scholarly journals THE INTERACTION OF WAVES AND CURRENTS OVER A LONGSHORE BAR

1986 ◽  
Vol 1 (20) ◽  
pp. 116 ◽  
Author(s):  
I.A. Svendsen ◽  
J. Buhr Hansen
Keyword(s):  
Wave Height ◽  
Wave Motion ◽  
Surf Zone ◽  
Wave Theory ◽  
Runge Kutta Method ◽  
Waves And Currents ◽  
Set Up ◽  
The Waves ◽  
Wave Properties ◽  
A Current

A two-dimensional model for waves and steady currents in the surf zone is developed. It is based on a depth integrated and time averaged version of the equations for the conservation of mass, momentum, and wave energy. A numerical solution is described based on a fourth order Runge-Kutta method. The solution yields the variation of wave height, set-up, and current in the surf zone, taking into account the mass flux in the waves. In its general form any wave theory can be used for the wave properties. Specific results are given using the description for surf zone waves suggested by Svendsen (1984a), and in this form the model is used for the wave motion with a current on a beach with a longshore bar. Results for wave height and set-up are compared with measurements by Hansen & Svendsen (1986).

scholarly journals WAVE ATTENUATION AND SET-UP ON A BEACH

1984 ◽  
Vol 1 (19) ◽  
pp. 4 ◽  
Author(s):  
I.A. Svendsen
Keyword(s):  
Surf Zone ◽  
Wave Attenuation ◽  
Outer Region ◽  
Dimensional Model ◽  
Radiation Stress ◽  
Wave Heights ◽  
Actual Flow ◽  
Set Up ◽  
The Waves ◽  
Wave Properties

A theoretical two-dimensional model for wave heights and set-up in a surf zone is described and compared to measurements. The integral wave properties energy flux Ef, and radiation stress Sxx are determined from crude approximations of the actual flow in surf zone waves. Some physical aspects of the outer region are discussed and found to agree with our knowledge of the waves seawards and shorewards of this region.

Changes of the mean velocity profiles in the combined wave–current motion described in a GLM formulation

1998 ◽  
Vol 370 ◽  
pp. 271-296 ◽  
Author(s):  
J. GROENEWEG ◽  
G. KLOPMAN
Keyword(s):  
Velocity Profiles ◽  
Perturbation Series ◽  
Wave Crest ◽  
Mean Velocity ◽  
Initial Current ◽  
Eulerian Formulation ◽  
Waves And Currents ◽  
The Mean ◽  
The Waves ◽  
A Current

The generalized Lagrangian mean (GLM) formulation is used to describe the interaction of waves and currents. In contrast to the more conventional Eulerian formulation the GLM description enables splitting of the mean and oscillating motion over the whole depth in an unambiguous and unique way, also in the region between wave crest and trough. The present paper deals with non-breaking long-crested regular waves on a current using the GLM formulation coupled with a WKBJ-type perturbation-series approach. The waves propagate under an arbitrary angle with the current direction. The primary interest concerns nonlinear changes in the vertical distribution of the mean velocity due to the presence of the waves, but modifications of the orbital velocity profiles, due to the presence of a current, are considered as well. The special case of no initial current, where waves induce a so-called drift velocity or mass-transport velocity, is also studied.

scholarly journals HYPERBOLIC WAVES AND THEIR SHOALING

1968 ◽  
Vol 1 (11) ◽  
pp. 9 ◽  
Author(s):  
Yuichi Iwagaki
Keyword(s):  
Wave Height ◽  
Elliptic Functions ◽  
Wave Theory ◽  
Wave Crest ◽  
Cnoidal Wave ◽  
Practical Application ◽  
Jacobian Elliptic Functions ◽  
Complete Elliptic Integrals ◽  
Hyperbolic Waves ◽  
The Waves

Is is very difficult for engineers to deal with the cnoidal wave theory for practical application, since this theory contains the Jacobian elliptic functions, their modulus k, and the complete elliptic integrals of the first and second kinds, K and E respectively. This paper firstly proposes formulae for various wave characteristics of new waves named "hyperbolic waves", which are derived from the cnoidal wave theory under the condition that k = 1 and E = 1 but K is not infinite and are a function of T/g/h and H/h, so that cnoidal waves can be approximately expressed as hyperbolic waves by primary functions only, in which T is the wave period, h the water depth and H the wave height. Secondly, as an application of the hyperbolic wave theory, the present paper deals with wave shoaling, that is, changes in the wave height, the wave crest height above still water level, and the wave velocity, when the waves proceed into shallow water from deep water.

scholarly journals RELIABILITY OF PRESSURE SENSORS TO MEASURE WAVE HEIGHT IN THE SHOALING REGION

2018 ◽  
pp. 10 ◽  
Author(s):  
Massimiliano Marino ◽  
Iván Cáceres Rabionet ◽  
Rosaria Ester Musumeci ◽  
Enrico Foti
Keyword(s):  
Wave Height ◽  
Large Scale ◽  
Surf Zone ◽  
Transfer Functions ◽  
Pressure Sensors ◽  
Experimental Dataset ◽  
Wave Flume ◽  
Intermediate Waters ◽  
The Waves

A comparison between a range of transfer functions to recover wave height from pressure sensors data is presented. The analysis is carried out by means of a large-scale wave flume experimental dataset, in which resistive, acoustic and pressure gauges recovered wave height are compared as the waves travel from intermediate waters, to the shoaling region and finally into the surf zone. All the considered transfer functions result adequate in recovering wave height in intermediate waters, becoming gradually less accurate as the steepness of the wave increases in the shoaling region and in the surf zone. The accuracy of the compared transfer functions is assessed by means of an ensemble wave height based deviation.

scholarly journals WAVE CHARACTERISTICS IN THE SURF ZONE

1978 ◽  
Vol 1 (16) ◽  
pp. 29 ◽  
Author(s):  
I.A. Svendsen ◽  
P.A. Madsen ◽  
J. Buhr Hansen
Keyword(s):  
Free Surface ◽  
Energy Balance ◽  
Wave Height ◽  
Wave Motion ◽  
Surf Zone ◽  
Free Surface Flow ◽  
Surface Flow ◽  
Height Variation ◽  
Wave Characteristics ◽  
Velocity Of Propagation

The equations describing conservation of mass, momentum and energy in a turbulent free surface flow are derived for a controle volume extending over the whole depth. The effect of the turbulent surface oscillations are discussed but neglected in the following analysis, where the equations are applied to the energy balance in a surf zone wave motion. This leads to results for the wave height variation and the velocity of propagation. The results cannot be reconciled completely with measurements and the concluding discussion is aimed at revealing how the model can be improved.

Forced small-amplitude water waves: a comparison of theory and experiment

1960 ◽  
Vol 7 (1) ◽  
pp. 33-52 ◽  
Author(s):  
F. Ursell ◽  
R. G. Dean ◽  
Y. S. Yu
Keyword(s):  
Wave Height ◽  
Water Waves ◽  
Small Amplitude ◽  
Experimental Error ◽  
Wave Motion ◽  
Wave Theory ◽  
Finite Amplitude ◽  
Uniform Density ◽  
Wave Channel ◽  
Wave Heights

This paper describes an attempt to verify experimentally the wavemaker theory for a piston-type wavemaker. The theory is based upon the usual assumptions of classical hydrodynamics, i.e. that the fluid is inviscid, of uniform density, that motion starts from rest, and that non-linear terms are neglected. If the water depth, wavelength, wave period, and wavemaker stroke (of a harmonically oscillating wavemaker) are known, then the wavemaker theory predicts the wave motion everywhere, and in particular the wave height a few depths away from the wavemaker.The experiments were conducted in a 100 ft. wave channel, and the wave-height envelope was measured with a combination hook-and-point gauge. A plane beach (sloping 1:15) to absorb the wave energy was located at the far end of the channel. The amplitude-reflexion coefficient was usually less than 10%. Unless this reflexion effect is corrected for, it imposes one of the most serious limitations upon experimental accuracy. In the analysis of the present set of measurements, the reflexion effect is taken into account.The first series of tests was concerned with verifying the wavemaker theory for waves of small steepness (0.002 ≤ H/L ≤ 0.03). For this range of wave steepnesses, the measured wave heights were found to be on the average 3.4% below the height predicted by theory. The experimental error, as measured by the scatter about aline 3.4% below the theory, was of the order of 3%. The systematic deviation of 3.4% is believed to be partly due to finite-amplitude effects and possibly to imperfections in the wavemaker motion.The second series of tests was concerned with determining the effects of finite amplitude. For therange of wave steepnesses 0.045 ≤ H/L ≤ 0.048, themeasured wave heights were found to be on the average 10% below the heightspredictedfrom the small-amplitude theory. The experimental error was again of the order of 3%.It is considered that these measurements confirm the validity of the small-amplitude wave theory. No confirmation of this accuracy has hitherto been given for forced motions.

scholarly journals WAVE SET-UP IN THE SURF ZONE

1978 ◽  
Vol 1 (16) ◽  
pp. 62
Author(s):  
Uwe A. Hansen
Keyword(s):  
Water Level ◽  
Dynamic Load ◽  
Static Load ◽  
Surf Zone ◽  
Wave Heights ◽  
Level Elevation ◽  
Set Up ◽  
Protective Structures ◽  
The Waves ◽  
Design Water Level

In designing coastal protective structures the knowledge of the static load due to the water level elevation is as important as that of the dynamic load due to the waves. The structure, designed at sandy coasts with well formed surf zones on the beach - these areas are the basis of this examination - has to stand against both, the superposition of the static and dynamic load, which are dependent on each other. Undoubtedly a rise in the design water level (a summation of different influences - see figure 1) will cause an increase in the wave heights and the reverse will happen, when the design water level decreases.

scholarly journals FLUME EXPERIMENTS ON SAND TRANSPORT BY WAVES AND CURRENTS

2011 ◽  
Vol 1 (8) ◽  
pp. 11 ◽  
Author(s):  
Douglas L. Inman ◽  
Anthony J. Bowen
Keyword(s):  
Wave Height ◽  
Fold Increase ◽  
Total Power ◽  
Sand Transport ◽  
Flume Experiments ◽  
Wave Travel ◽  
Solid Discharge ◽  
Waves And Currents ◽  
The Waves

Measurements were made of the sand transport (solid discharge) caused by waves and currents traveling over a horizontal sand bed in water 50 cm deep. The waves had heights of 15 cm, and periods of 1.4 and 2.0 sec. The sand transport was measured first in the presence of waves only, then in the presence of waves superimposed on currents. The currents flowed in the direction of wave travel, with steady uniform velocities of 2, 4, and 6 cm/sec. Since sand moves to and fro under the influence of waves, sand traps were placed flush with the surface at either end of the bed. The net sand transport was determined by subtracting the amount of sand trapped at the upwave end of the bed, from that trapped at the downwave end. The total amount of sand caught in both traps was greatest with waves of 2.0 sec period, while the net sand transport was greatest with waves of 1.4 sec period. Super position of waves on currents of 2 cm/sec produced a two-fold increase in the sand transport for both wave types. Surprisingly, faster currents of 4 and 6 cm/sec caused the discharge to decrease somewhat. Estimates of the power expended by waves was obtained from the decrement in wave height as the wave traveled over the sand bed. The decrement in wave height was found to be about I0--5 per unit of distance traveled. Certain calculations show that about one tenth of the total power expended by the waves was used in transporting sediment.

scholarly journals COMPUTATIONS OF LONGSHORE CURRENTS

1964 ◽  
Vol 1 (9) ◽  
pp. 12
Author(s):  
Tsao-Yi Chiu ◽  
Per Bruun
Keyword(s):  
Wave Height ◽  
Wave Breaking ◽  
Surf Zone ◽  
Wave Spectrum ◽  
Wave Theory ◽  
Breaking Wave ◽  
Height Distribution ◽  
Longshore Current ◽  
Longshore Currents ◽  
Actual Height

This article introduces the longshore current computations based on theories published under the title "Longshore Currents and Longshore Troughs" (Bruun, 1963). Two approaches are used to formulate the longshore current velocities for a beach profile with one bar under the following assumptions: (1) that longshore current is evenly distributed (or a mean can be taken) along the depthj (2) that the solitary wave theory is applicable for waves in the surf zone; (3) that the statistical wave-height distribution for a deep water wave spectrum with a single narrow band of frequencies can be used near the shore, and (4) that the depth over the bar crest, Dcr, equal 0.8Hv/i /o\. Breaking wave height H^Q/^X is designated to be the actual height equal to Hw-j (significant wave height). Diagrams have been constructed for both approaches for beach profiles with one bar, from which longshore current velocities caused by various wave-breaking conditions can be read directly. As for longshore currents along the beach with a multibar system, fifteen diagrams covering a great variety of wave-breaking conditions are provided for obtaining longshore current velocities in different troughs.

scholarly journals WAVE HEIGHT MEASURING EQUIPMENT

2011 ◽  
Vol 1 (7) ◽  
pp. 7
Author(s):  
E.H. Boiten
Keyword(s):  
Wave Height ◽  
Water Surface ◽  
Measuring Equipment ◽  
Wave Motion ◽  
Sea Waves ◽  
Recording Equipment ◽  
Wave Measurements ◽  
Frequency Modulate ◽  
The Waves ◽  
Made In

The equipment was designed to obtain data from sea waves. It was developed by the Organization for Applied Scientific Research at Delft in coordination with the Royal Dutch Navy. The intention of the measurements with the wave height measuring equipment was to establish a correlation between the sea motion and the movements of a ship, which is steaming in that sea. So wave measurements and measurements of the ship movements were always carried out simultaneously. To have the movement of the ship free from the position of the wave meter, a telemetering system was chosen to transmit the data from the wave meter. The receiving and recording instruments are placed on board the ship. The first measurement was made in December 1958. At that moment, the wave meter consisted of a buoy assembly in which was mounted a transmitter coupled with an accelerometer. The accelerometer measured the accelerations of the wave meter in a direction perpendicular to the water surface. The carrier of the transmitter was direct frequency modulated by the signal of the accelerometer. After this measurement it became desirable to gather more data from the sea waves. For that reason the instrumentation of the wave meter was extended with a gyro, which measures the slope of the waves. The slope is determined by the angles of the water surface with respect to the horizontal plane in two directions perpendicular to each other. The angle signals frequency-modulate two subcarriers, which in their turn amplitude-modulated the transmitter carrier . With this more complicated equipment a measurement was made in November 1959. In this paper a description is given of the instrumentation of the wave meter and the receiving and recording equipment as it is at the present with a slightly changed modulating system. As the data from the wave meter could be used to study only the wave motion apart from the ship, it seems reasonable to present this paper at this conference.

Sign in / Sign up

Export Citation Format

Share Document