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.

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 LAMINAR DAMPING OF OSCILLATORY WAVES DUE TO BOTTOM FRICTION

1966 ◽  
Vol 1 (10) ◽  
pp. 10 ◽  
Author(s):  
Yuichi Iwagaki ◽  
Yoshito Tsuchiya
Keyword(s):  
Wave Amplitude ◽  
Experimental Studies ◽  
Bottom Friction ◽  
Laminar Boundary Layers ◽  
Wave Channel ◽  
Direct Measurements ◽  
Amplitude Attenuation ◽  
Side Walls ◽  
Basic Equations ◽  
Oscillatory Waves

The purpose of this paper is to discover the mechanism of the laminar damping of oscillatory waves due to bottom friction with the aid of the theory of the laminar boundary layer due to waves and of the measurements of instantaneous shearing stresses exerted on a smooth bottom, resulting from wave motion and wave amplitude attenuation with distance. In a theoretical approach the effects of convective terms involved in the basic equations of laminar boundary layers developing both on the bottom and the side walls of a wave channel, are considered on the basis of an approximate solution of the equation, and a theory of the laminar damping of Airy waves is established. In experimental studies, furthermore, direct measurements of instantaneous stresses and observations of wave amplitude attenuation were performed, and the experimental results are compared with both the above theory and the linearized one.

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

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.

Numerical Simulations of Interactions between Gravity Waves and Deep Moist Convection

2005 ◽  
Vol 62 (5) ◽  
pp. 1480-1496 ◽  
Author(s):  
Zachary A. Eitzen ◽  
David A. Randall
Keyword(s):  
Gravity Waves ◽  
Deep Convection ◽  
Velocity Versus ◽  
Moist Convection ◽  
Vertical Grid ◽  
Wave Energy Flux ◽  
Deep Moist Convection ◽  
Vertically Propagating ◽  
The Tropics ◽  
The Waves

Abstract This study uses a numerical model to simulate deep convection both in the Tropics over the ocean and the midlatitudes over land. The vertical grid that was used extends into the stratosphere, allowing for the simultaneous examination of the convection and the vertically propagating gravity waves that it generates. A large number of trajectories are used to evaluate the behavior of tracers in the troposphere, and it is found that the tracers can be segregated into different types based upon their position in a diagram of normalized vertical velocity versus displacement. Conditional sampling is also used to identify updrafts in the troposphere and calculate their contribution to the kinetic energy budget of the troposphere. In addition, Fourier analysis is used to characterize the waves in the stratosphere; it was found that the waves simulated in this study have similarities to those observed and simulated by other researchers. Finally, this study examines the wave energy flux as a means to provide a link between the tropospheric behavior of the convection and the strength of the waves in the stratosphere.

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