scholarly journals NUMERICAL AND EXPERIMENTAL DESCRIPTION OF THE FLOW, BOUNDARY LAYER AND BED EVOLUTION IN BORE-DRIVEN SWASH ON A COARSE SEDIMENT BEACH

2012 ◽  
Vol 1 (33) ◽  
pp. 33 ◽  
Author(s):  
Riccardo Briganti ◽  
Nicholas Dodd ◽  
Dubravka Pokrajac ◽  
Tom O'Donoghue
Keyword(s):  
Sediment Transport ◽  
Shallow Water Equations ◽  
Swash Zone ◽  
Coupled Numerical Model ◽  
Stress Prediction ◽  
Bed Evolution ◽  
Run Up ◽  
Momentum Integral ◽  
The University ◽  
Fully Coupled

The paper presents the results of a comparison between a fully coupled numerical model for the hydro- and morphodynamics of the swash zone. The model solves simultaneously the Non-Linear Shallow Water Equations and the Exner equation for the bed updates. The model uses the simple Grass formula for the sediment transport and the momentum integral method for the bottom shear stress prediction. The laboratory tests were carried out at the University of Aberdeen swash facility and aimed at studying the hydrodynamics and sediment transport of a single, bore-generated swash event. The comparison is carried out in terms of water depth and horizontal velocity (depth average and profiles) and sediment transport. The model performs well in predicting these quantities, above all during the run-up.

Beach-face evolution in the swash zone

2010 ◽  
Vol 661 ◽  
pp. 316-340 ◽  
Author(s):  
DAVID MATTHEW KELLY ◽  
NICK DODD
Keyword(s):  
Sediment Transport ◽  
Swash Zone ◽  
Full Coupling ◽  
Bed Evolution ◽  
Run Up ◽  
The One ◽  
Offshore Transport ◽  
Bed Mobility ◽  
Upper Third ◽  
Fully Coupled

We investigate swash on an erodible beach using the one-dimensional shallow-water equations fully coupled to a bed-evolution (Exner) equation. In particular, the dam-break/bore-collapse initial condition of Shen & Meyer (J. Fluid Mech., vol. 16, 1963, pp. 113–125) and Peregrine & Williams (J. Fluid Mech., vol. 440, 2001, pp. 391–399) is investigated using a numerical model based on the method of characteristics. A sediment-transport formula (cubic in velocity u: Au3) is used here; this belongs to a family of sediment-transport formulae for which Pritchard & Hogg (Coastal Engng, vol. 52, 2005, pp. 1–23) showed that net sediment transport under the Shen & Meyer (1963) bore collapse is offshore throughout the swash zone when a non-erodible bed is considered. It is found that full coupling with the beach, although still resulting in the net offshore transport of sediment throughout the swash zone, leads to a large reduction in the net offshore transport of sediment from the beach face. This is particularly true for the upper third of the swash zone. Moreover, in contradistinction to swash flows over non-erodible beds, flows over erodible beaches are unique to the bed mobility and porosity under consideration; this has very important implications for run-up predictions. The conclusion is that it is essential to consider full coupling of water and bed motions (i.e. full morphodynamics) in order to understand and predict sediment transport in the swash, regardless of other physical effects (e.g. turbulence, infiltration, pre-suspended sediment, etc.).

scholarly journals Modeling swash zone sediment transport at Truc Vert Beach

2012 ◽  
Vol 1 (33) ◽  
pp. 105 ◽  
Author(s):  
Arnold Van Rooijen ◽  
Ad Reniers ◽  
Jaap Van Thiel de Vries ◽  
Chris Blenkinsopp ◽  
Robert McCall
Keyword(s):  
Sediment Transport ◽  
Shallow Water ◽  
Water Level ◽  
Morphological Change ◽  
Shallow Water Equations ◽  
Transport Model ◽  
Early Spring ◽  
Swash Zone ◽  
One Dimensional ◽  
Run Up

A one-dimensional hydrostatic version of the XBeach model (Roelvink et al., 2009) is applied to hindcast swash morphodynamics measured during an accretive, and an erosive tide at Le Truc Vert beach (France) in early spring 2008 (Masselink et. al, 2009; Blenkinsopp et al., 2011). Swash hydrodynamics are solved by applying the nonlinear shallow water equations, and sediment transport rates are obtained from a combined intra-wave Nielsen and Bagnold type transport model. Reasonable predictions of morphological change in the swash were obtained. Nevertheless, the model underpredicts the water level setup and/or wave run-up during the accretive tide, which is hypothesized to be related to 2D-effects.

scholarly journals An experimental study on sediment transport and bed evolution under different swash zone morphological conditions

2012 ◽  
Vol 68 ◽  
pp. 31-43 ◽  
Author(s):  
José M. Alsina ◽  
Iván Cáceres ◽  
Maurizio Brocchini ◽  
Tom E. Baldock
Keyword(s):  
Experimental Study ◽  
Sediment Transport ◽  
Swash Zone ◽  
Bed Evolution

scholarly journals NUMERICAL STUDY ON THE INFLUENCE OF INFILTRATION ON SWASH HYDRODYNAMICS AND SEDIMENT TRANSPORT IN THE SWASH ZONE

2017 ◽  
pp. 3
Author(s):  
Alejandro M. Hammeken ◽  
Richard R. Simons
Keyword(s):  
Sediment Transport ◽  
Numerical Study ◽  
Navier Stokes ◽  
Shear Stresses ◽  
Swash Zone ◽  
Depth Data ◽  
Run Up ◽  
Opposing Effects ◽  
Phase Stresses ◽  
Bed Shear Stresses

Infiltration and exfiltration processes have a significant influence on the hydrodynamics of the swash zone. Such processes need to be taken into account in the modelling of cross-shore sediment transport and the prediction of beach profile evolution. This paper presents a numerical study of the swash hydrodynamics using a 2D Volume-Averaged Reynolds-Averaged Navier-Stokes model, which was calibrated and validated against new experimental data. The model was used to simulate wave run-up from regular waves over permeable and impermeable fixed slopes. Swash flow velocities and water depth data were obtained from the simulations and used to estimate bed shear stresses at three different locations on the beach slope. The results show that infiltration can have opposing effects on the bed shear stress when compared to equivalent swash on an impermeable slope. During the uprush phase, stresses are directly increased due to boundary layer thinning, whereas, during the backwash phase, there is a significant reduction of flow leading to a decrease in the bed shear stresses.

scholarly journals Evaluation of the Applicability of STIV to Wave Characteristic Measurement in the Swash Zone

2021 ◽  
Vol 8 (3) ◽  
pp. 141-150
Author(s):  
Yeon-Joong Kim ◽  
Jong-Sung Yoon ◽  
Makoto Hasegawa ◽  
Jae-Hoon Jeong
Keyword(s):  
Sediment Transport ◽  
Turbulent Flow ◽  
Flow Velocity ◽  
Flow Characteristics ◽  
Surface Velocity ◽  
Swash Zone ◽  
Movement Velocity ◽  
Image Velocimetry ◽  
Run Up ◽  
Short Time

The swash zone is an area that causes a change in the shape of a beach by generating sediment transport under the influence of intermittent waves, where wave run-up and run-down are infinitely repeated in the final stage of the shoaling process. However, the ability to predict the sediment transport is extremely poor despite the swash zone being an extremely important area in terms of offshore disaster prevention. In particular, many researchers are conducting studies on the development of various types of observation equipment and analysis techniques because the turbulent flow of active fluid dominates the sediment transport and is an extremely important parameter for the analysis of the transport mechanism. However, in flow velocity measurement, it is difficult to measure a quantitative representative flow velocity over time because the swash zone has a shallow water depth and an active turbulent flow. Expensive equipment and short-time measurement are also limitations. Therefore, the purpose of this study was to evaluate the applicability of nonintrusive space-time image velocimetry(STIV) to analyze the flow characteristics of fluid in the swash zone, such as the movement velocity and period of intermittent waves in the shoaling process. The prediction accuracy was improved by removing various noises included in the images with the introduction of artificial intelligence for immediate and accurate calculation of the representative flow velocity using images that can be obtained easily. Consequently, it was discovered that the spatial representative flow velocity occurring in the swash zone, change in the wave period according to the shoaling effect, rip current and surface velocity can be measured.

scholarly journals The influence of wave groups and wave-swash interactions on sediment transport and bed evolution in the swash zone

2018 ◽  
Vol 140 ◽  
pp. 23-42 ◽  
Author(s):  
José M. Alsina ◽  
Joep van der Zanden ◽  
Iván Cáceres ◽  
Jan S. Ribberink
Keyword(s):  
Sediment Transport ◽  
Swash Zone ◽  
Wave Groups ◽  
Bed Evolution

Numerical Investigation of Wave Period Influence on Long Wave Run-Up on Slope With Rigid Vegetation

2016 ◽  
Author(s):  
Jun Tang ◽  
Yongming Shen
Keyword(s):  
Shallow Water Equations ◽  
Water Wave ◽  
Wave Period ◽  
Coastal Vegetation ◽  
Coastal Structures ◽  
Rigid Vegetation ◽  
Comparison With Experiment ◽  
Long Wave ◽  
Nonlinear Shallow Water Equations ◽  
Run Up

Coastal vegetation can not only provide shade to coastal structures but also reduce wave run-up. Study of long water wave climb on vegetation beach is fundamental to understanding that how wave run-up may be reduced by planted vegetation along coastline. The present study investigates wave period influence on long wave run-up on a partially-vegetated plane slope via numerical simulation. The numerical model is based on an implementation of Morison’s formulation for rigid structures induced inertia and drag stresses in the nonlinear shallow water equations. The numerical scheme is validated by comparison with experiment results. The model is then applied to investigate long wave with diverse periods propagating and run-up on a partially-vegetated 1:20 plane slope, and the sensitivity of run-up to wave period is investigated based on the numerical results.

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