scholarly journals RUN-UP DUE TO BREAKING AND NON-BREAKING WAVES

1974 ◽  
Vol 1 (14) ◽  
pp. 113
Author(s):  
F. Raichlen ◽  
J.L. Hammack
Keyword(s):  
Water Level ◽  
Incident Wave ◽  
Wave Length ◽  
Breaking Waves ◽  
Relative Depth ◽  
Order Unity ◽  
A Value ◽  
Wave Parameters ◽  
Linear Effects ◽  
Run Up

This study was conducted to Investigate the effect of incident wave parameters on run-up for both a smooth-faced structure and a structure armored with quarry-stone. The ratio of the depth-to-wave length (the relative depth) was found to be important in defining wave run-up for both cases. The relative run-up (expressed as the ratio of the run-up elevation above still water level to the incident wave height) for waves which break at the toe of the structure was less than the maximum relative run-up for non-breaking waves for the same relative depth. For both structures, the maximum relative run-up for experiments with long waves occurred at a value of the modified Ursell number, (1/2IT) (HL2/h3) , of order unity which indicates that the nonlinear and linear effects are approximately equal in the incident wave.

scholarly journals A SIMILARITY PARAMETER FOR BREAKWATERS: THE MODIFIED IRIBARREN NUMBER

2018 ◽  
pp. 28
Author(s):  
Maria Clavero ◽  
Pedro Folgueras ◽  
Pilar Diaz-Carrasco ◽  
Miguel Ortega-Sanchez ◽  
Miguel A. Losada
Keyword(s):  
Incident Wave ◽  
Wave Length ◽  
Slope Angle ◽  
Wave Pattern ◽  
Relative Width ◽  
Scattering Parameter ◽  
Wave Regime ◽  
Similarity Parameter ◽  
Mean Water Level ◽  
Run Up

In the 14th ICCE, Battjes (1974) showed that a single similarity parameter only, embodying both the effects of slope angle and incident wave steepness, was important for many aspects of waves breaking on impermeable slopes, and suggested to call it the "Iribarren number", denoted by "Ir". Ahrens and McCartney (1975) verified the usefulness of Ir to describe run-up and stability on rough permeable slopes. Since then, many researchers applied Ir to characterize and to develop formulae for the design of breakwaters and to verify their stability. On the other hand, depending on their typology, breakwaters reflect, dissipate, transmit, and radiate incident wave energy. Partial standing wave patterns are likely to occur at all types of breakwater, thus playing an important role in defining the wave regime in front of, near (seaward and leeward), and inside the breakwater. The characteristics of the porous medium, relative grain size D/L and relative width, Aeq/L2, are relevant magnitudes in that wave pattern (Vilchez et al. 2016), being D the grain diameter, L the wave length and Aeq the porous area per unit section under the mean water level. Aeq/L2 is a scattering parameter controlling the averaged transformation of the wave inside the porous section of the structure. For a vertical porous breakwater (Type A), Aeq is simply B · h, and for a constant depth, the scattering parameter is reduced to B/L, which is the relative breakwater width.

scholarly journals TERRESTRIAL PHOTOGRAMMETRIC MEASUREMENTS OF BREAKING WAVES AND LONGSHORE CURRENTS IN THE NEARSHORE ZONE

1976 ◽  
Vol 1 (15) ◽  
pp. 38 ◽  
Author(s):  
Joseph W. Maresca ◽  
Erwin Seibel
Keyword(s):  
Water Level ◽  
Surf Zone ◽  
Vertical Plane ◽  
Weather Conditions ◽  
Breaking Waves ◽  
Water Levels ◽  
Wind Speeds ◽  
Longshore Currents ◽  
Run Up ◽  
Oblique Images

We conducted a study to determine the feasibility of shore-based, oblique photographic monitoring of breaking waves, water levels, and currents within the surf zone. The purpose of this paper is to describe a new method of oblique single-image and stereoscopic-image analysis, the potential errors, and the types of measurements that can be made in the surf zone. Examples of application are presented to demonstrate the technique. Sophisticated photographic equipment is not required to collect, analyze, and interpret the data. The analysis and error discussions are directed toward the problems encountered using common equipment. Vertical images from aircraft, helicopters, and balloons have been used in the past to study shoreline changes, directional ocean-wave spectra,8 and longshore currents.3 Oblique images taken from the bridge of a ship have been successfully used to measure whitecap coverage under different wind speeds.4 Terrestrial oblique images have been used to study longshore currents,5 ice-ridge formation and breakup,6'7 and beach changes .8 Oblique images, taken with a 35-mm single-lens reflex camera from an elevated point such as a bluff, are particularly suitable for the measurement of breaking waves, water level, beach run-up, and current in the surf zone under storm conditions. In contrast to other techniques of monitoring the surf zone, the photographic technique described in this paper is simple to install, reliable, accurate, and inexpensive. It can be used in all weather conditions, and the analysis of the images is simple. Both stereoscopic and single oblique images can be analyzed, depending on the specific needs and existing environmental conditions. Since the scale of an oblique photograph changes with increasing distance from the camera, the technique is limited in range to about 250 m for a cliff approximately 8 m above the mean water level. Accuracies to within 1% in the horizontal plane and better than 10% in the vertical plane are achievable at this distance.

scholarly journals Probabilistic characteristics of narrow-band long wave run-up onshore

2019 ◽  
Author(s):  
Sergey Gurbatov ◽  
Efim Pelinovsky
Keyword(s):  
Incident Wave ◽  
Narrow Band ◽  
Linear Equations ◽  
Breaking Waves ◽  
Wave Characteristics ◽  
Long Wave ◽  
Nonlinear Shallow Water Theory ◽  
Run Up ◽  
Non Gaussian ◽  
Two Stages

Abstract. The run-up of random long wave ensemble (swell, storm surge and tsunami) on the constant-slope beach is studied in the framework of the nonlinear shallow-water theory in the approximation of non-breaking waves. If the incident wave approaches the shore from deepest water, runup characteristics can be found in two stages: at the first stage, linear equations are solved and the wave characteristics at the fixed (undisturbed) shoreline are found, and, at the second stage, the nonlinear dynamics of the moving shoreline is studied by means of the Riemann (nonlinear) transformation of linear solutions. In the paper, detail results are obtained for quasi-harmonic (narrow-band) waves with random amplitude and phase. It is shown that the probabilistic characteristics of the runup extremes can be found from the linear theory, while the same ones of the moving shoreline – from the nonlinear theory. The role of wave breaking due to large-amplitude outliers is discussed, so that it becomes necessary to consider wave ensembles with non-Gaussian statistics within the framework of the analytical theory of non-breaking waves. The basic formulas for calculating the probabilistic characteristics of the moving shoreline and its velocity through the incident wave characteristics are given. They can be used for estimates of the flooding zone characteristics in marine natural hazards.

scholarly journals Probabilistic characteristics of narrow-band long-wave run-up onshore

2019 ◽  
Vol 19 (9) ◽  
pp. 1925-1935 ◽  
Author(s):  
Sergey Gurbatov ◽  
Efim Pelinovsky
Keyword(s):  
Incident Wave ◽  
Narrow Band ◽  
Linear Equations ◽  
Breaking Waves ◽  
Wave Characteristics ◽  
Long Wave ◽  
Nonlinear Shallow Water Theory ◽  
Run Up ◽  
Non Gaussian ◽  
Two Stages

Abstract. The run-up of random long-wave ensemble (swell, storm surge, and tsunami) on the constant-slope beach is studied in the framework of the nonlinear shallow-water theory in the approximation of non-breaking waves. If the incident wave approaches the shore from the deepest water, run-up characteristics can be found in two stages: in the first stage, linear equations are solved and the wave characteristics at the fixed (undisturbed) shoreline are found, and in the second stage the nonlinear dynamics of the moving shoreline is studied by means of the Riemann (nonlinear) transformation of linear solutions. In this paper, detailed results are obtained for quasi-harmonic (narrow-band) waves with random amplitude and phase. It is shown that the probabilistic characteristics of the run-up extremes can be found from the linear theory, while the same ones of the moving shoreline are from the nonlinear theory. The role of wave-breaking due to large-amplitude outliers is discussed, so that it becomes necessary to consider wave ensembles with non-Gaussian statistics within the framework of the analytical theory of non-breaking waves. The basic formulas for calculating the probabilistic characteristics of the moving shoreline and its velocity through the incident wave characteristics are given. They can be used for estimates of the flooding zone characteristics in marine natural hazards.

scholarly journals CFD Investigations of 2D Greenwater Overtopping of a Floating Offshore Vessel

2019 ◽  
Author(s):  
Xiantao Zhang ◽  
Scott Draper ◽  
Hugh Wolgamot ◽  
Wenhua Zhao ◽  
Lifen Chen ◽  
...  
Keyword(s):  
Incident Wave ◽  
Momentum Flux ◽  
Cfd Simulation ◽  
Wave Length ◽  
Linear Potential ◽  
Wave Groups ◽  
A Value ◽  
Wave Elevation ◽  
Horizontal Momentum ◽  
Incident Waves

Abstract In this paper, 2D greenwater overtopping of a floating box is numerically investigated using CFD. The incident waves used are compact wave groups which correspond to the maximum relative wave elevation at the edge of the box according to linear theory. The motion of the box for which only heave and pitch modes are considered is calculated using linear potential flow theory and then prescribed in the CFD simulation. It is found that the normalized maximum horizontal momentum flux of greenwater overtopped onto the moving box is consistent with that for a fixed box when the incident wave length is much smaller than the box length. For longer incident wave lengths there is arguably more scatter in the momentum flux compared with that of a fixed box, although the result is still bounded by a value of 1.5 times that predicted by a classical dam break solution. This additional scatter is shown to be due to the effect of box motion.

Preliminary observations on escape swimming and giant neurons in Aglantha digitale (Hydromedusae: Trachylina)

1980 ◽  
Vol 58 (4) ◽  
pp. 549-552 ◽  
Author(s):  
S. Donaldson ◽  
G. O. Mackie ◽  
A. Roberts
Keyword(s):  
Action Potentials ◽  
Giant Axon ◽  
Synaptic Delay ◽  
Giant Axons ◽  
A Value ◽  
Giant Synapses ◽  
Run Up

Aglantha can swim in two ways, one of which, fast swimming, is evoked by contact with predators and serves for escape. The response consists of two or three violent contractions of which the first propels the animal a distance equivalent to five body lengths. Peak velocities in the range 0.3–0.4 m s−1 were measured. Drag is reduced by contraction of the tentacles.Coordination of escape swimming and tentacle contraction is achieved by a system of giant axons. A giant axon runs down each tentacle; action potentials in these elements show a one-for-one correspondence with potentials recorded from a ring-shaped axon lying in the margin near the tentacle bases. The ring giant synapses with eight motor giants which run up the subumbrella innervating the swimming muscles.Conduction velocities in the giant axons may be as high as 4.0 m s−1 in the case of the largest (40 μm diameter) axons. A value of 1.6 ms was obtained for minimum synaptic delay between the ring and motor giant axons.

Caudal Fin and Body Movement in the Propulsion of some Fish

1963 ◽  
Vol 40 (1) ◽  
pp. 23-56 ◽  
Author(s):  
RICHARD BAINBRIDGE
Keyword(s):  
Body Movement ◽  
Wave Length ◽  
The Body ◽  
Whole Body ◽  
Tail Region ◽  
Caudal Fin ◽  
A Value ◽  
Total Thrust ◽  
Transverse Movement ◽  
Relationship Of

1. Observations made on bream, goldfish and dace swimming in the ‘Fish Wheel’ apparatus are described. These include: 2. An account of the complex changes in curvature of the caudal fin during different phases of the normal locomotory cycle. Measurements of this curvature and of the angles of attack associated with it are given. 3. An account of changes in area of the caudal fin during the cycle of lateral oscillation. Detailed measurements of these changes, which may involve a 30 % increase in height or a 20 % increase in area, are given. 4. An account of the varying speed of transverse movement of the caudal fin under various conditions and the relationship of this to the changes in area and amount of bending. Details of the way this transverse speed may be asymmetrically distributed relative to the axis of progression of the fish are given. 5. An account of the extent of the lateral propulsive movements in other parts of the body. These are markedly different in the different species studied. Measurements of the wave length of this movement and of the rate of progression of the wave down the body are given. 6. It is concluded that the fish has active control over the speed, the amount of bending and the area of the caudal fin during transverse movement. 7. The bending of the fin and its changes in area are considered to be directed to the end of smoothing out and making more uniform what would otherwise be an intermittent thrust from the oscillating tail region. 8. Some assessment is made of the proportion of the total thrust contributed by the caudal fin. This is found to vary considerably, according to the form of the lateral propulsive movements of the whole body, from a value of 45% for the bream to 84% for the dace.

A Coupled-Mode Technique for the Run-Up of Non-Breaking Dispersive Waves on Plane Beaches

2006 ◽  
Author(s):  
K. A. Belibassakis ◽  
G. A. Athanassoulis
Keyword(s):  
Shallow Water ◽  
Water Waves ◽  
Wave Equations ◽  
Neumann Boundary ◽  
Breaking Waves ◽  
Numerical Results ◽  
Coupled Mode Theory ◽  
Mode Theory ◽  
Coupled Mode ◽  
Run Up

A coupled-mode model is developed and applied to the transformation and run-up of dispersive water waves on plane beaches. The present work is based on the consistent coupled-mode theory for the propagation of water waves in variable bathymetry regions, developed by Athanassoulis & Belibassakis (1999) and extended to 3D by Belibassakis et al (2001), which is suitably modified to apply to a uniform plane beach. The key feature of the coupled-mode theory is a complete modal-type expansion of the wave potential, containing both propagating and evanescent modes, being able to consistently satisfy the Neumann boundary condition on the sloping bottom. Thus, the present approach extends previous works based on the modified mild-slope equation in conjunction with analytical solution of the linearised shallow water equations, see, e.g., Massel & Pelinovsky (2001). Numerical results concerning non-breaking waves on plane beaches are presented and compared with exact analytical solutions; see, e.g., Wehausen & Laitone (1960, Sec. 18). Also, numerical results are presented concerning the run-up of non-breaking solitary waves on plane beaches and compared with the ones obtained by the solution of the shallow-water wave equations, Synolakis (1987), Li & Raichlen (2002), and experimental data, Synolakis (1987).

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.

scholarly journals NON-BREAKING AND BREAKING WAVE LOADS ON A COOLING WATER OUTFALL

1978 ◽  
Vol 1 (16) ◽  
pp. 148
Author(s):  
G.R. Mogridge ◽  
W.W. Jamieson
Keyword(s):  
Water Level ◽  
Cooling Water ◽  
High Water ◽  
Breaking Waves ◽  
Irregular Waves ◽  
Scale Model ◽  
Breaking Wave ◽  
Wave Loads ◽  
Eastern Canada ◽  
Spilling Breakers

Cooling water from a power generating station in Eastern Canada is pumped to an outfall and distributed into the ocean through discharge ports in the sidewalls of a diffuser cap. The cap is essentially a shell-type structure consisting of a submerged circular cylinder 26.5 ft in diameter and 14 ft high. It is located in 25 ft of water at low water level and 54 ft at high water level. Horizontal forces, vertical forces and overturning moments exerted by waves on a 1:36 scale model of the diffuser cap were measured with and without cooling water discharging from the outfall. Tests were run with regular and irregular waves producing both non-breaking and breaking wave loads on the diffuser cap. The overturning moments measured on the diffuser cap were up to 150 percent greater than those on a solid submerged cylinder sealed to the seabed. Unlike sealed cylinders, all of the wave loads measured on the relatively open structure reached maximum values at approximately the same time. The largest wave loads were measured on the diffuser structure when it was subjected to spilling breakers at low water level. For a given wave height, the spilling breakers caused wave loads up to 100 percent greater than those due to non-breaking waves.

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