scholarly journals EXPERIMENTAL AND NUMERICAL STUDIES ON WAVE PROPAGATION OVER COARSE GRAINED SLOPING BEACH

2011 ◽  
Vol 1 (32) ◽  
pp. 26 ◽  
Author(s):  
Tai-Wen Hsu ◽  
Jian-Wu Lai ◽  
Yuan-Jyh Lan
Keyword(s):  
Wave Propagation ◽  
Velocity Field ◽  
Porous Layer ◽  
Surf Zone ◽  
Three Dimensional ◽  
Coarse Grained ◽  
Swash Zone ◽  
Sloping Bed ◽  
Sloping Beach ◽  
Three Dimensional Simulations

In this paper, the hydrodynamics and turbulence on wave propagation over coarse grained sloping beach is investigated by both experimental and numerical methods. The coarse grained sloping beach was conducted over a 1:5 smooth inclined bottom with two layers of spherical balls. A set of newly and rarely experimental data for the distribution and evolution of the wave and velocity field over porous sloping beach were measured in this study. The particle image velocimetry (PIV) and digital image process (DIP) techniques are employed to measure the flow field and free surface both inside and outside regions for a coarse grain porous sloping bed. Eleven fields of views (FOVs) were integrated to represent the global results converting the entire propagating waves from the outer to the inner surf zones and swash zones. In addition, a high-resolution CCD Camera was constructed to capture wave propagating images continuously. Subsequent digital image processing (DIP) techniques that including image enhancement, coordinate transformation, edge detection and sub-pixel concept for resolution advancement were developed to analysis the image and get the information of wave motions. In this experimental study, the PIV and DIP techniques offer a possibility for measuring full scale spatio-temporal information of the wave motions and velocity field within / without the porous sloping bed without instructive instrument. Furthermore, the FLOW-3D which based on the Navier-Stokes equations was adopted for CFD computations. The direct three-dimensional simulations were employed for simulating wave profile and velocity field for the sloping beach. Numerical results were favorably compared with experiments to examine the validity of the model. According to the comparison of the wave and velocity data of hydraulic physical model with computational results, the direct three-dimensional simulations method can offer results much agreement with the experimental data in the global regions. The results showed that direct three-dimensional simulations can resolve the wave and velocity profile more complete and reasonable descriptions from outer to the inner porous layer and it is true no matter in the surf zone, swash zone and within the porous layer. Moreover, according to the experimental analysis, the process of the turbulence characteristics of the maximum turbulent kinetic energy, turbulent kinetic energy dissipation rate and turbulence intensity occurred between the toe of breaker and surface of porous layer. In addition, general discussion of hydrodynamics and turbulence on wave propagation over coarse grained sloping beach and impermeable sloping bed were investigated with the results of direct three-dimensional simulations in this study. The results showed that wave propagation over coarse grained sloping beach effects the breaker types in the shallow water, i.e. the steepening and overturning of the front face due to plunging breaker over impermeable sloping beach becomes indistinctively and the breaker type transform into the collapsing type. Besides, the dissipation of wave energy due to the role of infiltration and friction are significant differences from surf zone to swash zone between the coarse grained and impermeable sloping beach.

scholarly journals Nonlinear waves and nearshore currents over variable bathymetry in curve-shaped coastal areas

2019 ◽  
Vol 5 (4) ◽  
pp. 419-431 ◽  
Author(s):  
Francesco Gallerano ◽  
Giovanni Cannata ◽  
Federica Palleschi
Keyword(s):  
Wave Propagation ◽  
Surf Zone ◽  
Stokes Equations ◽  
Three Dimensional ◽  
Nonlinear Effects ◽  
Coastal Areas ◽  
Navier Stokes ◽  
Swash Zone ◽  
Navier Stokes Equations ◽  
Nearshore Currents

AbstractIrregular coastlines and variable bathymetry produce nonlinear effects on wave propagation which play a significant role on the formation of nearshore currents. To protect the coastline from the erosional action of nearshore currents, it is usual to adopt coastal defence works such as submerged breakwaters. If properly designed, they give rise to circulation patterns capable to induce sedimentation of suspended material at the nearshore region. To numerically simulate the hydrodynamic effects of submerged breakwaters in irregular coastal areas, we use a numerical model which is based on an integral contravariant formulation of the three-dimensional Navier–Stokes equations in a time-dependent coordinate system. These equations are numerically solved by a non-hydrostatic shock-capturing numerical scheme which is able to simulate the wave propagation from deep water to the shoreline, including the surf zone and swash zone.

scholarly journals INTEGRATED STUDY ON THE VELOCITY FIELD INDUCED BY PLUNGING BREAKERS

2012 ◽  
Vol 1 (33) ◽  
pp. 27
Author(s):  
Germán Daniel Rivillas ◽  
Adrián Pedrozo-Acuña ◽  
Rodolfo Silva ◽  
Alec Torres-Freyermuth ◽  
Cesar Gutierrez
Keyword(s):  
Velocity Field ◽  
Numerical Model ◽  
Surf Zone ◽  
Velocity Fields ◽  
Acoustic Doppler Velocimeter ◽  
Swash Zone ◽  
Aerated Flow ◽  
Offshore Flow ◽  
Flow Propagation ◽  
Integrated Study

In this investigation we employ a technique called Bubble Image Velocimeter (BIV) to obtain measurements of flow fields in the surf-zone. This technique allows measurements of flow velocity in the aerated breaking zone, where other techniques are ineffective. The technique has been widely used to study flow propagation in front of vertical structures, it is employed in this study to estimate the velocity field induced by the propagation of a plunging wave travelling over an impermeable slope. The BIV measurements were compared to those obtained with an Acoustic Doppler Velocimeter (ADV) showing that the BIV technique is more suitable when the velocity field is estimated under the presence of an aerated flow. Moreover, the phase-averaged velocity fields obtained from the numerical model were compared against those evaluated from the BIV measurements. A reliable estimation of the VOF-type numerical derivations in the surf zone was established. In the swash zone, an over prediction of the offshore flow was identified.

A particle image velocimetry investigation on laboratory surf-zone breaking waves over a sloping beach

2007 ◽  
Vol 588 ◽  
pp. 353-397 ◽  
Author(s):  
O. KIMMOUN ◽  
H. BRANGER
Keyword(s):  
Particle Image Velocimetry ◽  
Velocity Field ◽  
Water Waves ◽  
Particle Image ◽  
Surf Zone ◽  
Wave Transformation ◽  
Time Step ◽  
Complete Space ◽  
Image Velocimetry ◽  
Sloping Beach

Particle image velocimetry (PIV) measurements were performed in a wave tank under water waves propagating and breaking on a 1/15 sloping beach. The wave transformation occurred in the surf zone over a large domain covering several wavelengths from incipient breaking to swash zone beyond the shoreline. PIV spatial interrogation windows must be small enough to obtain accurate velocities, and one window covers only a small part of the domain. To overcome this problem and to measure the instantaneous velocity field over the whole surf zone area, we have split the full field into 14 overlapping smaller windows of the same size. Local measurements were synchronized with each other using pulsed TTL triggers and wave gauge data. The full velocity field was then reconstructed at every time step by gathering the 14 PIV fields. We then measured the complete space–time evolution of the velocity field over the whole surf zone. We determined also the ensemble-period-average and phase-average components of the flow with their associated fluctuating parts. We used the PIV images and velocity measurements to estimate the void fraction in each point of the surf zone. Special attention was given to the calculation of the spatial derivatives in order to obtain relevant information on vorticity and on the physical terms that appear in the fluctuating kinetic energy transport equation.

scholarly journals QUASI-3D MODELLING OF SURF ZONE DYNAMICS

2011 ◽  
Vol 1 (32) ◽  
pp. 52
Author(s):  
Arjen Luijendijk ◽  
Johan Henrotte ◽  
Dirk Jan Walstra ◽  
Maarten Van Ormondt
Keyword(s):  
Flow Model ◽  
Surf Zone ◽  
Three Dimensional ◽  
3D Modelling ◽  
Dimensional Model ◽  
Computationally Efficient ◽  
Three Dimensional Model ◽  
3D Effects ◽  
The Vertical Distribution ◽  
Three Dimensional Simulations

A quasi-three-dimensional model (quasi-3D) has been developed through the implementation of an analytical 1DV flow model in existing depth-averaged shallow water equations. The model includes the effects of waves and wind on the vertical distribution of the horizontal velocities. Comparisons with data from both physical and field cases show that the quasi-3D approach is able to combine the effect of vertical structures with the efficiency of depth-averaged simulations. Inter-comparisons with three-dimensional simulations show that the quasi-3D approach can represent similar velocity profiles in the surf zone. Quasi-3D morphodynamic simulations show that the bed dynamics in the surf zone represent the relevant 3D effects in the surf zone much more than the depth-averaged computations. It was shown that the quasi-3D approach is computationally efficient as it only adds about 15-20% to the runtimes of a 2DH simulation which is minor compared to a run time increase of 250-800% when switching to a 3D simulation.

The coastal refraction-diffraction wave propagation model

1995 ◽  
Vol 17 (4) ◽  
pp. 6-12
Author(s):  
Nguyen Tien Dat ◽  
Dinh Van Manh ◽  
Nguyen Minh Son
Keyword(s):  
Wave Propagation ◽  
Field Data ◽  
Surf Zone ◽  
Propagation Model ◽  
Wave Transformation ◽  
Diffraction Effect ◽  
Linear Wave ◽  
Diffraction Wave ◽  
Linear Wave Propagation ◽  
Wave Propagation Model

A mathematical model on linear wave propagation toward shore is chosen and corresponding software is built. The wave transformation outside and inside the surf zone is considered including the diffraction effect. The model is tested by laboratory and field data and gave reasonables results.

Application of an Element-free Galerkin Method to Water Wave Propagation Problems

2014 ◽  
Vol 60 (1-4) ◽  
pp. 87-105 ◽  
Author(s):  
Ryszard Staroszczyk
Keyword(s):  
Wave Propagation ◽  
Galerkin Method ◽  
Present Model ◽  
Free Surface Elevation ◽  
Element Free Galerkin Method ◽  
Plane Flow ◽  
Element Free Galerkin ◽  
Proposed Model ◽  
Sloping Bed ◽  
Element Free

Abstract The paper is concerned with the problem of gravitational wave propagation in water of variable depth. The problem is solved numerically by applying an element-free Galerkin method. First, the proposed model is validated by comparing its predictions with experimental data for the plane flow in water of uniform depth. Then, as illustrations, results of numerical simulations performed for plane gravity waves propagating through a region with a sloping bed are presented. These results show the evolution of the free-surface elevation, displaying progressive steepening of the wave over the sloping bed, followed by its attenuation in a region of uniform depth. In addition, some of the results of the present model are compared with those obtained earlier by using the conventional finite element method.

Numerical study of the flow of a mixture of reacting gases in an inhomogeneous catalyst layer

2003 ◽  
Vol 3 ◽  
pp. 246-254
Author(s):  
C.I. Mikhaylenko ◽  
S.F. Urmancheev
Keyword(s):  
Velocity Field ◽  
Chemical Reactions ◽  
Porous Layer ◽  
Computational Experiment ◽  
Numerical Study ◽  
Fluid Velocity ◽  
Catalyst Layer ◽  
Granular Catalyst ◽  
Fluid Velocity Field

The behavior of a liquid flowing through a fixed bulk porous layer of a granular catalyst is considered. The effects of the nonuniformity of the fluid velocity field, which arise when the surface of the layer is curved, and the effect of the resulting inhomogeneity on the speed and nature of the course of chemical reactions are investigated by the methods of a computational experiment.

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