scholarly journals A FIELD INVESTIGATION OF SAND TRANSPORT IN THE SURF ZONE

1968 ◽  
Vol 1 (11) ◽  
pp. 22 ◽  
Author(s):  
Edward B. Thornton
Keyword(s):  
Energy Flux ◽  
Particle Motion ◽  
Field Experiments ◽  
Surf Zone ◽  
Field Investigation ◽  
Energy Spectra ◽  
Sand Transport ◽  
Bed Load ◽  
Water Particle ◽  
The Waves

The distribution of bed-load sand transport normal to the beach has been measured m a series of field experiments conducted in the surf zone at Fernandma Beach, Florida. Simultaneous measurements were made of the waves and water particle motion at various locations in the surf zone. The energy flux of the waves was resolved Into Its longshore component from the measured directional and energy spectra. It Is found that the bed-load transport is related to the depth of water and longshore energy flux. Insight into the mechanics of sediment transport is obtained by comparing the wave and water particle motion energy spectra, which give a direct measure of the kinetic and potential energy, at various locations in the surf zone.

scholarly journals TOWARD AN IMPROVED EMPIRICAL FORMULA FOR LONGSHORE SAND TRANSPORT

1988 ◽  
Vol 1 (21) ◽  
pp. 88 ◽  
Author(s):  
Nicholas C. Kraus ◽  
Kathryn J. Gingerich ◽  
Julie Dean Rosati
Keyword(s):  
Oscillatory Flow ◽  
Field Experiments ◽  
Surf Zone ◽  
Transport Rate ◽  
Sand Transport ◽  
Longshore Current ◽  
Wave Energy Dissipation ◽  
Total Transport ◽  
Local Wave ◽  
Correction Terms

This paper presents results of two field experiments performed using portable traps to obtain point measurements of the longshore sand transport rate in the surf zone. The magnitude of the transport rate per unit width of surf zone is found to depend on the product of the local wave height and mean longshore current speed, but correlation is much improved by including two correction terms, one accounting for local wave energy dissipation and the other for the fluctuation in the longshore current. The field transport rates are also found to be compatible with laboratory rates obtained under combined unidirectional and oscillatory flow. Total transport rates previously reported for this experiment program are revised with recently determined sand trapping efficiencies.

Field Experiments on Longshore Sand Transport in the Surf Zone

1982 ◽  
Author(s):  
Nicholas C. Kraus ◽  
Masahiko Isobe ◽  
Hajime Igarashi ◽  
Tamio O. Sasaki ◽  
Kiyoshi Horikawa
Keyword(s):  
Field Experiments ◽  
Surf Zone ◽  
Sand Transport

scholarly journals MODE AND PERIOD OF SAND TRANSPORT IN THE SURF ZONE

1974 ◽  
Vol 1 (14) ◽  
pp. 47 ◽  
Author(s):  
Benno M. Brenninkmeyer
Keyword(s):  
Deep Water ◽  
Water Wave ◽  
Surf Zone ◽  
Sediment Concentration ◽  
Sand Transport ◽  
Bed Load ◽  
Measuring Devices ◽  
Load Movement ◽  
Sand Movement ◽  
Deep Water Wave

Three almometers-water opacity measuring devices-emplaced perpendicular to the beach, measure instantaneously and continuously the sediment concentration across the surf zone. Most of the variance of the sand movement is centered in frequencies of less than 0.25 Hz and between 1.15 and 1.25 Hz. Modes and frequency of sand transport differ within each of the dynamic zones of the surf. The motion of sediment in the inner and outer surf zones is small and virtually independent of the deep water wave periods. Outside the breaker zone, bed load movement is somewhat coincident with the prevailing swell period. Lighter concentrations move predominantly with a 0.8-0.9 second periodicity. In the breaker zone, sand moves along the bottom with frequencies equal to that of both the swell and sea, but most of the power is in lower frequencies. In the breaker zone sand is rarely thrown into suspension. In the transition zone, sediment motion is largely by suspension with a period a little longer than the swell.

scholarly journals FIELD EXPERIMENTS ON LONGSHORE SAND TRANSPORT IN THE SURF ZONE

1982 ◽  
Vol 1 (18) ◽  
pp. 61 ◽  
Author(s):  
Nicholas C. Kraus ◽  
Masahiko Isobe ◽  
Hajime Igarashi ◽  
Tamio O. Sasaki ◽  
Kiyoshi Horikawa
Keyword(s):  
Current Velocity ◽  
Field Experiments ◽  
Surf Zone ◽  
Transport Rate ◽  
Sand Transport ◽  
Breaking Wave ◽  
Longshore Current ◽  
Mixing Depth ◽  
Sand Transport Rate ◽  
Advection Velocity

Eight fluorescent sand tracer experiments were performed in energetic surf zones on natural beaches and on beaches near structures to measure the short-term longshore sand transport rate. Tracer of up to four distinct colors was injected on a line crossing the surf zone to investigate the on-offshore distributions of the longshore sand adveetion velocity and transport rate. The tracer advection velocity, v , and the depth of mixing into the bed, b, were determined from large numbers of cores taken in situ throughout the sampling area. The sand advection velocity and mixing depth were not constant across the surf zone, but usually exhibited a maximum either toward the shoreline or toward the breaker line, or in both regions. The local breaking wave height, H. , and horizontal current velocity in the surf zone (yielding an average longshore current velocity V) were also measured. The data were interpreted with simple dimensional arguments to give the following results: b = 0.027 H,, v = 0.011 V, and the volumetric transport rate Q = 0.024 H V. Agreement was also found between the measured total longshore sand transport rate and a predictive expression due to Bagnold involving the breaking wave power and average longshore current velocity. Although the results appear reasonable and consistent, a problem remains concerning the apparent decrease in tracer advection speed alongshore recorded in most experiments at the longer sampling times.

Field Experiments on Longshore Sand Transport in the Surf Zone

1981 ◽  
Vol 24 (1) ◽  
pp. 171-194 ◽  
Author(s):  
Nicholas C. Kraus ◽  
Raymond S. Farinato ◽  
Kiyoshi Horikawa
Keyword(s):  
Field Experiments ◽  
Surf Zone ◽  
Sand Transport

scholarly journals DISTRIBUTION OF SEDIMENT TRANSPORT ACROSS THE SURF ZONE

1972 ◽  
Vol 1 (13) ◽  
pp. 52 ◽  
Author(s):  
Edward B. Thornton
Keyword(s):  
Sediment Transport ◽  
Surf Zone ◽  
Sand Transport ◽  
Bed Load ◽  
Relative Distribution ◽  
Longshore Current ◽  
Energy Principle ◽  
Load Transport ◽  
Bed Load Transport ◽  
Wave Induced

The wave-induced sand transport alongshore is investigated by an energy principle approach. Although the energy approach has been used before, this is the first application to comparing theory and measurements of the distribution of littoral transport along a line perpendicular to the beach. Bed load transport equations are formulated for outside and inside the surf zone. Sand transport data were collected in the field using bed load traps. Wave, tide, wind, and current information was collected simultaneously in order to verify the derived predictive equations for longshore current and sediment transport. Quite reasonable predictions are obtained for the relative distribution of bed load transport, both inside and outside the surf zone.

scholarly journals TOPOGRAPHIC CHANGES IN THE SURF ZONE PROFILE

1966 ◽  
Vol 1 (10) ◽  
pp. 30 ◽  
Author(s):  
Choule J. Sonu ◽  
Richard J. Russell
Keyword(s):  
North Carolina ◽  
Surf Zone ◽  
Three Dimensional ◽  
Vertical Plane ◽  
Normal Wave ◽  
Field Investigation ◽  
Dimensional Approach ◽  
Outer Banks ◽  
Plane Normal ◽  
The Waves

The conventional method of dealing with relationships between wave action and topographic response on a beach is to reduce the problem to a two-dimensional scheme that regards basic processes as taking place in a vertical plane normal to the shoreline. This scheme is valid only if the waves arrive at right angles to the shore and the nearshore contours are reasonably straight and parallel the beach. As these conditions are not realized in many cases another analytical method is necessary - one that recognizes effects of other than normal wave arrival and systematic patterns of diversification in nearshore topography. This study, based on a long period of field investigation on the Outer Banks, North Carolina, examines a three-dimensional approach. Observations from a long pier were used to explain nearshore topographic diversification and resulted in conclusions that were confirmed by subsequent field observation.

scholarly journals Waves and vortices in the inverse cascade regime of stratified turbulence with or without rotation

2016 ◽  
Vol 806 ◽  
pp. 165-204 ◽  
Author(s):  
Corentin Herbert ◽  
Raffaele Marino ◽  
Duane Rosenberg ◽  
Annick Pouquet
Keyword(s):  
Reynolds Number ◽  
Numerical Simulations ◽  
Direct Numerical Simulations ◽  
Vertical Shear ◽  
Energy Spectra ◽  
Stratified Turbulence ◽  
Viscous Effects ◽  
Inverse Cascade ◽  
Main Effects ◽  
The Waves

We study the partition of energy between waves and vortices in stratified turbulence, with or without rotation, for a variety of parameters, focusing on the behaviour of the waves and vortices in the inverse cascade of energy towards the large scales. To this end, we use direct numerical simulations in a cubic box at a Reynolds number $Re\approx 1000$, with the ratio between the Brunt–Väisälä frequency $N$ and the inertial frequency $f$ varying from $1/4$ to 20, together with a purely stratified run. The Froude number, measuring the strength of the stratification, varies within the range $0.02\leqslant Fr\leqslant 0.32$. We find that the inverse cascade is dominated by the slow quasi-geostrophic modes. Their energy spectra and fluxes exhibit characteristics of an inverse cascade, even though their energy is not conserved. Surprisingly, the slow vortices still dominate when the ratio $N/f$ increases, also in the stratified case, although less and less so. However, when $N/f$ increases, the inverse cascade of the slow modes becomes weaker and weaker, and it vanishes in the purely stratified case. We discuss how the disappearance of the inverse cascade of energy with increasing $N/f$ can be interpreted in terms of the waves and vortices, and identify the main effects that can explain this transition based on both inviscid invariants arguments and viscous effects due to vertical shear.

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