scholarly journals Investigation on the Reflection Coefficient for Seawalls Protected by a Rubble Mound Structure

2021 ◽  
Vol 9 (9) ◽  
pp. 937
Author(s):  
Luigi Pratola ◽  
Antonio Rinaldi ◽  
Matteo Gianluca Molfetta ◽  
Maria Francesca Bruno ◽  
Davide Pasquali ◽  
...  
Keyword(s):  
Reflection Coefficient ◽  
Wave Reflection ◽  
Experimental Tests ◽  
Coastal Protection ◽  
Empirical Formulas ◽  
New Approach ◽  
Wave Flume ◽  
Mound Structure ◽  
Rubble Mound ◽  
Rubble Mound Breakwaters

Sea wave reflection from coastal protection structures is one of the main issues in the coastal design process. Several empirical formulas have been proposed so far to predict reflection coefficient from rubble mound breakwaters and smooth slopes. The aim of this study is to investigate wave reflection from a rubble mound structure placed in front of a vertical concrete seawall. Several experimental tests were performed on a two-dimensional wave flume by reproducing on a rubble mound structure with a steep single primary layer armored with a novel artificial unit. A new approach for the prediction of the reflection coefficient based on dimensional analysis is also proposed, and a new empirical equation is derived. The performance of the proposed equation was compared with widespread existing formulas, and a good accuracy was found.

A new non-dimensional number for the analysis of wave reflection from rubble mound breakwaters

1996 ◽  
Vol 28 (1-4) ◽  
pp. 93-120 ◽  
Author(s):  
M.A. Davidson ◽  
P.A.D. Bird ◽  
G.N. Bullock ◽  
D.A. Huntley
Keyword(s):  
Wave Reflection ◽  
Rubble Mound ◽  
Rubble Mound Breakwaters

scholarly journals ROUGHNESS FACTOR FOR MULTI-LAYER ARMOUR AS OVERTOPPING ESTIMATOR

2020 ◽  
pp. 25
Author(s):  
Leopoldo Franco ◽  
Yuri Pepi ◽  
Stefano de Finis ◽  
Verdiana Iorio ◽  
Giorgio Bellotti ◽  
...  
Keyword(s):  
Structural Characteristics ◽  
Storm Surges ◽  
Random Wave ◽  
Roughness Factor ◽  
Coastal Structures ◽  
Wave Overtopping ◽  
Wave Flume ◽  
Physical Model Tests ◽  
Rubble Mound ◽  
Rubble Mound Breakwaters

Nowadays one of the most challenging problem for engineers is to adapt existing coastal structures to climate changes. Wave overtopping is highly sensitive to the increasing extreme water depths due to higher storm surges coupled with sea level rise. One way to face these problems for rubble mound breakwaters is to add one or more layers to the existing armour. Prediction of wave overtopping of coastal structures is presently obtained from empirical formulae in EurOtop (2018). For the case of overtopping over multi-layer armour, no validated method exists, so prediction must be based upon assumptions and judgement, with related uncertainties. This study is focused on the effects of different types of armour, the number of layer and other structural characteristics on the roughness factor f. The main effects of porosity and roughness will be investigated. This paper analyzes the results of several new physical model tests of different rubble mound breakwaters reproduced at the new medium scale random wave flume of the Department of Engineering of Roma Tre University.Recorded Presentation from the vICCE (YouTube Link): https://youtu.be/8cOdqkqQ-9s

scholarly journals WAVE OVERTOPPING ON RUBBLE MOUND BREAKWATERS

1988 ◽  
Vol 1 (21) ◽  
pp. 57 ◽  
Author(s):  
Pierliugi Aminti ◽  
Leopoldo Franco
Keyword(s):  
Hydraulic Model ◽  
Model Tests ◽  
Geometric Parameters ◽  
Random Wave ◽  
Wave Overtopping ◽  
Wave Flume ◽  
Rubble Mound ◽  
Rubble Mound Breakwaters

The paper gives the results of an extensive series of hydraulic model tests carried out in a random wave flume, in order to study the effects on wave overtopping of the main geometric parameters of a typical rubble mound breakwater with crown wall. The results have been compared with those from other studies and analyzed with different methods. Generalized design diagrams and formulae for the prediction of overtopping discharges are finally given for a large number of popular breakwater configurations.

Artificial Intelligence and Rubble-Mound Breakwater Stability

2012 ◽  
pp. 1499-1506
Author(s):  
Gregorio Iglesias Rodriguez ◽  
Alberte Castro Ponte ◽  
Rodrigo Carballo Sanchez ◽  
Miguel Ángel Losada Rodriguez
Keyword(s):  
Physical Model ◽  
Model Tests ◽  
Wave Action ◽  
Ann Model ◽  
Climate Conditions ◽  
Wave Flume ◽  
Physical Model Tests ◽  
Rubble Mound ◽  
The Stability ◽  
Rubble Mound Breakwaters

Breakwaters are coastal structures constructed to shelter a harbour basin from waves. There are two main types: rubble-mound breakwaters, consisting of various layers of stones or concrete pieces of different sizes (weights), making up a porous mound; and vertical breakwaters, impermeable and monolythic, habitually composed of concrete caissons. This article deals with rubble-mound breakwaters. A typical rubble-mound breakwater consists of an armour layer, a filter layer and a core. For the breakwater to be stable, the armour layer units (stones or concrete pieces) must not be removed by wave action. Stability is basically achieved by weight. Certain types of concrete pieces are capable of achieving a high degree of interlocking, which contributes to stability by impeding the removal of a single unit. The forces that an armour unit must withstand under wave action depend on the hydrodynamics on the breakwater slope, which are extremely complex due to wave breaking and the porous nature of the structure. A detailed description of the flow has not been achieved until now, and it is unclear whether it will be in the future in view of the turbulent phenomena involved. Therefore the instantaneous force exerted on an armour unit is not, at least for the time being, amenable to determination by means of a numerical model of the flow. For this reason, empirical formulations are used in rubble-mound design, calibrated on the basis of laboratory tests of model structures. However, these formulations cannot take into account all the aspects affecting the stability, mainly because the inherent complexity of the problem does not lend itself to a simple treatment. Consequently the empirical formulations are used as a predesign tool, and physical model tests in a wave flume of the particular design in question under the pertinent sea climate conditions are de rigueur, except for minor structures. The physical model tests naturally integrate all the complexity of the problem. Their drawback lies in that they are expensive and time consuming. In this article, Artificial Neural Networks are trained and tested with the results of stability tests carried out on a model breakwater. They are shown to reproduce very closely the behaviour of the physical model in the wave flume. Thus an ANN model, if trained and tested with sufficient data, may be used in lieu of the physical model tests. A virtual laboratory of this kind will save time and money with respect to the conventional procedure.

scholarly journals Reflection Analysis of Impermeable Slopes under Bimodal Sea Conditions

2020 ◽  
Author(s):  
Stephen Orimoloye ◽  
Harshinie Karunarathna ◽  
Dominic Reeve
Keyword(s):  
Reflection Coefficient ◽  
Wave Reflection ◽  
Experimental Tests ◽  
Random Wave ◽  
Random Waves ◽  
Coastal Structures ◽  
Test Analysis ◽  
Relative Water ◽  
Analysis Of Results ◽  
Reflection Characteristics

Understanding of reflection characteristics of coastal seawalls is crucial for design. Wave reflection can cause difficulties to small vessel manoeuvring at the harbour entrance and constitute damaging scouring at the toe of coastal structures. Previous studies have considered reflection characteristics of coastal seawalls under wind-generated random waves without paying attention to the effects of wave bimodality created by the presence of swell waves. The present study focuses on the influence of random wave bimodality on reflective characteristics of coastal seawalls. More than eight hundred experimental tests have been conducted to examine the reflection performance of impermeable sloping seawalls under bimodal waves. Reflection coefficients were computed from each test. Analysis of results suggests that both unimodal and bimodal waves give similar reflection characteristics. However, the reflection coefficient in bimodal sea states seems to be more prolonged than in the unimodal sea states. It was found that the reflection coefficient of coastal seawalls is strongly influenced by the seawall slope, the wave steepness, relative water depth, and the surf similarity parameters. A new empirical reflection equation to describe the influence of wave bimodality on the reflection characteristics of coastal seawalls has been formulated based on this study.

scholarly journals WAVE TRANSMISSION OVER LOW-CRESTED POROUS BREAKWATERS

2018 ◽  
pp. 15
Author(s):  
Theofano I. Koutrouveli ◽  
Athanassios A. Dimas
Keyword(s):  
Flow Field ◽  
Natural Environment ◽  
Wave Breaking ◽  
Wave Reflection ◽  
Coastal Protection ◽  
Breaking Wave ◽  
Geometrical Characteristics ◽  
Hydrodynamic Processes ◽  
Rubble Mound Breakwaters ◽  
The Waves

Low-crested (LC) rubble mound breakwaters are used for coastal protection. The main advantage of these structures is their mild aesthetic impact on the natural environment. As the waves approach and transmit over these structures, significant hydrodynamic processes occur in their proximal area, such as wave breaking, wave reflection, wave overtopping and transmission (Garcia et al., 2004). Many researchers have studied the hydrodynamics of flow in the vicinity of such structures, as well as the influence of their geometrical characteristics on the flow field. However, in most studies, the structures are either emerged or submerged, while the case in which the crest level of the breakwaters is at the still water level (SWL) has to be further investigated.

scholarly journals Wave and Hydrodynamic Processes in the Vicinity of a Rubble-Mound, Permeable, Zero-Freeboard Breakwater

2020 ◽  
Vol 8 (3) ◽  
pp. 206
Author(s):  
Theofano I. Koutrouveli ◽  
Athanassios A. Dimas
Keyword(s):  
Wave Reflection ◽  
Stokes Equations ◽  
Numerical Study ◽  
Flow Behavior ◽  
Wave Transmission ◽  
Leeward Side ◽  
Empirical Formulas ◽  
Wave Setup ◽  
Breaking Parameter ◽  
Rubble Mound

A numerical study for the effect of crest width, breaking parameter, and trunk permeability on hydrodynamics and flow behavior in the vicinity of rubble-mound, permeable, zero-freeboard breakwaters (ZFBs) is presented. The modified two-dimensional Navier-Stokes equations for two-phase flows in porous media with a Smagorinsky model for the subgrid scale stresses were solved numerically. An immersed-boundary/level-set method was used. The numerical model was validated for the cases of wave propagation over a submerged impermeable trapezoidal bar and a low-crested permeable breakwater. Five cases of breakwaters were examined, and the main results are: (a) The size of the crest width, B, does not notably affect the wave reflection, vorticity, and currents in the seaward region of ZFBs, while wave transmission, currents in the leeward side, and mean overtopping discharge all decrease with increasing B. A non-monotonic behavior of the wave setup is also observed. (b) As the breaking parameter decreases, wave reflection, transmission, currents, mean overtopping discharge, and wave setup decrease. This observation is also verified by relevant empirical formulas. (c) As the ZFB trunk permeability decreases, an increase of the wave reflection, currents, wave setup, and a decrease of wave transmission and mean overtopping discharge is observed.

scholarly journals WAVE RUN-UP AND REFLECTION AT RUBBLE MOUND BREAKWATERS WITH ECOPODE ARMOR LAYER

2011 ◽  
Vol 1 (32) ◽  
pp. 45 ◽  
Author(s):  
Mario Calabrese ◽  
Mariano Buccino ◽  
Francesco Ciardulli ◽  
Pasquale Di Pace ◽  
Roberto Tomasicchio ◽  
...  
Keyword(s):  
Wave Reflection ◽  
Wave Transmission ◽  
Wave Overtopping ◽  
Experimental Campaign ◽  
Coastal Defense ◽  
Rubble Mound ◽  
Run Up ◽  
Rubble Mound Breakwaters ◽  
Hydraulic Stability ◽  
Hydraulic Response

In 2008 the authors verified the hydraulic stability of a coastal defense project to be built along the NW coast of Sicily (Italy, Tomasicchio et al., 2009). The intervention consisted of shore parallel barriers armored with a relatively new eco-friendly system: ECOPODETM. In that context the idea arose of conducting an exhaustive experimental campaign on the “ hydraulic response “ of these units, including wave run-up , wave overtopping, wave transmission and wave reflection observations. The latter has been performed in 2010 at the LInC Laboratory of University of Naples “Federico II”. In this paper results on wave run-up and reflection are presented and discussed.

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