustic transducers Remote sensing Acoustic testing Laboratories
Content Type	Text
Resource Type	Article

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1	Ministry of Education (GoI), Department of Higher Education	Sanctioning Authority	https://www.education.gov.in/ict-initiatives
2	Indian Institute of Technology Kharagpur	Host Institute of the Project: The host institute of the project is responsible for providing infrastructure support and hosting the project	https://www.iitkgp.ac.in
3	National Digital Library of India Office, Indian Institute of Technology Kharagpur	The administrative and infrastructural headquarters of the project	Dr. B. Sutradhar bsutra@ndl.gov.in
4	Project PI / Joint PI	Principal Investigator and Joint Principal Investigators of the project	Dr. B. Sutradhar bsutra@ndl.gov.in Prof. Saswat Chakrabarti will be added soon
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