scholarly journals THE INTERACTION OF SMALL AND FINITE AMPLITUDE LONG WAVES AND CURRENTS

1984 ◽  
Vol 1 (19) ◽  
pp. 67 ◽  
Author(s):  
F. Raichlen ◽  
J.J. Lee
Keyword(s):  
Power Plants ◽  
Cooling Water ◽  
Breaking Waves ◽  
Finite Amplitude ◽  
Offshore Structure ◽  
Wave Refraction ◽  
Steady Current ◽  
Waves And Currents ◽  
The Waves ◽  
A Current

The interaction of waves and currents is important for many engineering problems. For example, when considering forces on marine structures, the velocity and acceleration field must be defined, and thus the manner in which a current interacts with small and finite amplitude waves must be understood. When the current is large and oblique to the waves, the direction of the force on an offshore structure may change significantly with depth introducing a torsional moment. Wave refraction and the concomitant attenuation or amplification of waves are also affected by offshore currents. An example is the effect on incident waves of offshore currents induced by the discharge of cooling water from coastal-sited power plants. This current can modify the direction and magnitude of approaching waves, and by these changes the breaking waves at the shore and the nearshore sediment transport associated with these waves may be changed. A number of theoretical studies have been conducted on various aspects of wave-current interactions; see Peregrine (1976). One theoretical study, Thomas (1981), will be used in this investigation. Careful experiments in this area are limited; several are: Iwagaki and Asano (1980), Sarpkaya (1957), and Thomas (1981). Each of these has given attention to certain aspects of small amplitude wave-current interactions. The experiments are difficult to conduct because of the problems inherent in introducing waves into a flume with a steadyuniform current or conversely a current into a wave tank with permanent waves. Certain features of these experimental problems can be seen through the following two examples. If a plunger-wave machine were used and located at one end of a flume in which a steady current is flowing, although the waves would be developing as they interact with the current, the previously steady current would be changed to an unsteady one by the periodic blockage of the flow by the plunger. If the waves are generated at one end of the tank and allowed to develop, and a current is introduced from the bottom of the tank, this current must expand to the full depth of the flow; hence, the waves propagate on a developing current. Therefore, comparisons to theory are, to some extent, difficult to realize, because the theory generally assumes wavecurrent interactions when each is fully developed.

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 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).

Wave–current interactions: an experimental and numerical study. Part 2. Nonlinear waves

1990 ◽  
Vol 216 ◽  
pp. 505-536 ◽  
Author(s):  
G. P. Thomas
Keyword(s):  
Numerical Study ◽  
Finite Depth ◽  
Finite Amplitude ◽  
Two Dimensions ◽  
Arbitrary Distribution ◽  
Current Interaction ◽  
Particle Velocities ◽  
The Waves ◽  
A Current ◽  
Theory And Experiment

The interaction between a regular wavetrain and a current possessing an arbitrary distribution of vorticity, in two dimensions, is considered for waves of finite amplitude. A numerical model is constructed, primarily for use in the finite depth regime, extending the work of Dalrymple (1973, 1977) and this is used to predict the wavelength and the particle velocities under the waves. These predictions agree very well with experimentally obtained data and the importance of the vorticity in the wave–current interaction is clarified. Amplitude and wavelength modulations are considered for finite amplitude waves on a slowly varying irrotational current; moderate agreement is found between theory and experiment.

scholarly journals REFRACTION OF FINITE-HEIGHT AND BREAKING WAVES

1976 ◽  
Vol 1 (15) ◽  
pp. 28 ◽  
Author(s):  
James R. Walker
Keyword(s):  
Three Dimensional ◽  
Wave Theory ◽  
Breaking Waves ◽  
Finite Amplitude ◽  
Primary Objective ◽  
Test Series ◽  
Data Sets ◽  
Linear Wave ◽  
Wave Refraction ◽  
Wave Shoaling

The primary objective of this study was to ascertain the influence of wave height and breaking on wave refraction over a three-dimensional shoal. The subject wave transformations were studied in an hydraulic model. Wave shoaling, decay in the breaker zone, and phase velocities were analyzed in a base test series over a bottom slope of 1:30. A second test series was conducted over a three-dimensional shoal. Wave patterns were photographed and wave heights and celerities were measured. The measurements were compared with wave refraction patterns and coefficients computed by analytical methods. Wave shoaling observed over the constant 1:30 slope was 25 percent greater than predicted by Airy theory at the breaking point for wave steepness H0/L0=.030 and 50 percent greater than predicted for H0/Lo = •002. Shoaling measurements were compared with other empirical data sets, confirming the inadequacy of commonly used practice using linear wave theory near the breaker zone. The celerity measurements indicated that the non-breaking celerity was given by C = (1+.25 H/d)Ca, where Ca is the Airy celerity. The discussion and results give a basic understanding of wave refraction near the breaker zone, supplementing analytical papers on refraction procedures using finite amplitude wave theories.

Harmonic Wave and Steady Current Effects on Plane Fishnets

2010 ◽  
Author(s):  
Cheslav Balash ◽  
Bruce Colbourne ◽  
Neil Bose ◽  
Jonathan Binns ◽  
Wayne Raman-Nair
Keyword(s):  
Drag Force ◽  
Harmonic Wave ◽  
Wave Length ◽  
Inertia Force ◽  
Wave Forces ◽  
Drag Forces ◽  
Combined Loads ◽  
Steady Current ◽  
The Waves ◽  
A Current

Individual and interaction effects of parallel current and waves on three plane nets were empirically examined. A current opposing the direction of the waves was shown to shorten the wavelength while a current in-line with the direction of the waves stretched the wave length. Due to these wave modifications, the combined loads produced by a current and waves were significantly less than the sum of current and wave forces applied individually. Applying a vector approach, the unsteady loads were split into drag forces and inertia components. Both components contributed considerably to the hydrodynamic loads for wave-only cases. For combinations of waves and current, the inertia force was significantly greater than the drag force. Further insights were also provided into the concepts of effective thickness and the modified Keulegan-Carpenter number as parameters quantifying inertia force and drag force for fishnets.

PHYSICAL INTERPRETATION OF WAVE BREAKING CRITERIA

2017 ◽  
Author(s):  
Sergey Kuznetsov ◽  
Sergey Kuznetsov ◽  
Yana Saprykina ◽  
Yana Saprykina ◽  
Boris Divinskiy ◽  
...  
Keyword(s):  
Nonlinear Wave ◽  
Wave Breaking ◽  
Second Harmonic ◽  
Vertical Axis ◽  
Breaking Waves ◽  
Wave Transformation ◽  
Spectral Structure ◽  
Similarity Parameter ◽  
Nonlinear Harmonics ◽  
The Waves

On the base of experimental data it was revealed that type of wave breaking depends on wave asymmetry against the vertical axis at wave breaking point. The asymmetry of waves is defined by spectral structure of waves: by the ratio between amplitudes of first and second nonlinear harmonics and by phase shift between them. The relative position of nonlinear harmonics is defined by a stage of nonlinear wave transformation and the direction of energy transfer between the first and second harmonics. The value of amplitude of the second nonlinear harmonic in comparing with first harmonic is significantly more in waves, breaking by spilling type, than in waves breaking by plunging type. The waves, breaking by plunging type, have the crest of second harmonic shifted forward to one of the first harmonic, so the waves have "saw-tooth" shape asymmetrical to vertical axis. In the waves, breaking by spilling type, the crests of harmonic coincides and these waves are symmetric against the vertical axis. It was found that limit height of breaking waves in empirical criteria depends on type of wave breaking, spectral peak period and a relation between wave energy of main and second nonlinear wave harmonics. It also depends on surf similarity parameter defining conditions of nonlinear wave transformations above inclined bottom.

scholarly journals Modification of Airflow Structure Due to Wave Breaking on a Submerged Topography

2021 ◽  
Author(s):  
Petter Vollestad ◽  
Atle Jensen
Keyword(s):  
Wind Wave ◽  
Separated Flow ◽  
Flow Region ◽  
Breaking Waves ◽  
Leeward Side ◽  
Geometrical Properties ◽  
Image Velocimetry ◽  
Wind Profiles ◽  
The Waves ◽  
Sheltered Area

AbstractExperimental results from a combined wind–wave tank are presented. Wind profiles and resulting wind–wave spectra are described, and an investigation of the airflow above breaking waves is presented. Monochromatic waves created by the wave maker are directed towards a submerged topography. This causes the waves to break at a predictable location, facilitating particle-image-velocimetry measurements of the airflow above steep breaking and non-breaking waves. We analyze how the breaking state modifies the airflow structure, and in particular the extent of the sheltered area on the leeward side of the waves. Results illustrate that while the geometrical properties of the waves greatly influence the airflow structure on the leeward side of the waves, the state of breaking (i.e., whether the waves are currently in a state of active breaking) is not observed to have a clear effect on the extent of the separated flow region, or on the velocity distribution within the sheltered region.

Riser Fatigue Due to Currents and Waves

2002 ◽  
Author(s):  
C. Le Cunff ◽  
E. Fontaine ◽  
F. Biolley
Keyword(s):  
Modal Analysis ◽  
Environmental Conditions ◽  
Navier Stokes ◽  
Vortex Induced Vibrations ◽  
Two Factors ◽  
Shedding Frequency ◽  
The Waves ◽  
Structural Mode ◽  
A Current

Fatigue due to environmental conditions is studied on a top-tensioned riser. The fatigue is due to two factors. First, the waves produce a displacement of the top of the riser, which excites the structure. Secondly, currents create vortices behind the structures. The phenomenon is then referred to as vortex-induced vibrations (VIV), whereby the vortices can lock onto a structural mode through the shedding frequency. In the present paper, we have two objectives. The first is to compare the fatigue estimates given either by a modal analysis or by Navier-Stokes calculations for a riser in a current. The second is to determine if studying the wave and current effects separately produces conservative results or if they must be studied together.

scholarly journals Ion chromatographic analysis of aqueous iodine species by conductivity and radioactivity measurements

2005 ◽  
Vol 93 (9-10) ◽  
Author(s):  
Dorothea Schumann ◽  
R. Grasser ◽  
R. Dressler ◽  
H. Bruchertseifer
Keyword(s):  
Chromatographic Analysis ◽  
Nuclear Power ◽  
Power Plants ◽  
Radioactive Iodine ◽  
Cooling Water ◽  
Molecular Iodine ◽  
New Device ◽  
Iodine Species ◽  
Radioactivity Measurements

SummaryA new device was developed for the identification of several iodine species in aqueous solution using ion chromatography. Iodide, iodate and molecular iodine can be determined. (The equipment allows both conductivity and radioactivity detections.) The method is applicable for the determination of radioactive iodine contaminations in the cooling water of nuclear power plants.

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