Influence of surface gravity waves on wind-driven circulation in intermediate depths on an exposed coast

1990 ◽  
Vol 41 (3) ◽  
pp. 353 ◽  
Author(s):  
KP Black ◽  
PE McShane
Keyword(s):  
Gravity Waves ◽  
Interaction Theory ◽  
Linear Interaction ◽  
Waves And Currents ◽  
Order Of Magnitude ◽  
Current Interaction ◽  
Wind Driven Currents ◽  
The Waves ◽  
Bed Friction ◽  
Systematic Reduction

Coastal experiments in 18 m depths showed the systematic reduction of wind-driven longshore currents in the presence of surface waves. Predicted wind-driven currents were found to be nearly an order of magnitude greater than measurements if the wave influence was neglected. However, satisfactory predictions were made when the increased effective bed friction due to the non-linear interaction between the waves and currents was accounted for. This paper assesses the applicability of wave/current interaction theory to natural open-coast environments. The results are relevant to the prediction of dispersal (e.g. of pollutants or larvae) on open coasts.

scholarly journals INTERACTION OF WAVES AND A TURBULENT CURRENT

1976 ◽  
Vol 1 (15) ◽  
pp. 22 ◽  
Author(s):  
J.D.A. Van Hoften ◽  
S. Karaki
Keyword(s):  
Experimental Investigation ◽  
Gravity Waves ◽  
Wave Amplitude ◽  
Current System ◽  
Bottom Shear Stress ◽  
Wave Dissipation ◽  
Wave Channel ◽  
Amplitude Attenuation ◽  
Current Interaction ◽  
The Waves

An experimental investigation was made to study wave-current interaction. Wave amplitude attenuation was measured along a laboratory wave channel to compare wave dissipation with and without flow. Mean, wave, and turbulent velocities were also measured to determine the modifications of the flow imposed by the gravity waves propogating with the current. The process of energy transfer in the wave current system was studied. Energy was found to be extracted from the waves, diffused downward and dissipated by an increase in bottom shear stress.

scholarly journals WAVE AND CURRENT INTERACTION IN THE NEAR BED REGION

1982 ◽  
Vol 1 (18) ◽  
pp. 27
Author(s):  
Patrick H. Kemp ◽  
Richard R. Simons
Keyword(s):  
Sediment Transport ◽  
Shear Stresses ◽  
Mean Velocity ◽  
Wave Channel ◽  
Rough Bed ◽  
Waves And Currents ◽  
Transport Behaviour ◽  
Current Interaction ◽  
Areas Of Interest ◽  
The Waves

The question of how waves and currents interact, especially in the near-bed region is of considerable importance in relation to sediment suspension and sediment transport. Whereas empirical relationships provide useful estimates and indications in relation to the data on which they are based, a more thorough understanding of the physical processes at work is necessary for interpreting sediment transport behaviour in a more generalized way. Clearly the conditions under which flow reversal occurs near the bed, and also the extent to which wave motion may modify the current induced turbulence in the boundary layer, are both of great interest, and these and other aspects have been included in the present study. The research program was designed to look initially at the interaction between waves and currents in the absence of sediment, in order to define the mean velocity components, the structure of the turbulence, and the shear stresses. The study proceeded from experiments on waves alone, to waves propagating with the current and against the current. In all three cases the tests were carried out in the first instance with a smooth bed and subsequently with a rough bed consisting of two dimensional triangular slats. One of the main areas of interest was the height to which the water was disturbed above the bed when acted on by waves alone, and the comparable situation when a current was superimposed on the waves. Since the characteristics of the turbulent current were measured independently, it was possible to deduce whether there had been any interaction between the waves and the current, and also to infer what might happen to the distribution of the sediment which it was assumed would be put into suspension in the two cases. In the second stage of the research separate experiments were carried out in a standing wave channel and an oscillating water tunnel, using lightweight bed materials, in order to observe whether the inferences made from the clear water study were borne out by comparable changes in the distribution of the sediment in suspension.

Shoreface-connected ridges under the action of waves and currents

2007 ◽  
Vol 582 ◽  
pp. 23-52 ◽  
Author(s):  
EMILY M. LANE ◽  
JUAN M. RESTREPO
Keyword(s):  
Potential Problem ◽  
Orbital Velocity ◽  
Wave Forcing ◽  
Wave Parameters ◽  
The World ◽  
Bed Form ◽  
Waves And Currents ◽  
Current Interaction ◽  
Wave Orbital Velocity ◽  
The Waves

Up-current-rotated, shoreface-connected ridges are found in various coastal areas around the world. An often-quoted conjecture is that these ridges form during storm conditions through free instabilities in the erodible bed. Under these conditions both waves and currents are expected to play a significant role in the hydrodynamics. Although some existing models have included the effects of waves parametrically in their bottom friction terms and sediment equations, the dynamical effects of wave–current interaction have not been explored. In this paper we begin to rectify this by considering the effects of wave–current interaction on the bed-form instabilities of a simple model. This raises the possibility of unsteady alongshore flows and questions about the roles of wave parameters and boundary conditions, which we address here. We show that the flow is stable under the wave forcing; however the waves do affect the bed-form instability. The main dynamical effect of the waves is in altering the shapes of the unstable modes. Under various conditions, however, waves may enhance or suppress the instability or introduce new unstable modes. They also affect the celerity of the ridges. In addition, we investigate the mechanisms whereby the waves affect the instability. We also show a potential problem with the parameterization in terms of wave orbital velocity.

A simple model of wave–current interaction

2015 ◽  
Vol 775 ◽  
pp. 328-348 ◽  
Author(s):  
Nicoletta Tambroni ◽  
Paolo Blondeaux ◽  
Giovanna Vittori
Keyword(s):  
Wave Propagation ◽  
Perturbation Approach ◽  
Wave Steepness ◽  
One Dimensional ◽  
Steady Current ◽  
Order Of Magnitude ◽  
Current Interaction ◽  
Viscous Boundary ◽  
The Waves ◽  
Theoretical Results

The interaction between a steady current and propagating surface waves is investigated by means of a perturbation approach, which assumes small values of the wave steepness and considers current velocities of the same order of magnitude as the amplitude of the velocity oscillations induced by wave propagation. The problems, which are obtained at the different orders of approximation, are characterized by a further parameter which is the ratio between the thickness of the bottom boundary layer and the length of the waves and turns out to be even smaller than the wave steepness. However, the solution is determined from the bottom up to the free surface, without the need to split the fluid domain into a core region and viscous boundary layers. Moreover, the procedure, which is employed to solve the problems at the different orders of approximation, reduces them to one-dimensional problems. Therefore, the solution for arbitrary angles between the direction of the steady current and that of wave propagation can be easily obtained. The theoretical results are compared with experimental measurements; the fair agreement found between the model results and the laboratory measurements supports the model findings.

scholarly journals Influence of the cloud-level neutral layer on the vertical propagation of topographically generated gravity waves on Venus

2019 ◽  
Vol 71 (1) ◽  
Author(s):  
Takeru Yamada ◽  
Takeshi Imamura ◽  
Tetsuya Fukuhara ◽  
Makoto Taguchi
Keyword(s):  
Layer Thickness ◽  
Gravity Wave ◽  
Local Time ◽  
Gravity Waves ◽  
Analytical Approach ◽  
Wave Activity ◽  
Neutral Layer ◽  
Low Latitudes ◽  
Vertical Propagation ◽  
The Waves

AbstractThe reason for stationary gravity waves at Venus’ cloud top to appear mostly at low latitudes in the afternoon is not understood. Since a neutral layer exists in the lower part of the cloud layer, the waves should be affected by the neutral layer before reaching the cloud top. To what extent gravity waves can propagate vertically through the neutral layer has been unclear. To examine the possibility that the variation of the neutral layer thickness is responsible for the dependence of the gravity wave activity on the latitude and the local time, we investigated the sensitivity of the vertical propagation of gravity waves on the neutral layer thickness using a numerical model. The results showed that stationary gravity waves with zonal wavelengths longer than 1000 km can propagate to the cloud-top level without notable attenuation in the neutral layer with realistic thicknesses of 5–15 km. This suggests that the observed latitudinal and local time variation of the gravity wave activity should be attributed to processes below the cloud. An analytical approach also showed that gravity waves with horizontal wavelengths shorter than tens of kilometers would be strongly attenuated in the neutral layer; such waves should originate in the altitude region above the neutral layer.

Effects of wave-current interaction on the waves, cold-water mass and transport of diluted water in the Beibu Gulf

2020 ◽  
Vol 39 (1) ◽  
pp. 25-40
Author(s):  
Jingling Yang ◽  
Shaocai Jiang ◽  
Junshan Wu ◽  
Lingling Xie ◽  
Shuwen Zhang ◽  
...  
Keyword(s):  
Water Mass ◽  
Cold Water ◽  
Beibu Gulf ◽  
Cold Water Mass ◽  
Current Interaction ◽  
The Waves

Numerical Modeling of Seabed Response to Combined Wave-Current Loading

2013 ◽  
Vol 135 (3) ◽  
Author(s):  
J.-S. Zhang ◽  
Y. Zhang ◽  
C. Zhang ◽  
D.-S. Jeng
Keyword(s):  
Numerical Modeling ◽  
Stokes Equations ◽  
Navier Stokes ◽  
Laboratory Measurements ◽  
Navier Stokes Equations ◽  
Closure Scheme ◽  
Waves And Currents ◽  
Current Interaction ◽  
Wave Maker ◽  
Current Loading

In this paper, a numerical model is developed to study the dynamic response of a porous seabed to combined wave-current loadings. While the Reynolds-averaged Navier–Stokes equations with k-ε turbulence closure scheme and internal wave-maker function are solved for the phenomenon of wave-current interaction, Biot's poro-elastic “u-p” model is adopted for the seabed response. After validated by the laboratory measurements, this model is applied for the investigation of the effects of waves and currents on the wave-current induced pore pressures. Furthermore, the effects of currents on maximum liquefaction depths of a porous seabed is examined, and it is concluded that the opposite currents will increase the liquefaction depth up to 30% of that without currents.

scholarly journals Observation of mesospheric gravity waves at Comandante Ferraz Antarctica Station (62° S)

2009 ◽  
Vol 27 (6) ◽  
pp. 2593-2598 ◽  
Author(s):  
J. V. Bageston ◽  
C. M. Wrasse ◽  
D. Gobbi ◽  
H. Takahashi ◽  
P. B. Souza
Keyword(s):  
Gravity Waves ◽  
Weather Conditions ◽  
Propagation Direction ◽  
Cyclonic Activity ◽  
Wave Source ◽  
Cold Fronts ◽  
Wave Velocities ◽  
Orographic Forcing ◽  
Sky Imager ◽  
The Waves

Abstract. An airglow all-sky imager was operated at Comandante Ferraz Antarctica Station (62.1° S, 58.4° W), between April and October of 2007. Mesospheric gravity waves were observed using the OH airglow layer during 43 nights with good weather conditions. The waves presented horizontal wavelengths between 10 and 60 km and observed periods mainly distributed between 5 and 20 min. The observed phase speeds range between 5 m/s and 115 m/s; the majority of the wave velocities were between 10 and 60 m/s. The waves showed a preferential propagation direction towards the southwest in winter (May to July), while during spring (August to October) there was an anisotropy with a preferential propagation direction towards the northwest. Unusual mesospheric fronts were also observed. The most probable wave source could be associated to orographic forcing, cold fronts or strong cyclonic activity in the Antarctica Peninsula.

scholarly journals COMPARISON OF WAVE ACTIVITY IN THE MESOPAUSE REGION AT MAIMAGA STATION WITH EOS MLS (AURA) TEMPERATURE DATA AND ACTIVITY OF PLANETARY WAVES AT TIKSI STATION

2019 ◽  
pp. 182-189
Author(s):  
В.И. Сивцева ◽  
П.П. Аммосов ◽  
Г.А. Гаврильева ◽  
И.И. Колтовской ◽  
А.М. Аммосова
Keyword(s):  
Gravity Waves ◽  
Internal Gravity Waves ◽  
Temperature Data ◽  
Planetary Waves ◽  
Winter Period ◽  
Temperature Profiles ◽  
Night Temperature ◽  
Mesopause Region ◽  
The Difference ◽  
The Waves

Исследованы данные температуры области мезопаузы, полученные за период 2013-2018 гг. на станции Маймага (63.04N, 129.51E) и за период 2015-2018 гг. на станции Тикси (71.58 N, 128.77 E). В зимний период сезона наблюдений 2014-2015 характеристика активности внутренних гравитационных волн (ВГВ) gwимеет более низкие значения, чем в другие сезоны, а средненочная температура, наоборот, превышает аналогичные значения в другие сезоны. Для сопоставления рассматривались спутниковые данные температурных профилей полученные EOS MLS (Aura). После выделения и вычитания вклада гравитационной составляющей из температурных профилей EOS MLS для области над станцией Маймага заметно отличие в зимней стратопаузе сезона 2014-2015. В этот сезон в зимний период, с учетом вычета вклада флуктуаций температуры обусловленных ВГВ, наблюдается отсутствие резких потеплений в районе стратопаузы в отличие от остальных сезонов. Измерение параметров планетарных волн в течение периода 2015-2018 гг. совместных наблюдений на станциях Маймага и Тикси показали, что фазы наблюдаемых на обеих станциях волн совпадают, а амплитуды на станции Тикси несколько (12 К) превышают амплитуды на станции Маймага. The temperature data of the mesopause region obtained for the period 2013-2018 at the station Maimaga (63.04 N, 129.51 E) and for the period 2015-2018 at the station Tiksi (71.58 N, 128.77 E) was investigated. During the winter period of the 20142015 observation season, the characteristic of the internal gravity waves (IGW) activity sgw has lower values than in other seasons, and the average night temperature of the mesopause region, on the contrary, exceeds corresponding values in other seasons. For comparison, satellite data of temperature profiles obtained by EOS MLS (Aura) are given. After isolating and subtracting the contribution of the gravitaty waves from the EOS MLS temperature profiles for the region above the st. Maimaga, the difference in the winter stratopause of the 2014-2015 season is noticeable. In this season in winter there is a lack of sharp warming in the stratopause region, in contrast to other seasons, taking into account the deduction of the contribution of temperature fluctuations due to IGW. Measurement of the parameters of planetary waves during the period 2015-2018 of joint observations at Maimaga and Tiksi stations showed that the phases of the waves observed at both stations coincide, and the amplitudes at Tiksi station are several (1-2 K) higher than the amplitudes at Maimaga station.

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