Application of short-range dual-Doppler lidars to evaluate the coherence of turbulence

Etienne Cheynet, Jasna Bogunović Jakobsen, Jónas Snæbjörnsson, Torben Krogh Mikkelsen, Mikael Sjöholm, Jakob Mann, Per Hansen, Nikolas Angelou, Benny Svardal

Research output: Contribution to journalJournal articleResearchpeer-review

Abstract

Two synchronized continuous wave scanning lidars are used to study the coherence of the along-wind and across-wind velocity components. The goal is to evaluate the potential of the lidar technology for application in wind engineering. The wind lidars were installed on the Lysefjord Bridge during four days in May 2014 to monitor the wind field in the horizontal plane upstream of the bridge deck. Wind records obtained by five sonic anemometers mounted on the West side of the bridge are used as reference data. Single- and two-point statistics of wind turbulence are studied, with special emphasis on the root-coherence and the co-coherence of turbulence. A four-parameter decaying exponential function has been fitted to the measured co-coherence, and a good agreement is observed between data obtained by the sonic anemometers and the lidars. The root-coherence of turbulence is compared to theoretical models. The analytical predictions agree rather well with the measured coherence for the along-wind component. For increasing wavenumbers, larger discrepancies are, however, noticeable between the measured coherence and the theoretical predictions. The WindScanners are observed to slightly overestimate the integral length scales, which could not be explained by the laser beam averaging effect alone. On the other hand, the spatial averaging effect does not seem to have any significant effect on the coherence.
Original languageEnglish
Article number184
JournalExperiments in Fluids
Volume57
Issue number12
Number of pages17
ISSN0723-4864
DOIs
Publication statusPublished - 2016

Cite this

@article{0552021c8ce04586845fded63da647fb,
title = "Application of short-range dual-Doppler lidars to evaluate the coherence of turbulence",
abstract = "Two synchronized continuous wave scanning lidars are used to study the coherence of the along-wind and across-wind velocity components. The goal is to evaluate the potential of the lidar technology for application in wind engineering. The wind lidars were installed on the Lysefjord Bridge during four days in May 2014 to monitor the wind field in the horizontal plane upstream of the bridge deck. Wind records obtained by five sonic anemometers mounted on the West side of the bridge are used as reference data. Single- and two-point statistics of wind turbulence are studied, with special emphasis on the root-coherence and the co-coherence of turbulence. A four-parameter decaying exponential function has been fitted to the measured co-coherence, and a good agreement is observed between data obtained by the sonic anemometers and the lidars. The root-coherence of turbulence is compared to theoretical models. The analytical predictions agree rather well with the measured coherence for the along-wind component. For increasing wavenumbers, larger discrepancies are, however, noticeable between the measured coherence and the theoretical predictions. The WindScanners are observed to slightly overestimate the integral length scales, which could not be explained by the laser beam averaging effect alone. On the other hand, the spatial averaging effect does not seem to have any significant effect on the coherence.",
author = "Etienne Cheynet and Jakobsen, {Jasna Bogunović} and J{\'o}nas Sn{\ae}bj{\"o}rnsson and Mikkelsen, {Torben Krogh} and Mikael Sj{\"o}holm and Jakob Mann and Per Hansen and Nikolas Angelou and Benny Svardal",
year = "2016",
doi = "10.1007/s00348-016-2275-9",
language = "English",
volume = "57",
journal = "Experiments in Fluids",
issn = "0723-4864",
publisher = "Springer",
number = "12",

}

Application of short-range dual-Doppler lidars to evaluate the coherence of turbulence. / Cheynet, Etienne; Jakobsen, Jasna Bogunović; Snæbjörnsson, Jónas; Mikkelsen, Torben Krogh; Sjöholm, Mikael; Mann, Jakob; Hansen, Per; Angelou, Nikolas; Svardal, Benny.

In: Experiments in Fluids, Vol. 57, No. 12, 184, 2016.

Research output: Contribution to journalJournal articleResearchpeer-review

TY - JOUR

T1 - Application of short-range dual-Doppler lidars to evaluate the coherence of turbulence

AU - Cheynet, Etienne

AU - Jakobsen, Jasna Bogunović

AU - Snæbjörnsson, Jónas

AU - Mikkelsen, Torben Krogh

AU - Sjöholm, Mikael

AU - Mann, Jakob

AU - Hansen, Per

AU - Angelou, Nikolas

AU - Svardal, Benny

PY - 2016

Y1 - 2016

N2 - Two synchronized continuous wave scanning lidars are used to study the coherence of the along-wind and across-wind velocity components. The goal is to evaluate the potential of the lidar technology for application in wind engineering. The wind lidars were installed on the Lysefjord Bridge during four days in May 2014 to monitor the wind field in the horizontal plane upstream of the bridge deck. Wind records obtained by five sonic anemometers mounted on the West side of the bridge are used as reference data. Single- and two-point statistics of wind turbulence are studied, with special emphasis on the root-coherence and the co-coherence of turbulence. A four-parameter decaying exponential function has been fitted to the measured co-coherence, and a good agreement is observed between data obtained by the sonic anemometers and the lidars. The root-coherence of turbulence is compared to theoretical models. The analytical predictions agree rather well with the measured coherence for the along-wind component. For increasing wavenumbers, larger discrepancies are, however, noticeable between the measured coherence and the theoretical predictions. The WindScanners are observed to slightly overestimate the integral length scales, which could not be explained by the laser beam averaging effect alone. On the other hand, the spatial averaging effect does not seem to have any significant effect on the coherence.

AB - Two synchronized continuous wave scanning lidars are used to study the coherence of the along-wind and across-wind velocity components. The goal is to evaluate the potential of the lidar technology for application in wind engineering. The wind lidars were installed on the Lysefjord Bridge during four days in May 2014 to monitor the wind field in the horizontal plane upstream of the bridge deck. Wind records obtained by five sonic anemometers mounted on the West side of the bridge are used as reference data. Single- and two-point statistics of wind turbulence are studied, with special emphasis on the root-coherence and the co-coherence of turbulence. A four-parameter decaying exponential function has been fitted to the measured co-coherence, and a good agreement is observed between data obtained by the sonic anemometers and the lidars. The root-coherence of turbulence is compared to theoretical models. The analytical predictions agree rather well with the measured coherence for the along-wind component. For increasing wavenumbers, larger discrepancies are, however, noticeable between the measured coherence and the theoretical predictions. The WindScanners are observed to slightly overestimate the integral length scales, which could not be explained by the laser beam averaging effect alone. On the other hand, the spatial averaging effect does not seem to have any significant effect on the coherence.

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