scholarly journals REACH OF WAVES TO THE BED OF THE CONTINENTAL SHELF

1970 ◽  
Vol 1 (12) ◽  
pp. 40 ◽  
Author(s):  
Richard Silvester ◽  
Geoffrey R. Mogridge
Keyword(s):  
Boundary Layer ◽  
Continental Shelf ◽  
Surf Zone ◽  
Sediment Concentration ◽  
Geologic Time ◽  
Continental Shelves ◽  
Transport Velocity ◽  
Mass Transport Velocity ◽  
Wave Boundary ◽  
The Waves

The physiography of Continental Shelves and their major composition of sediment indicate strongly their terrigenous origin and their smoothing by wave action This premise is supported by the geologic time over which waves have existed and the mass-transport velocity in these relatively shallow depths, particularly the net movement within the wave boundary layer at the bed A given wave tram arriving obliquely to the shore can transport material along the coast, both beyond the breaker line and within the surf zone It is shown that for equal over-all discharge in the two zones, the average sediment concentration offshore close to the bed need be reasonably small, indicating that transport near the beach could be a fraction of that from the breakers to the reach of the waves This latter limit is shown to extend at least half way across the Shelf, with possibilities of greater reach when more realistic prototype conditions are introduced into experiments.

Mass transport in water waves over an elastic bed

1995 ◽  
Vol 450 (1939) ◽  
pp. 371-390 ◽  
Keyword(s):  
Boundary Layer ◽  
Free Surface ◽  
Mass Transport ◽  
Water Waves ◽  
Viscous Boundary Layer ◽  
Curvilinear Coordinate ◽  
Transport Velocity ◽  
Mass Transport Velocity ◽  
Orthogonal Curvilinear Coordinate System ◽  
Viscous Boundary

The mass transport velocity in water waves propagating over an elastic bed is investigated. Water is assumed to be incompressible and slightly viscous. The elastic bed is also incompressible and satisfies the Hooke’s law. For a small amplitude progressive wave perturbation solutions via a boundary-layer approach are obtained. Because the wave amplitude is usually larger than the viscous boundary layer thickness and because the free surface and the interface between water and the elastic bed are moving, an orthogonal curvilinear coordinate system (Longuet-Higgins 1953) is used in the analysis of free surface and interfacial boundary layers so that boundary conditions can be applied on the actual moving surfaces. Analytical solutions for the mass transport velocity inside the boundary layer adjacent to the elastic seabed and in the core region of the water column are obtained. The mass transport velocity above a soft elastic bed could be twice of that over a rigid bed in the shallow water.

scholarly journals THB INFLUENCE OF WAVES OH CURRENT PROFILES

1986 ◽  
Vol 1 (20) ◽  
pp. 7 ◽  
Author(s):  
Felicity C. Coffey ◽  
Peter Nielsen
Keyword(s):  
Boundary Layer ◽  
Friction Velocity ◽  
Dimensionless Parameter ◽  
Velocity Amplitude ◽  
Steady Current ◽  
Vertical Scale ◽  
Flow Components ◽  
Current Reduction ◽  
Wave Boundary ◽  
The Waves

A simple model is presented for steady current profiles in the presence of waves. The current reduction and apparent roughness increase caused by the waves are shown to depend mainly on one dimensionless parameter u*/u"*, i.e. the ratio between the friction velocity amplitude due to the waves and the time averaged friction velocity. The model recognises the need to apply different eddy viscosities to different flow components. Also, the thickness of the wave influenced layer near the bed is comceptually separated from the vertical scale of the wave boundary layer.

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.

On the decrease of velocity with depth in an irrotational water wave

1953 ◽  
Vol 49 (3) ◽  
pp. 552-560 ◽  
Author(s):  
M. S. Longuet-Higgins
Keyword(s):  
Periodic Motion ◽  
Water Wave ◽  
Pressure Fluctuations ◽  
Periodic Wave ◽  
Finite Amplitude ◽  
Transport Velocity ◽  
Mean Pressure ◽  
Mass Transport Velocity ◽  
The Mean ◽  
The Waves

ABSTRACTThe following theorems are proved for irrotational surface waves of finite amplitude in a uniform, incompressible fluid:(a) In any space-periodic motion (progressive or otherwise) in uniform depth, the mean square of the velocity is a decreasing function of the mean depth z below the surface. Hence the fluctuations in the mean pressure increase with z.(b) In any space-periodic motion in infinite depth, the particle motion tends to zero exponentially as z tends to infinity. The pressure fluctuations at great depths are therefore simultaneous, but they do not in general tend to zero.(c) In a progressive periodic wave in uniform depth the mass-transport velocity is a decreasing function of the mean depth of a particle below the free surface, and the tangent to the velocity profile is vertical at the bottom. This result conflicts with observations in wave tanks, and shows that the waves cannot be wholly irrotational.(d) Analogous results are proved for the solitary wave.

scholarly journals NUMERICAL MODEL OF CURRENT AND SEDIMENT TRANSPORT IN THE WAVE BOUNDARY LAYER

2011 ◽  
Vol 1 (32) ◽  
pp. 5
Author(s):  
Yuliang Zhu ◽  
Jing Ma ◽  
Hao Wang
Keyword(s):  
Boundary Layer ◽  
Mathematical Model ◽  
Eddy Viscosity ◽  
Sediment Concentration ◽  
Wave Boundary Layer ◽  
Time Invariant ◽  
Wave Boundary ◽  
The Mathematical Model ◽  
The Relationship ◽  
Turbulent Wave

Mathematical model is one of the means to study of turbulent wave boundary layer. The paper analysis of the existing model, adopt a more reasonable boundary condition to establish a improved mathematical model of 1DV turbulent wave boundary layer using k-ε model. The paper recommends brief flow simulation and mainly introduced the simulation of the sediment concentration. The paper use the eddy-viscosity value which calculation by the mathematical model and the model of You Zaijin on time-invariant eddy-viscosity into the relationship about sediment diffusion coefficient and eddy-viscosity to calculate the sediment concentration. The calculation results turns out the way that use the eddy-viscosity value which calculation by the mathematical model into the relationship can obtain better timely sediment concentration value. When use the model simulates the time-invariant sediment concentration, the two ways have not many distinctions. It means the way that that use the eddy-viscosity value which calculation by the mathematical model into the relationship is feasible.

On the mass transport induced by oscillatory flow in a turbulent boundary layer

1970 ◽  
Vol 43 (1) ◽  
pp. 177-185 ◽  
Author(s):  
B. Johns
Keyword(s):  
Boundary Layer ◽  
Turbulent Boundary Layer ◽  
Mass Transport ◽  
Eddy Viscosity ◽  
Oscillatory Flow ◽  
Standing Waves ◽  
Turbulent Layer ◽  
Transport Velocity ◽  
Mass Transport Velocity ◽  
Limiting Value

Oscillatory flow in a turbulent boundary layer is modelled by using a coefficient of eddy viscosity whose value depends upon distance from a fixed boundary. A general oscillatory flow is prescribed beyond the layer, and the model is used to calculate the mass transport velocity induced by this within the layer. The result is investigated numerically for a representative distribution of eddy viscosity and the conclusions interpreted in terms of the mass transport induced by progressive and standing waves. For progressive waves, the limiting value of the mass transport velocity at the outer edge of the layer is the same as for laminar flow. For standing waves, the limiting value is reduced relative to its laminar value but, within the lowermost 25% of the layer, there is a drift which is reversed relative to the limiting value. This is considerably stronger than its counterpart in the laminar case and, in view of the greater thickness of the turbulent layer, it may make a dominant contribution to the net movement of loose bed material by a standing wave system.

scholarly journals A PRE-DREDGING SAND MOBILITY STUDY USING A RADIOISOTOPE TRACER

1984 ◽  
Vol 1 (19) ◽  
pp. 138
Author(s):  
A. Davison
Keyword(s):  
Sand Transport ◽  
Dispersion Pattern ◽  
Tracer Dispersion ◽  
Navigation Channel ◽  
Transport Velocity ◽  
Mass Transport Velocity ◽  
The Mean ◽  
Wave Boundary ◽  
Mobility Study ◽  
Radioisotope Tracer

The wave-driven movement of sand across the alignment of a proposed navigation channel was investigated using radioactive chromium-51 labelled tracer sand. The mean particle velocity and thickness of the mobile layer were determined over a two-month period, and an annual infill rate estimated. Wave height and period were measured concurrently. Despite two storms, during which near-bed oscillating velocities of 1.5 m s-1 were calculated the sand transport at 10 m (BMWL) appears to occur within the wave boundary layer. Onshore transport in the direction of wave propagation, due to mass transport velocity and wave asymmetry effects, was easily identified. Tidal currents up to 1.2 m s-1 (at 3 m above bed) had less than the expected effect on the tracer dispersion pattern.

Mass transport in a turbulent boundary layer under a progressive water wave

1984 ◽  
Vol 146 ◽  
pp. 303-312 ◽  
Author(s):  
S. J. Jacobs
Keyword(s):  
Boundary Layer ◽  
Mass Transport ◽  
Water Wave ◽  
Approximate Solutions ◽  
Reynolds Numbers ◽  
Bottom Boundary Layer ◽  
Bottom Boundary ◽  
Transport Velocity ◽  
Mass Transport Velocity ◽  
Theoretical Results

The bottom boundary layer under a progressive water wave is studied using Saffman's turbulence model. Saffman's equations are analysed asymptotically for the case Re [Gt ] 1, where Re is a Reynolds number based on a characteristic magnitude of the orbital velocity and a characteristic orbital displacement. Approximate solutions for the mass-transport velocity at the edge of the boundary layer and for the bottom stress are obtained, and Taylor's formula for the rate of energy dissipation is verified. The theoretical results are found to agree well with observations for sufficiently large Reynolds numbers.

Double boundary layers in standing interfacial waves

1976 ◽  
Vol 76 (4) ◽  
pp. 819-828 ◽  
Author(s):  
B. D. Dore
Keyword(s):  
Boundary Layer ◽  
Mass Transport ◽  
Layer Structure ◽  
Standing Waves ◽  
Boundary Layer Theory ◽  
Two Dimensional ◽  
Transport Velocity ◽  
Oscillatory Velocity ◽  
Mass Transport Velocity ◽  
The Mean

The double-boundary-layer theory of Stuart (1963, 1966) and Riley (1965, 1967) is employed to investigate the mass transport velocity due to two-dimensional standing waves in a system comprising two homogeneous fluids of different densities and viscosities. The most important double-boundary-layer structure occurs in the neighbourhood of the oscillating interface, and the possible existence of jet-like motions is envisaged at nodal positions, owing to the nature of the mean flows in the layers. In practice, the magnitude of the mass transport velocity can be a significant fraction of that of the primary, oscillatory velocity.

Mass transport in the bottom boundary layer of cnoidal waves

1976 ◽  
Vol 74 (3) ◽  
pp. 401-413 ◽  
Author(s):  
M. De St Q. Isaacson
Keyword(s):  
Boundary Layer ◽  
Mass Transport ◽  
Wave Theory ◽  
Bottom Boundary Layer ◽  
Inviscid Fluid ◽  
Viscous Boundary Layer ◽  
Cnoidal Waves ◽  
Bottom Boundary ◽  
Transport Velocity ◽  
Mass Transport Velocity

This study deals with the mass-transport velocity within the bottom boundary layer of cnoidal waves progressing over a smooth horizontal bed. Mass-transport velocity distributions through the boundary layer are derived and compared with that predicted by Longuet-Higgins (1953) for sinusoidal waves. The mass transport at the outer edge of the boundary layer is compared with various theoretical results for an inviscid fluid based on cnoidal wave theory and also with previous experimental results. The effect of the viscous boundary layer is to establish uniquely the bottom mass transport and this is appreciably greater than the somewhat arbitrary prediction for an inviscid fluid.

Sign in / Sign up

Export Citation Format

Share Document