Effects of current on wind waves in strong winds
<p>It is important to investigate the effects of current on wind waves, called the Doppler shift, at both normal and extremely high wind speeds. Three different types of wind-wave tanks along with a fan and pump are used to demonstrate wind waves and currents in laboratories at Kyoto Universit...
| Main Authors: | , , , , , |
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| Format: | Article |
| Language: | English |
| Published: |
Copernicus Publications
2020-09-01
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| Series: | Ocean Science |
| Online Access: | https://os.copernicus.org/articles/16/1033/2020/os-16-1033-2020.pdf |
| _version_ | 1829492346660585472 |
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| author | N. Takagaki N. Suzuki Y. Troitskaya C. Tanaka A. Kandaurov M. Vdovin |
| author_facet | N. Takagaki N. Suzuki Y. Troitskaya C. Tanaka A. Kandaurov M. Vdovin |
| author_sort | N. Takagaki |
| collection | DOAJ |
| description | <p>It is important to investigate the effects of current on wind waves, called
the Doppler shift, at both normal and extremely high wind speeds. Three
different types of wind-wave tanks along with a fan and pump are used to
demonstrate wind waves and currents in laboratories at Kyoto University,
Japan, Kindai University, Japan, and the Institute of Applied Physics,
Russian Academy of Sciences, Russia. Profiles of the wind and current
velocities and the water-level fluctuation are measured. The wave frequency,
wavelength, and phase velocity of the significant waves are calculated, and
the water velocities at the water surface and in the bulk of the water are
also estimated by the current distribution. The study investigated 27 cases
with measurements of winds, waves, and currents at wind speeds ranging
from 7 to 67 m s<span class="inline-formula"><sup>−1</sup></span>. At normal wind speeds under 30 m s<span class="inline-formula"><sup>−1</sup></span>, wave
frequency, wavelength, and phase velocity depend on wind speed and fetch.
The effect of the Doppler shift is confirmed at normal wind speeds; i.e.,
the significant waves are accelerated by the surface current. The phase
velocity can be represented as the sum of the surface current and artificial
phase velocity, which is estimated by the dispersion relation of the
deepwater waves. At extremely high wind speeds over 30 m s<span class="inline-formula"><sup>−1</sup></span>, a similar
Doppler shift is observed as under the conditions of normal wind speeds.
This suggests that the Doppler shift is an adequate model for representing
the acceleration of wind waves by current, not only for wind waves at
normal wind speeds but also for those with intensive breaking at extremely
high wind speeds. A weakly nonlinear model of surface waves at a shear flow
is developed. It is shown that it describes dispersion properties well
not only for small-amplitude waves but also strongly nonlinear and even
breaking waves, which are typical for extreme wind conditions (over 30 m s<span class="inline-formula"><sup>−1</sup></span>).</p> |
| first_indexed | 2024-12-16T06:13:18Z |
| format | Article |
| id | doaj.art-3c0d456c159e465082b4745509cb89c3 |
| institution | Directory Open Access Journal |
| issn | 1812-0784 1812-0792 |
| language | English |
| last_indexed | 2024-12-16T06:13:18Z |
| publishDate | 2020-09-01 |
| publisher | Copernicus Publications |
| record_format | Article |
| series | Ocean Science |
| spelling | doaj.art-3c0d456c159e465082b4745509cb89c32022-12-21T22:41:20ZengCopernicus PublicationsOcean Science1812-07841812-07922020-09-01161033104510.5194/os-16-1033-2020Effects of current on wind waves in strong windsN. Takagaki0N. Suzuki1Y. Troitskaya2C. Tanaka3A. Kandaurov4M. Vdovin5Department of Mechanical Engineering, University of Hyogo, Shosha 2167, Himeji Hyogo, 671-2280, JapanFaculty of Science and Engineering, Kindai University, 3-4-1, Kowakae Higashiosaka Osaka, 577-8502, JapanDepartment of Geophysical Research, Institute of Applied Physics, the Russian Academy of Sciences, 46 Ul'yanov Street, Nizhny Novgorod, 603-950, RussiaFaculty of Science and Engineering, Kindai University, 3-4-1, Kowakae Higashiosaka Osaka, 577-8502, JapanDepartment of Geophysical Research, Institute of Applied Physics, the Russian Academy of Sciences, 46 Ul'yanov Street, Nizhny Novgorod, 603-950, RussiaDepartment of Geophysical Research, Institute of Applied Physics, the Russian Academy of Sciences, 46 Ul'yanov Street, Nizhny Novgorod, 603-950, Russia<p>It is important to investigate the effects of current on wind waves, called the Doppler shift, at both normal and extremely high wind speeds. Three different types of wind-wave tanks along with a fan and pump are used to demonstrate wind waves and currents in laboratories at Kyoto University, Japan, Kindai University, Japan, and the Institute of Applied Physics, Russian Academy of Sciences, Russia. Profiles of the wind and current velocities and the water-level fluctuation are measured. The wave frequency, wavelength, and phase velocity of the significant waves are calculated, and the water velocities at the water surface and in the bulk of the water are also estimated by the current distribution. The study investigated 27 cases with measurements of winds, waves, and currents at wind speeds ranging from 7 to 67 m s<span class="inline-formula"><sup>−1</sup></span>. At normal wind speeds under 30 m s<span class="inline-formula"><sup>−1</sup></span>, wave frequency, wavelength, and phase velocity depend on wind speed and fetch. The effect of the Doppler shift is confirmed at normal wind speeds; i.e., the significant waves are accelerated by the surface current. The phase velocity can be represented as the sum of the surface current and artificial phase velocity, which is estimated by the dispersion relation of the deepwater waves. At extremely high wind speeds over 30 m s<span class="inline-formula"><sup>−1</sup></span>, a similar Doppler shift is observed as under the conditions of normal wind speeds. This suggests that the Doppler shift is an adequate model for representing the acceleration of wind waves by current, not only for wind waves at normal wind speeds but also for those with intensive breaking at extremely high wind speeds. A weakly nonlinear model of surface waves at a shear flow is developed. It is shown that it describes dispersion properties well not only for small-amplitude waves but also strongly nonlinear and even breaking waves, which are typical for extreme wind conditions (over 30 m s<span class="inline-formula"><sup>−1</sup></span>).</p>https://os.copernicus.org/articles/16/1033/2020/os-16-1033-2020.pdf |
| spellingShingle | N. Takagaki N. Suzuki Y. Troitskaya C. Tanaka A. Kandaurov M. Vdovin Effects of current on wind waves in strong winds Ocean Science |
| title | Effects of current on wind waves in strong winds |
| title_full | Effects of current on wind waves in strong winds |
| title_fullStr | Effects of current on wind waves in strong winds |
| title_full_unstemmed | Effects of current on wind waves in strong winds |
| title_short | Effects of current on wind waves in strong winds |
| title_sort | effects of current on wind waves in strong winds |
| url | https://os.copernicus.org/articles/16/1033/2020/os-16-1033-2020.pdf |
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