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Title: Turbulence Measurements from Compliant Moorings. Part II: Motion Correction

Abstract

Acoustic Doppler velocimeters (ADVs) are a valuable tool for making highprecision measurements of turbulence, and moorings are a convenient and ubiquitous platform for making many kinds of measurements in the ocean. However—because of concerns that mooring motion can contaminate turbulence measurements and acoustic Doppler profilers are relatively easy to deploy—ADVs are not frequently deployed from moorings. This work details a method for measuring turbulence using moored ADVs that corrects for mooring motion using measurements from inertial motion sensors. Three distinct mooring platforms were deployed in a tidal channel with inertial motion-sensor-equipped ADVs. In each case, the motion correction based on the inertial measurements dramatically reduced contamination from mooring motion. The spectra from these measurements have a shape that is consistent with other measurements in tidal channels, and have a f^(5/3) slope at high frequencies—consistent with Kolmogorov’s theory of isotropic turbulence. Motion correction also improves estimates of cross-spectra and Reynold’s stresses. Comparison of turbulence dissipation with flow speed and turbulence production indicates a bottom boundary layer production-dissipation balance during ebb and flood that is consistent with the strong tidal forcing at the site. These results indicate that inertial-motion-sensor-equipped ADVs are a valuable new tool for measuring turbulence from moorings.

Authors:
 [1];  [2];  [3];  [4]
  1. National Renewable Energy Laboratory, Golden, Colorado
  2. Applied Physics Laboratory, University of Washington, Seattle, Washington
  3. Pacific Northwest National Laboratory, Richland, Washington
  4. Nortek AS, Rud, Norway
Publication Date:
Research Org.:
Pacific Northwest National Lab. (PNNL), Richland, WA (United States)
Sponsoring Org.:
USDOE Office of Energy Efficiency and Renewable Energy (EERE)
OSTI Identifier:
1406711
Report Number(s):
PNNL-SA-122270
Journal ID: ISSN 0739-0572; WC0100000
DOE Contract Number:  
AC05-76RL01830
Resource Type:
Journal Article
Resource Relation:
Journal Name: Journal of Atmospheric and Oceanic Technology; Journal Volume: 34; Journal Issue: 6
Country of Publication:
United States
Language:
English

Citation Formats

Kilcher, Levi F., Thomson, Jim, Harding, Samuel, and Nylund, Sven. Turbulence Measurements from Compliant Moorings. Part II: Motion Correction. United States: N. p., 2017. Web. doi:10.1175/JTECH-D-16-0213.1.
Kilcher, Levi F., Thomson, Jim, Harding, Samuel, & Nylund, Sven. Turbulence Measurements from Compliant Moorings. Part II: Motion Correction. United States. doi:10.1175/JTECH-D-16-0213.1.
Kilcher, Levi F., Thomson, Jim, Harding, Samuel, and Nylund, Sven. Thu . "Turbulence Measurements from Compliant Moorings. Part II: Motion Correction". United States. doi:10.1175/JTECH-D-16-0213.1.
@article{osti_1406711,
title = {Turbulence Measurements from Compliant Moorings. Part II: Motion Correction},
author = {Kilcher, Levi F. and Thomson, Jim and Harding, Samuel and Nylund, Sven},
abstractNote = {Acoustic Doppler velocimeters (ADVs) are a valuable tool for making highprecision measurements of turbulence, and moorings are a convenient and ubiquitous platform for making many kinds of measurements in the ocean. However—because of concerns that mooring motion can contaminate turbulence measurements and acoustic Doppler profilers are relatively easy to deploy—ADVs are not frequently deployed from moorings. This work details a method for measuring turbulence using moored ADVs that corrects for mooring motion using measurements from inertial motion sensors. Three distinct mooring platforms were deployed in a tidal channel with inertial motion-sensor-equipped ADVs. In each case, the motion correction based on the inertial measurements dramatically reduced contamination from mooring motion. The spectra from these measurements have a shape that is consistent with other measurements in tidal channels, and have a f^(5/3) slope at high frequencies—consistent with Kolmogorov’s theory of isotropic turbulence. Motion correction also improves estimates of cross-spectra and Reynold’s stresses. Comparison of turbulence dissipation with flow speed and turbulence production indicates a bottom boundary layer production-dissipation balance during ebb and flood that is consistent with the strong tidal forcing at the site. These results indicate that inertial-motion-sensor-equipped ADVs are a valuable new tool for measuring turbulence from moorings.},
doi = {10.1175/JTECH-D-16-0213.1},
journal = {Journal of Atmospheric and Oceanic Technology},
number = 6,
volume = 34,
place = {United States},
year = {Thu Jun 01 00:00:00 EDT 2017},
month = {Thu Jun 01 00:00:00 EDT 2017}
}