scholarly journals EDGE WAVES AND THE LITTORAL ENVIRONMENT

1972 ◽  
Vol 1 (13) ◽  
pp. 67 ◽  
Author(s):  
Anthony J. Bowen
Keyword(s):  
Surface Waves ◽  
Broad Spectrum ◽  
Surf Zone ◽  
Wave Mode ◽  
Dominant Mode ◽  
Edge Wave ◽  
Wave Spectra ◽  
Edge Waves ◽  
Wave Processes ◽  
Induced Changes

Several types of beach features seem to have a rather regular, longshore pattern. This pattern may indeed he sufficiently uniform to be described in terms of a recognisable longshore wavelength. A likely explanation for such features lies in the motion of edge waves, surface waves trapped by refraction to the shoreline. These waves, by themselves or by interaction with the normal, incoming surface waves breaking on the beach, can generate longshore features having a wavelength equal to or half the edge wave wavelength. If a broad spectrum of edge wave modes were present any longshore variation should appear rather irregular. The existence of regular features therefore suggests that a particular edge wave mode is often dominant, the characteristics of the dominant mode depending on the geometry of the nearshore area and the width of the surf zone. Any new, artificial structure stretching seawards provides new boundary conditions, almost certainly altering the characteristic of the edge wave spectra. This is particularly obvious in the case of a regularly spaced structure such as a s'et of groynes. A deeper understanding of the edge wave processes is needed so that the induced changes in the edge wave spectra are the least deleterious or, an intriguing possibility, advantageous.

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.

On the radiation damping of finite-amplitude progressive edge waves

1990 ◽  
Vol 431 (1883) ◽  
pp. 419-431 ◽  
Keyword(s):  
Wave Theory ◽  
Wave Dispersion ◽  
Wave Mode ◽  
Finite Amplitude ◽  
Edge Wave ◽  
Water Model ◽  
Edge Waves ◽  
Transfer Energy ◽  
Oblique Waves ◽  
Weakly Nonlinear

Using small-amplitude expansions, it is demonstrated that weakly nonlinear periodic edge waves, travelling along the shoreline of a beach, can be attenuated owing to radiation of oblique waves out to sea. A few beach profiles, for which edge-wave dispersion relations are known in closed form, are discussed, and necessary conditions are determined for such radiation to occur due to nonlinear self-interactions. In particular, it is shown that quadratic nonlinear interactions cause the second edge-wave mode on a uniformly sloping beach of slope α to radiate when 1/18π < α < ⅙π; a detailed derivation to find the amplitude of the radiated wave and the attendant decay rate of the edge wave is presented, using the full water-wave theory. Also, it is pointed out that a concomitant nonlinear mechanism can transfer energy from incoming oblique waves to subharmonic edge waves – a plausible mechanism for the generation of travelling edge waves in coastal waters – and the details of this process are discussed within the framework of a shallow-water model.

scholarly journals Development and Validation of Quasi-Eulerian Mean Three-Dimensional Equations of Motion Using the Generalized Lagrangian Mean Method

2021 ◽  
Vol 9 (1) ◽  
pp. 76
Author(s):  
Duoc Nguyen ◽  
Niels Jacobsen ◽  
Dano Roelvink
Keyword(s):  
Surface Waves ◽  
Deep Water ◽  
Surf Zone ◽  
Equations Of Motion ◽  
Three Dimensional ◽  
Breaking Waves ◽  
Successful Implementation ◽  
Random Waves ◽  
Mean Motion ◽  
Generalized Lagrangian

This study aims at developing a new set of equations of mean motion in the presence of surface waves, which is practically applicable from deep water to the coastal zone, estuaries, and outflow areas. The generalized Lagrangian mean (GLM) method is employed to derive a set of quasi-Eulerian mean three-dimensional equations of motion, where effects of the waves are included through source terms. The obtained equations are expressed to the second-order of wave amplitude. Whereas the classical Eulerian-mean equations of motion are only applicable below the wave trough, the new equations are valid until the mean water surface even in the presence of finite-amplitude surface waves. A two-dimensional numerical model (2DV model) is developed to validate the new set of equations of motion. The 2DV model passes the test of steady monochromatic waves propagating over a slope without dissipation (adiabatic condition). This is a primary test for equations of mean motion with a known analytical solution. In addition to this, experimental data for the interaction between random waves and a mean current in both non-breaking and breaking waves are employed to validate the 2DV model. As shown by this successful implementation and validation, the implementation of these equations in any 3D model code is straightforward and may be expected to provide consistent results from deep water to the surf zone, under both weak and strong ambient currents.

The fundamental ultrasonic edge wave mode: Propagation characteristics and potential for distant damage detection

Ultrasonics ◽  
2021 ◽  
Vol 114 ◽  
pp. 106369
Author(s):  
James M. Hughes ◽  
Munawwar Mohabuth ◽  
Andrei Kotousov ◽  
Ching-Tai Ng
Keyword(s):  
Damage Detection ◽  
Wave Mode ◽  
Edge Wave ◽  
Mode Propagation ◽  
Propagation Characteristics

Scattering of the Fundamental Symmetric Wave Mode Incident at a Defect on the Blind Side of a Weep Hole in an Isotropic Plate

2014 ◽  
Vol 891-892 ◽  
pp. 1237-1242 ◽  
Author(s):  
Benjamin Steven Vien ◽  
Nithurshan Nadarajah ◽  
Wing Kong Chiu ◽  
L.R. Francis Rose
Keyword(s):  
Isotropic Plate ◽  
Wave Mode ◽  
Blind Side ◽  
Edge Waves ◽  
Computational Simulations ◽  
Metallic Structures ◽  
Element Simulation ◽  
Symmetric Wave ◽  
Open Hole ◽  
Non Destructive

The scattering of a fundamental symmetric wave mode by a notch on the blind side of weep hole is described in this paper. It will report on findings obtained from computational simulations to determine the effect and interaction of the impinging waves with the defect on the open hole located on the blind side of the incident wave. The finite element simulation results showed mode conversions of fundamental modes, leaky edge waves on the circumferential surface and source-like diffractions radiating from the tip of the notch and hole. These findings highlight the potential of applying this wave phenomenon to quantify defect located hard-to-inspect areas by positioning actuator and sensor in accessible regions of metallic structures and is relevant to the development and improvement of current techniques in non-destructive inspection of metallic structures

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.

Surface waves in basins of variable depth

1985 ◽  
Vol 152 ◽  
pp. 379-389 ◽  
Author(s):  
John Miles
Keyword(s):  
Differential Equation ◽  
Partial Differential Equation ◽  
Surface Waves ◽  
Rayleigh Quotient ◽  
Dominant Mode ◽  
Variable Depth ◽  
Partial Differential ◽  
Variational Approximations ◽  
Inverse Results ◽  
Variational Form

The linearized boundary-value problem for surface waves of frequency ω in a closed basin of variable depth is reduced to a non-self-adjoint partial differential equation in the plane of the free surface. The corresponding variational form (which does not provide a definite upper or lower bound) for the eigenvalue κ = ω2/g is constructed. A self-adjoint partial differential equation, for which the variational form is the Rayleigh quotient (which provides an upper bound to κ), also is constructed; it offers significant advantages vis-à-vis the non-self-adjoint formulation, but at the expense of a more complicated operator. Three relatively simple variational approximations are constructed, two for a class of basins with sloping sides and the third for basins for which the variation of the depth relative to its mean is small. These general results are illustrated by comparison with Rayleigh's (1899) results for a semicircular channel, Sen's (1927) inverse results for a family of circular basins, and Lamb's (1932) results for a shallow circular paraboloid. The eigenvalue for the dominant mode in the paraboloid is determined through O(δ5), where δ = depth/radius.

The generation of surface waves over a sloping beach by an oscillating line source

1976 ◽  
Vol 79 (3) ◽  
pp. 573-585 ◽  
Author(s):  
Clare A. N. Morris
Keyword(s):  
Free Surface ◽  
Surface Waves ◽  
Line Source ◽  
Short Wave ◽  
Long Waves ◽  
Edge Waves ◽  
Wave Regime ◽  
Wave Solutions ◽  
Sloping Beach

AbstractA line source whose strength varies sinusoidally with time and also with the co-ordinate measured along its length is situated parallel to the shoreline of a beach of angle ¼π0. Both long-and short-wave solutions are found. It is shown that for certain positions of the source, long waves are not radiated to infinity, while in the short-wave regime, the solutions take the form of edge-waves, with resonances occurring at certain wavenumbers. Computations of the free-surface contours are presented for a range of wavenumbers.

scholarly journals The broad spectrum mixed-lineage kinase 3 inhibitor URMC-099 prevents acute microgliosis and cognitive decline in a mouse model of perioperative neurocognitive disorders

2019 ◽  
Author(s):  
Patrick Miller-Rhodes ◽  
Cuicui Kong ◽  
Gurpreet S. Baht ◽  
Ramona M. Rodriguiz ◽  
William C. Wetsel ◽  
...  
Keyword(s):  
Broad Spectrum ◽  
Orthopedic Surgery ◽  
Therapeutic Option ◽  
Postoperative Cognitive Dysfunction ◽  
Light Sheet ◽  
Neurocognitive Disorders ◽  
Mixed Lineage Kinase ◽  
Light Sheet Microscopy ◽  
Mixed Lineage Kinase 3 ◽  
Induced Changes

AbstractPerioperative neurocognitive disorders (PND), including delirium and postoperative cognitive dysfunction, are serious complications that afflict up to 50% of surgical patients and for which there are no disease-modifying therapeutic options. Here, we test whether prophylactic treatment with the broad spectrum mixed-lineage kinase 3 inhibitor URMC-099 prevents surgery-induced neuroinflammation and cognitive impairment in a translational model of orthopedic surgery-induced PND. We used a combination of two-photon scanning laser microscopy and CLARITY with light-sheet microscopy to define surgery-induced changes in microglial dynamics and morphology. Orthopedic surgery induced widespread microglial activation in the hippocampus and cortex that accompanied impairments in episodic memory. URMC-099 prophylaxis prevented these neuropathological sequelae without impacting bone fracture healing. Together, these findings provide compelling evidence for the advancement of URMC-099 as a therapeutic option for PND.

scholarly journals VARIABILITY OF LONGSHORE CURRENTS

1978 ◽  
Vol 1 (16) ◽  
pp. 43
Author(s):  
R.T. Guza ◽  
E.B. Thornton
Keyword(s):  
Gravity Waves ◽  
Direct Relationship ◽  
Surf Zone ◽  
Rip Currents ◽  
Spatial Averaging ◽  
Edge Waves ◽  
Radiation Stress ◽  
Simultaneous Measurements ◽  
Longshore Currents ◽  
Temporal And Spatial

Simultaneous measurements were made of the offshore directional spectra of gravity waves, and longshore currents within the surf zone. The goal was to test theories which suggest a direct relationship between mean longshore currents (V) in the surf zone and offshore values of the off axis component of radiation stress (S ). Seventeen minute — xv averages of both S and V showed considerable temporal xv variation, and little or no tendency to vary together. There was also considerable longshore spatial variability of the 1ongshore"current. Attempts to measure gradients of S in the surf zone failed because of small errors in instrument orientation. The measurements suggest that considerable temporal and spatial averaging will generally be required to obtain a representative picture of longshore currents, even if no rip currents are present, due to the presence of "eddy" motions or long edge waves.

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