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 SURF SIMILARITY

1974 ◽  
Vol 1 (14) ◽  
pp. 26 ◽  
Author(s):  
J.A. Battjes
Keyword(s):  
Phase Difference ◽  
Incident Wave ◽  
Water Waves ◽  
Slope Angle ◽  
Wave Steepness ◽  
Similarity Parameter ◽  
General Terms ◽  
Depth Ratio ◽  
Run Up ◽  
Set Up

This paper deals with the following aspects of periodic water waves breaking on a plane slope breaking criterion, breaker type, phase difference across the surfzone, breaker height-to-depth ratio, run-up and set-up, and reflection. It is shown that these are approximately governed by a single similarity parameter only, embodying both the effects of slope angle and incident wave steepness. Various physical interpretations of this similarity parameter are given, while its role is discussed m general terms from the viewpoint of model prototype similarity.

scholarly journals CHARACTERISTICS OF FLOW IN RUN-UP OF PERIODIC WAVES

1976 ◽  
Vol 1 (15) ◽  
pp. 44 ◽  
Author(s):  
Ary Roos ◽  
Jurjen A. Battjes
Keyword(s):  
Slope Angle ◽  
Water Layer ◽  
Periodic Waves ◽  
Wave Steepness ◽  
Slope Gradient ◽  
Characteristic Parameters ◽  
Similarity Parameter ◽  
The Mean ◽  
Run Up ◽  
Particle Velocities

An experimental study is presented of some characteristic parameters of the flow in the up-rush and down-rush of periodic waves breaking on a plane, smooth slope. The water layer thickness has been measured as a function of time at four locations above still water level. Discharges and particle velocities have been calculated. The results have been made nondimensional on the basis of Hunt's formula for the run-up height. They appear to be either independent of the wave steepness H/L and slope gradient tan Ct or to be a function of a single similarity parameter £ - tana / yH/L only. An hypothesis is stated concerning a relation between the mean rate of overtopping of a dike by waves, and the run-up which would occur under the same circumstances on an uninterrupted slope. On the basis of this hypothesis the overtopping volume per wave can be normalized so as to make it independent of slope angle and wave steepness. A comparison of the result with measurements from other sources indicates a rough agreement.

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.

Hydrodynamic characteristics of vertical and quadrant face pile supported breakwater under oblique waves

2021 ◽  
pp. 147509022110313
Author(s):  
T J Jemi Jeya ◽  
V Sriram ◽  
V Sundar
Keyword(s):  
Experimental Study ◽  
Hydrodynamic Performance ◽  
Hydrodynamic Characteristics ◽  
Scattering Parameter ◽  
Oblique Waves ◽  
Test Conditions ◽  
Relative Water ◽  
Identical Test ◽  
Run Up ◽  
Water Depths

This paper presents the results from a comprehensive experimental study on the Quadrant Face Pile Supported Breakwater (QPSB) in two different water depths exposed to three different oblique wave attacks. The results are compared with that for a Vertical face Pile Supported Breakwater (VPSB) for identical test conditions. The paper compares the reflection coefficient, transmission coefficient, energy loss coefficient, non-dimensional pressure, and non-dimensional run-up as a function of the relative water depth and scattering parameter. The results obtained for QPSB are validated with existing results. The salient observations show that QPSB experiences better hydrodynamic performance characteristics than the VPSB under oblique waves.

Wave-Vessel Interactions in Beam Seas

2009 ◽  
Author(s):  
Eirini Spentza ◽  
Chris Swan
Keyword(s):  
Wave Field ◽  
Incident Wave ◽  
Laboratory Data ◽  
Wave Structure ◽  
Wave Pattern ◽  
Scaled Model ◽  
Beam Seas ◽  
Wave Basin ◽  
Wave Slamming ◽  
Speed Of Propagation

This paper concerns the nonlinear interaction of waves with a floating vessel. A detailed experimental study has been undertaken in a 3-D wave basin, using a scaled model tanker subject to a variety of incident wave conditions. The vessel, which is free to move in heave, pitch and roll, has a draft of 14m (at full-scale) and is subject to a range of incident wave periods propagating at right angles to the side shell of the vessel. Measurements undertaken with and without the vessel in place allow the diffracted-radiated wave field to be identified. The laboratory data indicate that the diffracted-radiated wave pattern varies significantly with the incident wave period. Detailed analysis of the experimental results has identified a hitherto unexpected second-order freely propagating wave harmonic generated due to the presence of the vessel. Given its frequency content and its relatively slow speed of propagation, this harmonic leads to a significant steepening of the wave field around the vessel and therefore has an important role to play in terms of the occurrence of wave slamming. Physical insights are provided concerning the latter and the practical implications of the overall wave-structure interactions are considered.

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.

Wave Steepness and Relative Width: Influence on Transmission Coefficient of Horizontal Interlaced, Multilayered, Moored Floating Pipe Breakwater With Five Layers

2011 ◽  
Vol 45 (5) ◽  
pp. 20-27
Author(s):  
Sacchi Rajappa ◽  
Arkal Vittal Hegde ◽  
Subba Rao ◽  
Veena Channegowda
Keyword(s):  
Physical Model ◽  
Transmission Coefficient ◽  
Wave Height ◽  
Incident Wave ◽  
Wave Attenuation ◽  
Transmitted Wave ◽  
Relative Width ◽  
Wave Steepness ◽  
Transmission Characteristics ◽  
Time Period

AbstractThis paper presents the results of a series of physical model scale experiments conducted to determine the transmission characteristics of a horizontal interlaced, multilayered, moored floating pipe breakwater. The studies are conducted on physical breakwater models having five layers of PVC pipes. The wave steepness (Hi/gT2, where Hi is incident wave height, g is acceleration due to gravity, and T is time period) was varied between 0.063 and 0.849, relative width (W/L, where W is width of breakwater and L is the wavelength) was varied between 0.4 and 2.65, and relative spacing (S/D, where S is horizontal centre to centre spacing of pipes and D is the diameter of pipes) was set equal to 2. The transmitted wave height is measured, and the gathered data are analyzed by plotting nondimensional graphs depicting the variation of Kt (transmission coefficient) with Hi/gT2 for values of d/W (d is depth of water) and of Kt with W/L for values of Hi/d. It is observed that Kt decreases as Hi/gT2 increases for the range of d/W between 0.082 and 0.139. It is also observed that Kt decreases with an increase in W/L values for the range of Hi/d from 0.06 to 0.40. The maximum wave attenuation achieved with the present breakwater configuration is 78%.

Wave Induced Pressures on Pipelines Near a Sloping Boundary Due to Regular Waves

2002 ◽  
Author(s):  
K. A. Roopsekhar ◽  
V. Sundar
Keyword(s):  
Time History ◽  
Wave Direction ◽  
Regular Waves ◽  
Scattering Parameter ◽  
Similarity Parameter ◽  
Experimental Procedure ◽  
Sloping Bed ◽  
Model Setup ◽  
Force Time ◽  
Wave Induced

The hydrodynamic pressures due to regular waves around the circumference of a pipeline near a sloping rigid bed and placed parallel to the wave direction have been measured. The pressures were integrated to obtain the force time history, from which the peak horizontal and vertical forces were evaluated. The effects of relative clearance of pipe from the bed and its relative position from the toe of the sloping bed on the pressures and forces on the pipeline as a function scattering parameter and wave steepness are reported. The reflection characteristics of the sloping bed in the presence of the pipeline are reported as a function of surf similarity parameter and compared with the results from existing literature. The details of the model setup, experimental procedure, results and discussion are presented in this paper.

Results of Double-Theodolite Observations at Bishop, Cal., in Connection with the “Bishop-Wave” Phenomena *

1952 ◽  
Vol 33 (3) ◽  
pp. 107-116 ◽  
Author(s):  
DeVer Colson
Keyword(s):  
Wave Length ◽  
Wave Pattern ◽  
Entire Period ◽  
Pilot Balloon ◽  
Observation Program ◽  
Local Topography ◽  
Horizontal Wave ◽  
The Mean ◽  
Upper Level ◽  
Wave Phenomena

A double-theodolite pilot-balloon observation program was inaugurated at the Bishop, California, Weather Bureau station in order to obtain data on the actual air currents in that area. The results of the observations for the period from February through May 1951 are discussed. Comparisons between single- and double-theodolite computations are shown. The mean actual ascension rates are compared for each month, and the mean ascension rates for the entire period are compared with the standard assumed single-thodolite ascension rates. Relations between the mean actual ascension rates and the local topography, the elevation of the balloon, the direction and speed of the general upper-level wind are shown. Several examples are given showing the existence of the standing (“Bishop” or “Sierra”)-wave pattern in the double-theodolite data. In some cases, the location of the up and downdrafts as well as the horizontal wave length can be determined.

Steady wave patterns on a non-uniform steady fluid flow

1960 ◽  
Vol 9 (3) ◽  
pp. 333-346 ◽  
Author(s):  
F. Ursell
Keyword(s):  
Wave Length ◽  
Present Theory ◽  
Wave Pattern ◽  
Wave Crest ◽  
Stream Velocity ◽  
List Type ◽  
Mathematical Form ◽  
Local Wave ◽  
Pass Through ◽  
The Waves

A steady slightly non-uniform flow with a free surface is subject to a concentrated surface pressure which gives rise to a pattern of surface waves. (For gravity waves on deep water this is the well-known Kelvin ship-wave pattern.) The motion is assumed inviscid, and the waves are assumed small. A theory is developed for the wave pattern, based on the following assumptions: The stream velocity component normal to a wave crest is equal to the phase velocity based on the local wavelength;the separation between consecutive crests is equal to the local wave-length. These assumptions are expressed in mathematical form, and the existence of a set of characteristic curves (associated with the group velocity) is deduced from them. These characteristics are not identical with the crests. Let the additional assumption be made thatthe characteristics all pass through the point disturbance; the characteristics are then completely defined and may be constructed by a step-by-step process starting at the point disturbance. The same construction gives the direction of the wave crests at all points. The wave crests can then be deduced.Assumptions of the same type as (1) and (2) have long been familiar in various applications of ray tracing. For uniform flows the present theory gives the same pattern as the method of stationary phase.

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