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.

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.

Sediment transport by waves and currents

1983 ◽  
Vol 10 (1) ◽  
pp. 142-149 ◽  
Author(s):  
Michael C. Quick
Keyword(s):  
Sediment Transport ◽  
Mass Transport ◽  
Power Relationship ◽  
Zero Current ◽  
Transport Direction ◽  
Transport Velocity ◽  
Waves And Currents ◽  
Mass Transport Velocity ◽  
Combined Action ◽  
The Waves

Sediment transport is measured under the combined action of waves and currents. Measurements are made with currents in the direction of wave advance and with currents opposing the wave motion. Theoretical relationships are considered that predict the wave velocity field and the mass transport velocity for zero current and for steady currents.Following Bagnold's approach, a transport power relationship is developed to predict the sediment transport rate. Making assumptions for the mass transport velocity, the transport power is shown to agree with the measured sediment transport rates. It is particularly noted that the sediment transport direction is mainly determined by the direction of wave movement, even for adverse currents, until the waves start to break. Keywords: sediment transport, waves and currents, coastal engineering.

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 Sediment Transport Beyond the Surf Zone Under Waves and Currents of the Non-Tidal Sea: Lubiatowo (Poland) Case Study

2016 ◽  
Vol 63 (1) ◽  
pp. 63-77 ◽  
Author(s):  
Rafał Ostrowski ◽  
Magdalena Stella
Keyword(s):  
Sediment Transport ◽  
Surf Zone ◽  
Coastal Region ◽  
Wave Climate ◽  
Soil Parameters ◽  
Shear Stresses ◽  
Research Station ◽  
Sea Bed ◽  
Waves And Currents ◽  
Bed Changes

Abstract The paper deals with the sandy coastal zone at Lubiatowo in Poland (the south Baltic Sea). The study comprises experimental and theoretical investigations of hydrodynamic and lithodynamic processes in the coastal region located close to the seaward boundary of the surf zone and beyond the surf zone. The analysis is based on field data collected at the IBW PAN Coastal Research Station in Lubiatowo. The data consist of wind velocity reconstructed from the long-term wave climate, deep-water wave buoy records and sea bottom soil parameters. Nearbed flow velocities induced by waves and currents, as well as bed shear stresses are theoretically modelled for various conditions to determine sediment motion regimes in the considered area. The paper discusses the possibility of occasional intensive sediment transport and the occurrence of distinct sea bed changes at bigger water depths.

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 Numerical Study of the Hydrodynamics of Waves and Currents and Their Effects in Pier Scouring

Water ◽  
2019 ◽  
Vol 11 (11) ◽  
pp. 2256 ◽  
Author(s):  
Matias Quezada ◽  
Aldo Tamburrino ◽  
Yarko Niño
Keyword(s):  
Experimental Data ◽  
Relative Velocity ◽  
Numerical Study ◽  
Numerical Data ◽  
Navier Stokes ◽  
Shear Stresses ◽  
Numeric Modeling ◽  
Waves And Currents ◽  
Cylindrical Piles ◽  
The Waves

The scour around cylindrical piles due to codirectional and opposite waves and currents is studied with Reynolds Averaged Navier–Stokes (RANS) equations via REEF3D numeric modeling. First, a calibration process was made through a comparison with the experimental data available in the literature. Subsequently, not only the hydrodynamics, but also the expected scour for a set of scenarios, which were defined by the relative velocity of the current ( U C W ), were studied numerically. The results obtained show that the hydrodynamics around the pile for codirectional or opposite waves and currents not have significant differences when analyzed in terms of their velocities, vorticities and mean shear stresses, since the currents proved to be more relevant compared to the net flow. The equilibrium scour, estimated by the extrapolation of the numerical data with the equation by Sheppard, enabled us to estimate values close to those described in the literature. From this extrapolation, it was verified that the dimensionless scour would be less when the waves and currents are from opposite directions. The U C W parameter is an indicator used to adequately measure the interactions between the currents and waves under conditions of codirectional flow. Nevertheless, it is recommended to modify this parameter for currents and waves in opposite directions, and an equation is proposed for this case.

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.

scholarly journals The interaction between waves and a turbulent current: waves propagating with the current

1982 ◽  
Vol 116 ◽  
pp. 227-250 ◽  
Author(s):  
P. H. Kemp ◽  
R. R. Simons
Keyword(s):  
Wave Attenuation ◽  
Smooth Boundary ◽  
Order Theory ◽  
Velocity Profiles ◽  
Shear Stresses ◽  
Rough Boundary ◽  
Reynolds Stresses ◽  
Linear Superposition ◽  
Mean Velocity ◽  
The Waves

This paper describes an experimental programme carried out in a laboratory channel with rough and smooth beds, to investigate the interaction between gravity waves and a turbulent current. In particular, changes induced in the mean-velocity profiles, turbulent fluctuations, bed shear stresses and wave attenuation rates are considered for a range of wave heights, keeping the wave period constant. The smooth-boundary tests were carried out as a necessary preliminary to the more-realistic rough-boundary condition.A directionally sensitive laser anemometer was used to measure horizontal, vertical, and 45° velocity components in the oscillating fluid, and an on-line minicomputer was programmed to produce ensemble averages of velocities, Reynolds stresses and wave-elevation data. The cycle was sampled at 200 separate phase positions, with 180 observations at each position. Measurements were made at up to 30 points in the vertical.Preliminary tests were carried out on the unidirectional current and on the waves alone. These show that mean-velocity profiles and turbulence parameters of the current agree satisfactorily with previous experiments, and that the waves are approximated closely by Stokes’ second-order theory.For combined wave and current tests, mean-velocity profiles are generally found to differ from those suggested by a linear superposition of wave and current velocities, a change in boundary-layer thickness being indicated. However, shear stresses at the smooth boundary are found to be described by such a linear addition.

scholarly journals Stochastic Variational Formulations of Fluid Wave–Current Interaction

2020 ◽  
Vol 31 (1) ◽  
Author(s):  
Darryl D. Holm
Keyword(s):  
Drift Velocity ◽  
Fluid Velocity ◽  
Stokes Drift ◽  
Hamilton’S Principle ◽  
Hamilton's Principle ◽  
Mean Velocity ◽  
Lagrangian Transport ◽  
Transport Velocity ◽  
Current Interaction ◽  
The Waves

AbstractWe are modelling multiscale, multi-physics uncertainty in wave–current interaction (WCI). To model uncertainty in WCI, we introduce stochasticity into the wave dynamics of two classic models of WCI, namely the generalised Lagrangian mean (GLM) model and the Craik–Leibovich (CL) model. The key idea for the GLM approach is the separation of the Lagrangian (fluid) and Eulerian (wave) degrees of freedom in Hamilton’s principle. This is done by coupling an Euler–Poincaré reduced Lagrangian for the current flow and a phase-space Lagrangian for the wave field. WCI in the GLM model involves the nonlinear Doppler shift in frequency of the Hamiltonian wave subsystem, which arises because the waves propagate in the frame of motion of the Lagrangian-mean velocity of the current. In contrast, WCI in the CL model arises because the fluid velocity is defined relative to the frame of motion of the Stokes mean drift velocity, which is usually taken to be prescribed, time independent and driven externally. We compare the GLM and CL theories by placing them both into the general framework of a stochastic Hamilton’s principle for a 3D Euler–Boussinesq (EB) fluid in a rotating frame. In other examples, we also apply the GLM and CL methods to add wave physics and stochasticity to the familiar 1D and 2D shallow water flow models. The differences in the types of stochasticity which arise for GLM and CL models can be seen by comparing the Kelvin circulation theorems for the two models. The GLM model acquires stochasticity in its Lagrangian transport velocity for the currents and also in its group velocity for the waves. However, the CL model is based on defining the Eulerian velocity in the integrand of the Kelvin circulation relative to the Stokes drift velocity induced by waves driven externally. Thus, the Kelvin theorem for the stochastic CL model can accept stochasticity in its both its integrand and in the Lagrangian transport velocity of its circulation loop. In an “Appendix”, we also discuss dynamical systems analogues of WCI.

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