Field observations of long-period, surf-zone standing waves in relation to contrasting beach morphologies

1982 ◽  
Vol 33 (2) ◽  
pp. 181 ◽  
Author(s):  
LD Wright
Keyword(s):  
Surf Zone ◽  
Full Range ◽  
Wave Length ◽  
Standing Waves ◽  
Wide Band ◽  
Field Observations ◽  
Edge Waves ◽  
Long Period ◽  
Energy Height ◽  
Velocity Spectra

Field observations of water-surface oscillation and horizontal flow velocity spectra were carried out in the surf zones of contrasting beach-inshore morphodynamic states. The observations were made under conditions of long-period (7.5-11 s), moderate-energy (height 1 .2-2.3 m) swell on different beaches encompassing the full range of states from the steep. reflective extreme to the flat, dissipative extreme and including intermediate states involving different scales of rhythmic surf-zone topography and rip circulations. Experiments on all types of topography reveal standing surf-zone oscillations at periods longer than incident wave period. At least some of these appear to be edge waves. The actual frequencies are dependent on the morphodynamic state of the surf zone and beach. The standing waves with shortest period are zero-mode subharmonic edge waves which consistently occur on highly reflective beaches where they cause cusps spaced at one-half the edge-wave length. The standing waves with lowest frequency were observed on the flattest and most dissipative beach and comprised a wide band of infragravity frequencies. These oscillations could cause the multiple parallel bars. Intermediate frequencies occur in the presence of the pronounced bar-trough and rhythmic topographies of intermediate morphodynamic states.

scholarly journals ON PREDICTING INFRAGRAVITY ENERGY IN THE SURF ZONE

1984 ◽  
Vol 1 (19) ◽  
pp. 130
Author(s):  
Asbury H. Sallenger ◽  
Robert A. Holman
Keyword(s):  
Incident Wave ◽  
Surf Zone ◽  
Standing Waves ◽  
Wave Mode ◽  
Edge Wave ◽  
Flow Data ◽  
Edge Waves ◽  
Infragravity Waves ◽  
Synthetic Spectra ◽  
Wave Conditions

Flow data were obtained in the surf zone across a barred profile during a storm. RMS cross-shore velocities due to waves in the infragravity band (wave periods greater than 20 s) had maxima in excess of 0.5 m/s over the bar crest. For comparison to measured spectra, synthetic spectra of cross-shore flow were computed using measured nearshore profiles. The synthetic spectra were calculated assuming a white runup spectrum of mode-4 edge waves of unit amplitude, although the results would be essentially the same for standing waves or any edge-wave mode above 2. The structure, in the infragravity band, of these synthetic spectra corresponded reasonably well with the structure of the measured spectra. Total variances of measured cross-shore flow within the infragravity band were nondimensionalized by dividing by total infragravity variances of synthetic spectra. These nondimensional variances were independent of distance offshore and increased with the square of the breaker height. Thus, cross-shore flow due to infragravity waves can be estimated with knowledge of the nearshore profile and incident wave conditions.

scholarly journals On the surface-tension of liquids investigated by the method of jet vibration

1907 ◽  
Vol 80 (535) ◽  
pp. 26-27 ◽  
Keyword(s):  
Surface Tension ◽  
Cross Section ◽  
Wave Length ◽  
Standing Waves ◽  
Exact Determination ◽  
Relative Measurements

1. According to Lord Rayleigh’s theory of jet-vibrations, measurement of the length of the standing waves and the velocity and cross-section of a jet, together with the density of the liquid, affords the necessary constants for the calculation of the surface-tension. Notwithstanding the great fundamental advantages of this method, it has only been used in very few cases, and only for relative measurements of the surface-tension. The explanation hereof is to be found in the great difficulties connected with the adequate exact determination of the wave-length, and cross-section or velocity of the jet. As none of the methods in use for the measurement of these quantities could be taken as satisfactory, the main object of this investigation has been to work out really good methods for them.

scholarly journals EXCITATION OF LOW FREQUENCY TRAPPED WAVES

1978 ◽  
Vol 1 (16) ◽  
pp. 25
Author(s):  
Robert King ◽  
Ronald Smith
Keyword(s):  
Incident Wave ◽  
Standing Waves ◽  
Low Frequency ◽  
Nonlinear Interactions ◽  
Edge Waves ◽  
Constant Depth ◽  
Side Band ◽  
Rectangular Basin ◽  
Trapped Wave ◽  
Narrow Wave

Weak nonlinear interactions in water of non-constant depth between an incident wave, a side-band incident wave and a relatively low frequency trapped wave are shown to lead to the generation of the trapped wave. Three situations are considered in detail: edge waves in a wide rectangular basin, progressive edge waves on a straight beach, and standing waves in a narrow wave tank.

scholarly journals GROIN LENGTH AND THE GENERATION OF EDGE WAVES

1976 ◽  
Vol 1 (15) ◽  
pp. 85 ◽  
Author(s):  
Michael K. Gaughan ◽  
Paul D. Komar
Keyword(s):  
Incident Wave ◽  
Wave Length ◽  
Critical Length ◽  
Beach Erosion ◽  
Rip Currents ◽  
Edge Waves ◽  
Normal Waves ◽  
Wave Basin ◽  
Incident Waves ◽  
Selection Of

A series of wave basin experiments were undertaken to better understand the selection of groin spacings and lengths. Rather than obtaining edge waves with the same period as the normal incident waves, subharmonic edge waves were produced with a period twice that of the incoming waves and a wave length equal to the groin spacing. Rip currents were therefore not formed by the interactions of the synchronous edge waves and normal waves as proposed by Bowen and Inman (1969). Rips were present in the wave basin but their origin is uncertain and they were never strong enough to cause beach erosion. The generation of strong subharmonic edge waves conforms with the work of Guza and Davis (1974) and Guza and Inman (1975). The subharmonic edge waves interacted with the incoming waves to give an alternating sequence of surging and collapsing breakers along the beach. Their effects on the swash were sufficient to erode the beach in some places and cause deposition in other places. Thus major rearrangements of the sand were produced between the groins, but significant erosion did not occur as had been anticipated when the study began. By progressively decreasing the length of the submerged portions of the groins, it was found that the strength (amplitude) of the edge waves decreases. A critical submerged groin length was determined whereby the normally incident wave field could not generate resonant subharmonic edge waves of mode zero with a wavelength equal to the groin spacing. The ratio of this critical length to the spacing of the groins was found in the experiments to be approximately 0.15 to 0.20, and did not vary with the steepness of the normal incident waves.

Effect of Coriolis force on edge waves (I) Investigation of the normal modes

2020 ◽  
Vol 78 (4) ◽  
pp. 229-261
Author(s):  
Robert O. Reid
Keyword(s):  
Coriolis Force ◽  
Wind Stress ◽  
Formal Solution ◽  
Wave Length ◽  
Normal Modes ◽  
Low Frequency ◽  
Phase Speed ◽  
Free Edge ◽  
Edge Wave ◽  
Edge Waves

Essentially two classes of free edge waves can exist on a sloping continental shelf in the presence of Coriolis force. For small longshore wave length, fundamental waves of the first class behave like Stokes edge waves. However, for great wave lengths (of several hundred kilometers or more) the characteristics of the first class are significantly altered. In the northern hemisphere the phase speed for waves moving to the right (facing shore from the sea) exceeds the speed for waves which move to the left. Also, the group velocity for a given edge wave mode has a finite upper limit. Waves of the second class are essentially quasigeostrophic boundary waves with very low frequency and, like Kelvin waves, move only to the left (again facing shore from the sea). Unlike Stokes edge waves, those of the quasigeostrophic class are associated with large vorticity. Examination of the formal solution for forced edge waves indicates that those of the second class may be excited significantly by a wind stress vortex. Also, in contrast to the conclusion of Greenspan (1956), it is proposed that a hurricane can effectively excite the higher order edge wave modes in addition to the fundamental if wind stress is considered.

JCPDS-lnternational Centre for Diffraction Data Low-Angle Powder Diffraction Study of Silver Behenate

1994 ◽  
Vol 38 ◽  
pp. 99-105
Author(s):  
T. Blanton ◽  
T. Huang ◽  
H. Toraya ◽  
C. Hubbard ◽  
S. Robie ◽  
...  
Keyword(s):  
Data Analysis ◽  
Data Collection ◽  
Diffraction Data ◽  
Calculation Method ◽  
Full Range ◽  
Internal Standard ◽  
Average Crystallite Size ◽  
Long Period ◽  
Diffraction Peaks ◽  
Characterization Of Materials

Abstract As a result of interest in the characterization of materials with large d-spacings and layer periodicities, it has become necessary to develop a low-angle diffraction material which has welldefined diffraction peaks down to very small 2θ angles. The use of silver behenate, CH3(CH2)20COO-Ag, was introduced by one of the authors (TB) at the 1991 International Centre for Diffraction Data (ICDD) Annual Meeting and was shown to have a set of well-defined (001) diffraction peaks down to 1.5° 2θ when using CuKα radiation. The silver behenate diffraction peaks were observed to be slightly asymmetric with relatively long tails at the low angle side of the peaks. The average crystallite size along the c-axis was estimated using the Scherrer equation and was found to be 900 Å. A task group of the JCPDS-ICJDD Data Collection and Analysis Subcommittee was established with the charge of investigating the use of silver behenate as a possible low-angle calibration material for diffraction applications. Utilizing several data collection and data analysis techniques, d001 long-period spacings in the range of 58.219-58.480 Å were obtained. Using the same collected data and one data analysis refinement calculation method resulted in long-period spacing with a range of 58.303-58.425 Å. Data collected using a silicon internal standard and the same singular data analysis calculation method provided d001 values with a range of 58.363-58.381 Å. The formation of a full-range 2θ diffraction sample was also investigated. Silver behenate and inorganic powders were mixed with an epoxy binder to form a permanent sample which provides diffraction peaks over the entire 2θ range of a powder diffractometer.

Field Observations of Edge Waves

Nature ◽  
1973 ◽  
Vol 243 (5403) ◽  
pp. 160-162 ◽  
Author(s):  
D. A. HUNTLEY ◽  
A. J. BOWEN
Keyword(s):  
Field Observations ◽  
Edge Waves
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