Dynamic Selection of Exposure Time for Turbulent Flow Measurements
Publication: Journal of Hydraulic Engineering
Volume 147, Issue 10
Abstract
The selection of optimum sampling configurations to measure the aspects of turbulent flow of water depends on the variable being measured, the applied measurement technique, the degree of environmental noise, and flow characteristics in and near the sampling location. This work presents a method to dynamically select the exposure time (SET) during the flow-velocity measurement at each sampling location on the basis of the moving block bootstrap (MBB) technique. The MBB enables near real-time estimation of the confidence intervals and, subsequently, the COV for turbulence parameters. The dynamic SET method has been tested in this work using time series of synthetic turbulent flow-velocity signals. This method was implemented using actual flow-velocity signals recorded with acoustic Doppler velocity (ADVs) instruments and acoustic Doppler current profilers (ADCPs). The results obtained from the implementation of the dynamic SET method show that the sampling time to achieve a defined uncertainty threshold is not the same for different turbulence parameters. Consequently, using the dynamic SET method, the exposure time can be optimized to obtain the turbulence parameters with the required uncertainty level. The dynamic SET method can be implemented in the instrument’s data logger to dynamically select the exposure time during flow measurements for a given uncertainty of the required turbulence parameter.
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Data Availability Statement
The data files of the measurements used in this paper are available from the USGS data release by Oberg et al. (2021) (https://doi.org/10.5066/P9RQPHQL).
Acknowledgments
Disclaimer
The use of trade, firm, or product names is for descriptive purposes only and does not imply endorsement by the US Government. Nor does it constitute or imply endorsement, recommendation, or warranty thereof by the authors.
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Published In
Journal of Hydraulic Engineering
Volume 147 • Issue 10 • October 2021
Copyright
© 2021 American Society of Civil Engineers.
History
Received: Aug 18, 2020
Accepted: May 3, 2021
Published online: Jul 27, 2021
Published in print: Oct 1, 2021
Discussion open until: Dec 27, 2021
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