Spectral measurement of water particle velocities under waves
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Authors
Bordy, Michael William
Subjects
Advisors
Thornton, Edward B.
Date of Issue
1972-03
Date
Publisher
Monterey, California. Naval Postgraduate School
Language
en_US
Abstract
Simultaneous measurements of the instantaneous sea
surface elevation and water particle velocities were made
using a wave staff and an electromagnetic current meter.
Measurements were made at three elevations in 18 meters
of water at an open ocean site during moderate wave and
wind conditions . Coherence of the wave height and orbital
velocities was computed to be greater than 0.90 through
the range of significant energy-density between 0.05 and
0.22 Hertz. This range contained greater than 90 percent
of the total spectral energy-density which indicated that
the water particle velocities were almost totally waveinduced.
Measured velocity energy-density spectra were
compared to theoretically computed spectra using linear
wave theory formulation. The measured spectra were 27 to
45 percent greater than theoretical spectra indicating
that measured velocities were 5 to 7 percent greater than
the theoretical value. Phase spectra were computed for
the measured wave heights and orbital velocities. They
compared reasonably with first order wave theory.
Type
Thesis
Description
Series/Report No
Department
Organization
Naval Postgraduate School
Identifiers
NPS Report Number
Sponsors
Funding
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Citation
Distribution Statement
Approved for public release; distribution is unlimited.