3D Wave Transformation Through Openings in Coastal Structures

2013 ◽  
Author(s):  
Vasiliki Katsardi ◽  
Vasiliki K. Tsoukala ◽  
Kostas A. Belibassakis
Keyword(s):  
Wave Propagation ◽  
Numerical Solution ◽  
Water Depth ◽  
Harmonic Wave ◽  
Wave Transformation ◽  
Wave Flow ◽  
Finite Width ◽  
Coastal Structures ◽  
Diffraction Effects ◽  
Incident Waves

Standard openings in coastal structures are the flushing culverts at breakwaters, allowing periodic exchange of the harbor basin water leading to improved water quality. These openings involve sudden water depth changes occurring when the incident waves meet these openings and transmitted into the harbour. The wave transformations during wave propagation through flushing culverts are dominated by 3D diffraction effects due to sudden water depth changes, along with the finite width of the culvert. A new coupled-mode model, based on eigenfunctions expansions of the Laplace equation, is developed and applied to the numerical solution of the local 3D wave flow problem at the opening. The harmonic wave field is excited by incident parallel waves. The numerical solution converges rapidly, permitting the series truncation at its first terms. The proposed method fully accounts for the 3D diffraction effects and produces information to couple with mild-slope models describing efficiently wave propagation and transformation in coastal regions.

scholarly journals MODELLING WAVE TRANSFORMATION ACROSS A FRINGING REEF USING SWASH

2012 ◽  
Vol 1 (33) ◽  
pp. 26 ◽  
Author(s):  
Marcel Zijlema
Keyword(s):  
Wave Propagation ◽  
Coral Reef ◽  
Wave Breaking ◽  
Flow Model ◽  
Wave Transformation ◽  
Wave Flow ◽  
Infragravity Waves ◽  
Fringing Reef ◽  
Wave Induced ◽  
Steep Slopes

This paper presents the application of the open source non-hydrostatic wave-flow model SWASH to wave propagation over a fringing reef, and the results are discussed and compared with observations obtained from a laboratory experiment subjected to various incident wave conditions. This study focus not only on wave breaking, bottom friction, and wave-induced setup and runup, but also on the generation and propagation of infragravity waves beyond the reef crest. Present simulations demonstrate the overall predictive capabilities of the model for a typical coral reef with steep slopes and extended reef flats.

scholarly journals CHRONIC BEACH EROSION INDUCED BY COASTAL STRUCTURES IN CHELEM, YUCATÁN

2012 ◽  
Vol 1 (33) ◽  
pp. 125 ◽  
Author(s):  
María Alejandra Lira-Pantoja ◽  
Alec Torres-Freyermuth ◽  
Christian Mario Appendini ◽  
Diana Carolina Fernández ◽  
Paulo Salles ◽  
...  
Keyword(s):  
Sediment Transport ◽  
Numerical Model ◽  
Water Depth ◽  
Beach Erosion ◽  
Wave Transformation ◽  
Coastal Structures ◽  
Erosion Rates ◽  
Wave Conditions ◽  
Alongshore Sediment Transport ◽  
The Waves

The Yucatan coastline has been experiencing beach erosion during the past few decades; the erosion has reached critical points at some locations such as the Chelem beach, located near the Progreso Pier. Despite this problem, only few studies have been devoted in order to investigate the role of coastal structures on explaining the high erosion rates reported at this location. Therefore, the aim of this work is to evaluate the effects of the Progreso Pier on the wave transformation and alongshore sediment transport in the study area. Field surveys were conducted in a monthly basis in order to estimate the erosion rates and wave conditions with an ADCP installed at 8 m water depth. The field information confirmed the high erosional trends (O(1)m/year) that explain coastal infrastructure damage and property losses. The wave measurements were employed as the forcing of a wind-wave numerical model (MIKE 21 SW). The numerical model is implemented in the study area for two different scenarios, with and without the pier; this was to estimate nearshore wave conditions. Subsequently, the nearshore wave climate at 5 m water depth is employed for the calculation of alongshore sediment transport rates in 5 points that are representative of the littoral drift along the study area. The modeling results show that the pier acts as a large scale wave-sheltering structure that induces important alongshore sediment transport gradients under mean wave conditions, decreasing the capacity of the waves to recover the beach. On the other hand, during winter storms, when the direction of the waves is from the NNW, the structure does not seem to play an important role on wave transformation into the study. As a result, the Progreso Pier enhances beach erosion in the Chelem area by inducing algonshore gradients in sediment transport and decreasing the beach recovery capability

Comparison of the performance of oscillating water column devices based on arrangements of water columns

2020 ◽  
Vol 14 (3) ◽  
pp. 7082-7093
Author(s):  
Jahirwan Ut Jasron ◽  
Sudjito Soeparmani ◽  
Lilis Yuliati ◽  
Djarot B. Darmadi
Keyword(s):  
Wave Propagation ◽  
Water Column ◽  
Water Depth ◽  
Graphical Form ◽  
Wave Power ◽  
Oscillating Water Column ◽  
Power Absorption ◽  
Water Columns ◽  
Single Column ◽  
Parallel Arrangement

The hydrodynamic performance of oscillating water column (OWC) depends on the depth of the water, the size of the water column and its arrangement, which affects the oscillation of the water surface in the column. An experimental method was conducted by testing 4 water depths with wave periods of 1-3 s. All data recorded by the sensor is then processed and presented in graphical form. The research focused on analyzing the difference in wave power absorption capabilities of the three geometric types of OWC based on arrangements of water columns. The OWC devices designed as single water column, the double water column in a series arrangement which was perpendicular to the direction of wave propagation, and double water column in which the arrangement of columns was parallel to the direction of wave propagation. This paper discussed several factors affecting the amount of power absorbed by the device. The factors are the ratio of water depth in its relation to wavelength (kh) and the inlet openings ratio (c/h) of the devices. The test results show that if the water depth increases in the range of kh 0.7 to 0.9, then the performance of the double chamber oscillating water column (DCOWC) device is better than the single chamber oscillating water column (SCOWC) device with maximum efficiency for the parallel arrangement 22,4%, series arrangement 20.8% and single column 20.7%. However, when referring to c/h, the maximum energy absorption efficiency for a single column is 27.7%, double column series arrangement is 23.2%, and double column parallel arrangement is 29.5%. Based on the results of the analysis, DCOWC devices in parallel arrangement showed the ability to absorb better wave power in a broader range of wave frequencies. The best wave of power absorption in the three testing models occurred in the wave period T = 1.3 seconds.

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.

Boundary conditions for the numerical solution of wave propagation problems

Geophysics ◽  
1978 ◽  
Vol 43 (6) ◽  
pp. 1099-1110 ◽  
Author(s):  
Albert C. Reynolds
Keyword(s):  
Wave Propagation ◽  
Reflection Coefficient ◽  
Finite Difference ◽  
Boundary Conditions ◽  
Numerical Solution ◽  
Neumann Boundary ◽  
Synthetic Seismograms ◽  
Neumann Boundary Conditions ◽  
Numerical Calculations ◽  
Reflection Coefficients

Many finite difference models in use for generating synthetic seismograms produce unwanted reflections from the edges of the model due to the use of Dirichlet or Neumann boundary conditions. In this paper we develop boundary conditions which greatly reduce this edge reflection. A reflection coefficient analysis is given which indicates that, for the specified boundary conditions, smaller reflection coefficients than those obtained for Dirichlet or Neumann boundary conditions are obtained. Numerical calculations support this conclusion.

Wave Propagation in Two-Dimensional Nonlinear Periodic Lattices

2009 ◽  
Author(s):  
Raj K. Narisetti ◽  
Massimo Ruzzene ◽  
Michael J. Leamy
Keyword(s):  
Wave Propagation ◽  
Linear Models ◽  
Periodic Structures ◽  
Harmonic Wave ◽  
Excitation Amplitude ◽  
Pass Band ◽  
Perturbation Approach ◽  
Nonlinear Stiffness ◽  
Two Dimensional ◽  
Low Amplitude

This paper investigates wave propagation in two-dimensional nonlinear periodic structures subject to point harmonic forcing. The infinite lattice is modeled as a springmass system consisting of linear and cubic-nonlinear stiffness. The effects of nonlinearity on harmonic wave propagation are analytically predicted using a novel perturbation approach. Response is characterized by group velocity contours (derived from phase-constant contours) functionally dependent on excitation amplitude and the nonlinear stiffness coefficients. Within the pass band there is a frequency band termed the “caustic band” where the response is characterized by the appearance of low amplitude regions or “dead zones.” For a two-dimensional lattice having asymmetric nonlinearity, it is shown that these caustic bands are dependent on the excitation amplitude, unlike in corresponding linear models. The analytical predictions obtained are verified via comparisons to responses generated using a time-domain simulation of a finite two-dimensional nonlinear lattice. Lastly, the study demonstrates amplitude-dependent wave beaming in two-dimensional nonlinear periodic structures.

Refined Theories for the Dynamic Analysis of Sandwich Structures

2017 ◽  
Author(s):  
Serge Abrate
Keyword(s):  
Wave Propagation ◽  
Dynamic Analysis ◽  
Dynamic Loading ◽  
Sandwich Structures ◽  
Harmonic Wave ◽  
Dispersion Relations ◽  
Sandwich Beams ◽  
New Models ◽  
The Individual ◽  
Selection Of

The objective of this study is to give an overview of existing theories for analyzing the behavior of sandwich beams and plates and to develop an approach for evaluating their behavior under dynamic loading. The dispersion relations for harmonic wave propagation through sandwich structures are shown to be a sound basis for evaluating whether the individual layers are modeled properly. The results provide a guide in the selection of existing models or the development of new models.

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