scholarly journals MODELING COARSE SAND TRANSPORT UNDER SKEWED OSCILLATORY FLOW USING A CFD-DEM APPROACH

2018 ◽  
pp. 18
Author(s):  
Yashar Rafati ◽  
Zhen Cheng ◽  
Xiao Yu ◽  
Tian-Jian Hsu ◽  
Joseph Calantoni
Keyword(s):  
Sediment Transport ◽  
Surf Zone ◽  
Regional Scale ◽  
Breaking Waves ◽  
Coarse Sand ◽  
Sand Transport ◽  
Sheet Flow ◽  
Two Phase ◽  
Coastal Morphology ◽  
Flow Transport

Onshore/offshore sediment transport in the nearshore is an important mechanism driving the evolution of coastal morphology. The so-called sheet flow is a transport regime, in which the flow forces are intense such that a large amount of transport occurs in a concentrated layer near the bed. Onshore transport is often associated with flow skewness/asymmetry. In the nearshore zone, due to the bottom slope and wave shoaling, the wave velocity tends be onshore skewed before breaking in the surf zone. For breaking waves, the velocity asymmetry (or acceleration skewness) may also play a key role in determining net sediment transport. Understanding the net sediment transport rate in response to wave skewness/asymmetry is fundamental to a better prediction of sediment transport in regional scale morphodynamic models. In this study, we used an Euler-Lagrange two-phase model to study sheet flow transport of coarse sand under oscillatory flows subject to velocity/acceleration skewness.

scholarly journals OBSERVATIONS OF HORIZONTAL AND VERTICAL SEDIMENT FLUXES ON A SANDBAR IN THE SUSPENDED AND SHEET FLOW LAYERS

2018 ◽  
pp. 30
Author(s):  
Ryan S. Mieras ◽  
Jack A. Puleo ◽  
Dylan Anderson ◽  
Daniel T. Cox ◽  
Tian-Jian Hsu ◽  
...  
Keyword(s):  
Sediment Transport ◽  
Surf Zone ◽  
Breaking Waves ◽  
Suspended Load ◽  
Bed Load ◽  
Sheet Flow ◽  
Coastal Morphology ◽  
Sediment Fluxes ◽  
Wave Forcing ◽  
Transport Component

The majority of prior sandbar migration studies have been conducted from the morphological standpoint, whereby, (i) bathymetric profiles are recorded over periods of time ranging from days to decades, at frequencies ranging from hourly to yearly (Ruessink et al., 2003), and (ii) hydrodynamic observations typically consist of far-field wave and environmental conditions. Subsequent modeling efforts have generally focused on tuning parameters in the sediment transport formulations (suspended load and bed load) to maximize model skill in predicting observed beach profiles over time (Fernández-Mora et al., 2015; Hoefel and Elgar, 2003). However, little emphasis at the operational level has been placed on tuning coastal morphology models to the true relative contributions of the physical processes (e.g. suspended load, bed load and/or sheet flow) that drive the changing bathymetry. This is due, in part, to the lack of detailed sediment transport observations (field and lab) under realistic wave forcing conditions and spatially variable bathymetry. Such a modeling approach leads to the improper quantification (magnitude and/or direction) of each modeled sediment transport component under skewed-asymmetric and/or breaking waves, often observed in the surf zone. The present study aims to better understand the physical mechanisms responsible for driving cross-shore sediment transport over a sandbar by quantifying (a) the vertical exchange of sediment at the near-bed interface (i.e. pick-up layer), and (b) intra-wave horizontal sediment fluxes in the suspended load and sheet layers.

Application of remote sensing technology to the relation of submarine pipelines and coastal morphology

1995 ◽  
Vol 32 (2) ◽  
pp. 77-83
Author(s):  
Y. Yüksel ◽  
D. Maktav ◽  
S. Kapdasli
Keyword(s):  
Remote Sensing ◽  
Sediment Transport ◽  
Surf Zone ◽  
Hydrodynamic Forces ◽  
Construction Site ◽  
Coastal Morphology ◽  
Remote Sensing Technology ◽  
Sensing Technology ◽  
Sea Bed

Submarine pipelines must be designed to resist wave and current induced hydrodynamic forces especially in and near the surf zone. They are buried as protection against forces in the surf zone, however this procedure is not always feasible particularly on a movable sea bed. For this reason the characteristics of the sediment transport on the construction site of beaches should be investigated. In this investigation, the application of the remote sensing method is introduced in order to determine and observe the coastal morphology, so that submarine pipelines may be protected against undesirable seabed movement.

A two-phase approach to wave-induced sediment transport under sheet flow conditions

2011 ◽  
Vol 58 (11) ◽  
pp. 1072-1088 ◽  
Author(s):  
Xin Chen ◽  
Yong Li ◽  
Xiaojing Niu ◽  
Daoyi Chen ◽  
Xiping Yu
Keyword(s):  
Sediment Transport ◽  
Flow Conditions ◽  
Sheet Flow ◽  
Two Phase ◽  
Phase Approach ◽  
Wave Induced

Two-phase hydrodynamic and sediment transport modeling of wave-generated sheet flow

2009 ◽  
Vol 32 (8) ◽  
pp. 1267-1283 ◽  
Author(s):  
R. Bakhtyar ◽  
A. Yeganeh-Bakhtiary ◽  
D.A. Barry ◽  
A. Ghaheri
Keyword(s):  
Sediment Transport ◽  
Transport Modeling ◽  
Sheet Flow ◽  
Two Phase

scholarly journals SYNOPTIC OBSERVATIONS OF SAND MOVEMENT

1970 ◽  
Vol 1 (12) ◽  
pp. 49
Author(s):  
David B. Duane
Keyword(s):  
Sediment Transport ◽  
Los Angeles ◽  
Surf Zone ◽  
Atomic Energy Commission ◽  
National Laboratory ◽  
Breaking Waves ◽  
Army Corps ◽  
Corps Of Engineers ◽  
Oak Ridge ◽  
Synoptic Observations

The U S Army Corps of Engineers' Coastal Engineering Research Center, in cooperation with the Atomic Energy Commission, initiated a multi-agency program to create a viable radioisotopic sand tracing (RIST) program Other agency participants in this program have been the Los Angeles District, Corps of Engineers, U S Air Force (First Strategic Aerospace Division), U S Navy (Pacific Missile Range), U S Army Mobility Equipment Command, National Aeronautics and Space Administration, and the State of California (Dept of Navigation and Ocean Development) CERC, together with the AEC's Oak Ridge National Laboratory has developed tagging procedures, hardware development, field surveys and data handling techniques that permit collection and analysis of over 12,000 bits of information per hour over a survey track of approximately 18,000 feet Data obtained with the RIST system can be considered as nearly synoptic observations of sediment transport m a single environmental zone or in adjacent beach, surf and offshore zones Using sand tagged with isotopes of gold, experiments have been carried out at several sites on the California coast Surf, Point Conception area, Point Mugu, and Oceanside Data from the studies carried out in beach areas unmodified by littoral barriers indicate that under a given set of wave conditions the alongshore velocity of sediment transport differs from zone to zone such that transport seaward of peakmg-breaking waves < transport on the beach face < transport in the plunge and surf zone Because of these differences, tracing surveys confined solely to the foreshore or offshore zones produce data only partially indicative of transport in the zone of immediate concern to coastal engineers.

scholarly journals VALIDATION OF A BUOYANCY-MODIFIED TURBULENCE MODEL BY NUMERICAL SIMULATIONS OF BREAKING WAVES OVER A FIXED BAR

2018 ◽  
pp. 71
Author(s):  
Brecht Devolder ◽  
Peter Troch ◽  
Pieter Rauwoens
Keyword(s):  
Numerical Simulations ◽  
Wave Breaking ◽  
Surf Zone ◽  
Breaking Waves ◽  
Navier Stokes ◽  
Two Phase ◽  
Numerical Wave Flume ◽  
Wave Flume ◽  
Nearshore Sediment Transport ◽  
Run Up

The surf zone dynamics are governed by important processes such as turbulence generation , nearshore sediment transport , wave run-up and wave overtopping at a coastal structure. During field observations , it is very challenging to measure and quantify wave breaking turbulence . Complementary to experimental laboratory studies in a more controlled environment , numerical simulations are highly suitable to understand and quantify surf zone processes more accurately. In this study, wave propagation and wave breaking over a fixed barred beach profile is investigated using a two­ phase Navier-Stokes flow solver. We show that accurate predictions of the turbulent two-phase flow field require special attention regarding turbulence modelling. The numerical wave flume is implemented in the open­ source OpenFOAM library. The computed results (surface elevations , velocity profiles and turbulence levels) are compared against experimental measurements in a wave flume (van der A et al., 2017) .

scholarly journals ONSHORE-OFFSHORE TRANSPORT AND BEACH PROFILE CHANGE

1980 ◽  
Vol 1 (17) ◽  
pp. 71 ◽  
Author(s):  
Masataro Hattori ◽  
Ryoichi Kawamata
Keyword(s):  
Gravitational Force ◽  
Surf Zone ◽  
Breaking Waves ◽  
Time Parameter ◽  
Sand Transport ◽  
Bottom Slope ◽  
Beach Profile ◽  
Physical Consideration ◽  
Offshore Transport ◽  
Profile Change

In this paper a model is presented to describe onshore-offshore sand transport in the surf zone. The model is based on the physical consideration that when the net transport attains a state of equilibrium, the power expended through gravitational force in suspending sand grains is balanced by that due to the uplifting force arising from the turbulence generated by breaking waves. Two important parameters controlling sand transport are the dimensionless fall-time parameter and bottom slope.

scholarly journals DISTRIBUTION OF SAND TRANSPORT RATE ACROSS A SURF ZONE

1978 ◽  
Vol 1 (16) ◽  
pp. 95 ◽  
Author(s):  
Toru Swaragi ◽  
Ichiro Deguchi
Keyword(s):  
Shear Stress ◽  
Sediment Transport ◽  
Surf Zone ◽  
Transport Rate ◽  
Sand Transport ◽  
Shear Stresses ◽  
Bottom Shear Stress ◽  
Longshore Current ◽  
Unidirectional Flow ◽  
Longshore Sediment Transport

The distributions of longshore and on-offshore sediment transport rates in a surf zone were measured by an apparatus which was able to separately record both components of the sediment transport rate,, The characteristics of their distributions were discussed from the bottom shear stresses which were measured by the shear meter under the same wave conditions as the laboratory experiment of the sediment transport. The maximum bottom shear stress took place at the depth between the breaking depth of waves and the depth where the velocity of the longshore current showed a maximum. On the other hand, the maximum on-offshore and longshore sediment transport rates occured at the depth slightly shallower than the depth where the maximum bottom shear stress took place. What's more, the longshore sediment transport rates were represented by the longshore current velocity and the bottom shear stress generated by waves and the longshore current. However, the distribution of the on-offshore sediment transport rates showed more complicated profile than that of the longshore sediment transport rates because there were no eminent unidirectional flow in the direction normal to the shore line. Therefore, the on-offshore sediment transport rates could not be formulated by the bottom shear stresses.

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