Coastal and Laboratory Wavestaff System

Flick, Reinhard E.; Lowe, R. B.; Freilich, Michael H.; Boylls, J.

doi:10.1109/oceans.1979.1151229

Cited by 8 publications

(4 citation statements)

References 2 publications

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“…Although generally used in laboratory conditions (Flick et al, ), capacitance and resistive types of wave gauges were used very early in the field to estimate surface elevation spectra in the shoaling region (Tucker & Charnock, ; Simpson, ; Flick et al, ) and in the surf zone (Thornton et al, ; Gonçalo, ; Thornton & Guza, ). More information on this type of gauges can be found in Flick et al (), Shand et al (), and the references therein. When calibrated, these gauges allow

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(mm) accuracy in controlled environments; however, the presence of large pockets or fractions of air under breaking waves potentially leads to large errors in the estimation of the free surface, or at least its envelop.…”

Section: In Situ Methods For Characterizing Non‐hydrostatic Wave Procmentioning

confidence: 99%

“…The presence of splashes around the poles (Ibaceta et al, 2018) and the errors associated with the pixel resolution limit the accuracy of the measurements to several centimeters in the surf zone. Although generally used in laboratory conditions (Flick et al, 1981), capacitance and resistive types of wave gauges were used very early in the field to estimate surface elevation spectra in the shoaling region (Tucker & Charnock, 1954;Simpson, 1969;Flick et al, 1979) and in the surf zone (Thornton et al, 1976;Gonçalo, 1978;Thornton & Guza, 1983). More information on this type of gauges can be found in Flick et al (1979), Shand et al (2009), and the references therein.…”

Section: Direct Measurements Of Surf Zone Wavesmentioning

confidence: 99%

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Non‐hydrostatic, Non‐linear Processes in the Surf Zone

et al. 2020

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In the surf zone, non‐hydrostatic processes are either neglected or estimated using linear wave theory. The recent development of technologies capable of directly measuring the free surface elevation, such as 2‐D lidar scanners, allow for a thorough assessment of the validity of such hypotheses. In this study, we use subsurface pressure and lidar data to study the non‐linear and non‐hydrostatic character of surf zone waves. Non‐hydrostatic effects are found important everywhere in the surf zone (from the outer to the inner surf zones). Surface elevation variance, skewness, and asymmetry estimated from the hydrostatic reconstruction are found to significantly underestimate the values obtained from the lidar data. At the wave‐by‐wave scale, this is explained by the underestimation of the wave crest maximal elevations, even in the inner surf zone, where the wave profile around the broken wave face is smoothed. The classic transfer function based on linear wave theory brings only marginal improvements in this regard, compared to the hydrostatic reconstruction. A recently developed non‐linear weakly dispersive reconstruction is found to consistently outperform the hydrostatic or classic transfer function reconstructions over the entire surf zone, with relative errors on the surface elevation variance and skewness around 5% on average. In both the outer and inner surf zones, this method correctly reproduces the steep front of breaking and broken waves and their individual wave height to within 10%. The performance of this irrotational method supports the hypothesis that the flow under broken waves is dominated by irrotational motions.

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Section: In Situ Methods For Characterizing Non‐hydrostatic Wave Procmentioning

confidence: 99%

Section: Direct Measurements Of Surf Zone Wavesmentioning

confidence: 99%

Non‐hydrostatic, Non‐linear Processes in the Surf Zone

et al. 2020

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“…The wavestaff array was designed to measure properties of the Kelvin wake features, including wave height, slope, and propagation direction. Sixteen single resistancewire wavestaffs were selected for the instrument array based on the relative simplicity of deployment and low cost (Flick et at. 1979).…”

Section: The Wavestaff Arraymentioning

confidence: 99%

Observations of a nonlinear solitary wave packet in the Kelvin wake of a ship

et al. 1989

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Thirty data sets of wavestaff measurements of a solitary feature in the Kelvin wake of the Coast Guard cutter Point Brower are analysed. The average characteristics of the feature between 1 and 4 km aft of the ship are shown to be consistent with those of an oblique nonlinear solitary wave packet. The ship speed is 7.7 m/s (Froude number 0.49) and the waves that comprise the packet have an average frequency of 3.28 rad/s. The ship speed and the wave frequency, together with Kelvin wake kinematics, imply that the feature appears at an average wake half-angle of 10.9°. The packet does not exhibit linear dispersion beyond 1 km aft of the ship and its average width is 8.9 m (measured at e−1 of the peak variance). The average amplitude is 1.1 times the theoretical amplitude of an oblique nonlinear solitary wave packet with the observed width. There is considerable variability from run to run, and there is evidence of dispersive spreading before 1 km aft of the ship. An aerial photograph shows a sinuous fluctuation of the feature; possible explanations for the fluctuation include small variations in initial conditions or a sinuous instability. The solitary feature is a possible explanation for the long bright lines observed in SEASAT SAR images in light to moderate winds and observed in sun glitter photos taken from the space shuttle.

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“…The measurements were conducted in the Scripps Institution of Oceanography Hydraulics Laboratory. Figure 2 illustrates schematically the 30 m glass wall wave channel, the high-pressure servo-hydraulic wavemaker system and the high resolution resistance wire wavestaff system (Flick, et al, 1979) used in the study.…”

Section: Introductionmentioning

confidence: 99%

Two-Dimensional Surf Beat

Flick

Inman

Guza

1980

Int. Conf. Coastal. Eng.

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Surface elevation and velocity measurements in shallow water on beaches show large fluctuations known as surf beat in the long period range from approximately 20s to 2000s (Munk, 1949; Tucker, 1950). A laboratory study was conducted to determine if two shoaling primary waves of nearly equal frequency would generate two-dimensional surf beat at their difference frequency. The experiments, carried out in the Scripps Institution of Oceanography Hydraulics Laboratory 30 m glass walled wave channel, show that the beat frequency motion in the channel consists of the sum of a forced progressive wave and two free standing waves. The progressive wave is forced by the local nonlinear interaction of the primary waves and grows sharply in shallow water. One of the free standing waves is generated directly by the wavemaker. The data is consistent with the hypotheses that the second, much larger, free wave is generated in shallow water as the reflection of the long, forced progressive wave, leading to the observed standing wave surf beat pattern.

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Coastal and Laboratory Wavestaff System

Cited by 8 publications

References 2 publications

Non‐hydrostatic, Non‐linear Processes in the Surf Zone

Non‐hydrostatic, Non‐linear Processes in the Surf Zone

Observations of a nonlinear solitary wave packet in the Kelvin wake of a ship

Two-Dimensional Surf Beat

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