scholarly journals WAVE RUN-UP OBSERVATION AND 2DV NUMERICAL INVESTIGATION ON BEACHES PROTECTED BY STRUCTURES

2012 ◽  
Vol 1 (33) ◽  
pp. 20
Author(s):  
Renata Archetti ◽  
Maria Gabriella Gaeta
Keyword(s):  
Numerical Models ◽  
Wave Spectrum ◽  
Low Frequency ◽  
Swash Zone ◽  
Flow Motion ◽  
Transmission Area ◽  
Wave Conditions ◽  
Run Up ◽  
Incident Waves

The main parameter for the assessment of coastal vulnerability and sediment transport is the wave run-up on the beach, defining the limit of maximum flooding, but also hydrodynamic properties in the Swash Zone (SZ) are trivial for the comprehension of hydro-morphodynamic processes. Several studies have been carried out on the SZ but few literature is still available on the run-up and on SZ flows on beaches protected by Low Crested Structures (LCSs), where flow motion is driven by a combination of low frequency infra-gravity waves and incident waves. In presence of breakwaters, swash incident waves are transmitted through the structure. In the transmission area behind the structures, wave energy is shifted to higher frequencies with respect to the incident wave spectrum and in general its mean period considerably decreases with respect to the incident one. Collecting in situ run-up measurements during storms is essential to understand the SZ processes and properly calibrate their both empirical and numerical models but measuring extreme run-up is difficult, due to the severe sea conditions and due to unexpected nature of storms. The present paper present a numerical and experimental analysis of the wave run-up and of the flow properties on a beach: the study shows the different behavior of unprotected and protected beach, subjected to the same wave conditions. In particular the paper shows that submerged breakwaters reduce in general the run-up height, on the basis of the calibrated 2DV numerical simulations, under extreme wave conditions (TR >50 years), the effect of submerged breakwaters seems to be negligible on the run-up height. Moreover a preliminary empirical equation for run-up with protected beach is proposed

Model Experiments of Floating Side-by-Side Barges

2019 ◽  
Author(s):  
Kie Hian Chua ◽  
Pedro Cardozo de Mello ◽  
Kazuo Nishimoto ◽  
Yoo Sang Choo
Keyword(s):  
Numerical Models ◽  
Wave Excitation ◽  
Flow Models ◽  
Model Experiments ◽  
Dissipative Effects ◽  
Wave Elevation ◽  
Wave Heights ◽  
Wave Conditions ◽  
Incident Waves ◽  
Gap Width

Abstract The interaction between two floating vessels has been a subject of much study in recent years due to its relevance to floating liquefied natural gas (FLNG) developments. The safety and operability of these facilities are directly influenced by the wave elevation in the gap between the two vessels as well as the relative motions between the vessels. In the industry, it is common practice to use potential flow models to calculate free-surface responses under various wave conditions. Given that these numerical models are inviscid, calibration of additional damping terms are usually carried out using model tests to in order to account for the viscous dissipation on the gap hydrodynamics. However, it is known that the dissipative effects of viscosity may be nonlinear and thus, model test data obtained using one set of wave conditions may not be suitable for use in another scenario. In this paper, model experiments of two identical side-by-side barges of 280m (length) × 46m (breadth) × 16.5m (draught) under various wave excitation are described. The experiments considered a range of parameters such as gap width, wave heights, periods and wave directions. The results obtained for each set of these parameters are discussed and compared between the two types of incident waves (regular and irregular).

scholarly journals Numerical and Physical Modelling of Wave Overtopping on a Smooth Impermeable Dike with Promenade under Strong Incident Waves

2021 ◽  
Vol 9 (8) ◽  
pp. 865
Author(s):  
Maria Graça Neves ◽  
Eric Didier ◽  
Moisés Brito ◽  
María Clavero
Keyword(s):  
Wave Breaking ◽  
Numerical Models ◽  
Physical Modelling ◽  
Physical Models ◽  
Wave Overtopping ◽  
Mesh Free ◽  
Order Of Magnitude ◽  
Run Up ◽  
Turbulent Models ◽  
Incident Waves

This paper presents a study of run-up/overtopping over a smooth impermeable dike with promenade using 2D and 3D mesh-based and mesh-free numerical models and results from 2D physical modelling for strong energetic incident waves. These waves induce plunging wave breaking and a complex water/air mixture turbulent flow before overtopped the dike, a challenging configuration for numerical models. The analysis is structured in two phases: (i) evaluates the results of 2D numerical and physical models for run-up and overtopping; (ii) compares qualitatively the results of 3D numerical models for overtopping over a dike with promenade between groins located in front of a slope beach. The results indicate that the main differences obtained in run-up and overtopping are due to differences in wave generation and active absorption systems used in physical and numerical models and in turbulent models used by the numerical models. These differences lead to changes on incident wave height and on wave breaking and, consequently, on reflection, run-up and overtopping over the structure. For 3D simulation, even if larger discrepancies were found on overtopping along the dike, mean wave overtopping discharge and water flow height at the crest of the groin head show a similar order of magnitude.

scholarly journals Lidar Observations of the Swash Zone of a Low-Tide Terraced Tropical Beach under Variable Wave Conditions: The Nha Trang (Vietnam) COASTVAR Experiment

2020 ◽  
Vol 8 (5) ◽  
pp. 302 ◽  
Author(s):  
Luís Pedro Almeida ◽  
Rafael Almar ◽  
Chris Blenkinsopp ◽  
Nadia Senechal ◽  
Erwin Bergsma ◽  
...  
Keyword(s):  
Field Experiment ◽  
Wave Height ◽  
Sandy Beach ◽  
Wind Waves ◽  
Swash Zone ◽  
Key Factor ◽  
Wave Conditions ◽  
Run Up ◽  
Topographic Surveys ◽  
Lidar Observations

A field experiment was conducted at a tropical microtidal intermediate sandy beach with a low tide terrace (Nha Trang, Vietnam) to investigate the short-term swash-zone hydrodynamics and morphodynamics under variable wave conditions. Continuous 2D Lidar scanner observations of wave height at the lower foreshore, subsequent run-up and swash-induced topographic changes were obtained. These data were complemented by detailed real-time kinematic GPS topographic surveys. Variable wave and tide conditions were experienced during the field experiment with relatively large swell waves (offshore significant wave height, Hs = 0.9 m to 1.3 m; peak wave period, Tp = 8 to 12 s) concomitant with spring tides at the beginning of the period, followed by mild wind waves (offshore Hs under 0.5 m and Tp 5 s) and neap tides. This resulted in the following morphological sequence: berm erosion followed by rapid neap berm reformation and beach recovery within a few days. New insights into the link between intra-tidal swash dynamics and daily beach profile evolution were found using the Lidar dataset. While waves directly cause morphology changes on a wave-by-wave basis, tidal levels were found to be a key factor in determining the morphological wave-effect (accretive or erosive) due to modulated interaction between surf and swash hydro-morphodynamics.

Extreme Forces in Short-Crested Seas

1980 ◽  
Vol 20 (06) ◽  
pp. 567-578
Author(s):  
S.W. Huntington ◽  
G. Gilbert
Keyword(s):  
Transfer Functions ◽  
Extreme Values ◽  
Numerical Models ◽  
Wave Spectrum ◽  
Standard Theory ◽  
Total Force ◽  
Random Waves ◽  
Linear Superposition ◽  
Incident Waves ◽  
The Waves

Abstract The overall wave force on a large structure in a real multidirectional sea does not occur in a single direction but is a vector randomly varying in magnitude and direction. Although existing theories enable us to calculate the extremes of the orthogonal components of force, the designer needs the extreme resultant or total force. A theory is presented for estimating the extremes of the resultant and is confirmed by experimental measurement. Introduction Recent development of offshore resources in deep water and severe environmental conditions has led to the use of monolithic concrete structures. These structures have members large enough to modify the wave field, and are regarded as being in the diffraction regime of wave loading. Thus, the induced forces and moments are considered linear responses to the incident waves. Estimation of the forces and moments on such structures is based on the linear diffraction theory of Havelock. Several numerical models are used to compute the transfer functions between the incident waves and resuring forces and moments on large structures of arbitrary shape. In general, such models give the magnitude and phase of the transfer function between the waves and the loading at a range of discrete frequencies and angles of wave incidence. In parallel with the numerical approach, analytical methods have been developed to give directly the transfer functions for force and moment on a vertical cylinder in long-crested random waves. This analytical approach has also been extended to real seas that are multidirectional (short crested). In such seas, forces and moments are induced on structures both in line with and at right angles to the principal wave direction. The method gives the transfer functions between the components of force and moment and the total wave spectrum for any particular angular distribution of wave energy. The validity of this direct approach in short-crested seas has been confirmed by laboratory model tests in multidirectional random waves. These two approaches are complementary in that the numerical method allows estimation for regular waves on arbitrarily-shaped real structures; the analytical and laboratory studies allows the extension of results to real multidirectional random seas using the principle of superposition. By using this method, it is possible to compute the spectra of force and moment in two horizontal component directions on a real structure in a real short-crested sea. Since linear superposition is used both in the frequency and angular domains, the calculated component forces and moments also are linear with respect to the waves. However, the spectra of force and moment on a structure are of little direct value to designers concerned with primary failure. They are interested in the possible extremes and will want to set design limits on the forces and moments that are unlikely to be exceeded during the lift of the structure. Since the component forces and moments are linear responses to the waves, the statistical technique used to describe extreme wave elevations can be used to describe the extremes of the components of the loading. This method requires only the gross parameters of the spectra. Since the total (vector) force or moment combines the components and their probabilities in a nonlinear manner, the vital extreme values cannot be derived from the standard theory. This paper presents an analytical solution to this vector problem. SPEJ P. 567＾

scholarly journals WAVE RUN-UP ON A NATURAL BEACH

1988 ◽  
Vol 1 (21) ◽  
pp. 10
Author(s):  
Mitsuo Takezawa ◽  
Masaru Mizuguchi ◽  
Shintaro Hotta ◽  
Susumu Kubota
Keyword(s):  
Surf Zone ◽  
Wave Theory ◽  
Transformation Model ◽  
Wave Transformation ◽  
Electromagnetic Current ◽  
Swash Zone ◽  
Reflected Waves ◽  
Wave Heights ◽  
Run Up ◽  
Incident Waves

The swash oscillation, waves and water particle velocity in the surf zone were measured by using 16 mm memo-motion cameras and electromagnetic current meters. It was inferred that incident waves form two-dimensional standing waves with the anti-node in the swash slope. Separation of the incident waves and reflected waves was attempted with good results using small amplitude long wave theory. Reflection coefficient of individual waves ranged between 0.3 and 1.0. The joint distribution of wave heights and periods in the swash oscillation exhibited different distribution from that in and outside the surf zone. This indicates that simple application of wave to wave transformation model fails in the swash zone.

scholarly journals VORTICAL VLF MOTIONS UNDER SHORE-NORMAL INCIDENT WAVES

2012 ◽  
Vol 1 (33) ◽  
pp. 58 ◽  
Author(s):  
Matthieu Andreas De Schipper ◽  
Ad Reniers ◽  
Jamie MacMahan ◽  
Roshanka Ranasinghe
Keyword(s):  
Numerical Model ◽  
Incident Wave ◽  
Large Scale ◽  
Wave Spectrum ◽  
Normal Wave ◽  
Low Frequency ◽  
Velocity Fluctuations ◽  
Model Simulations ◽  
Frequency Spread ◽  
Incident Waves

Field observations and numerical model simulations are examined to investigate the magnitude of vortical very low frequency (VLF) velocity fluctuations (i.e. large scale surfzone eddies) under different offshore wave forcing. Observations of vortical VLF motions under shore -normal wave incidence at Duck, NC, USA are re-analyzed and compared with the characteristics of the incident wave spectrum. Long wave periods and narrow frequency spread incident waves were found to coincide with stronger vortical VLF motions. Numerical model simulations investigating the effect of the incident wave parameters in a more isolated way confirm the observed effect of frequency spread and wave period on the magnitude of VLF motions. Variations in incident wave spectrum resulted in changes in the vortical VLF magnitude of the same order as the magnitude of the vortical VLF velocity fluctuations themselves. These results imply that under shore-normal incident waves strong vortical VLF velocity fluctuations in the surfzone are more likely under swell conditions and at swell dominated coasts.

scholarly journals Artificial Intelligence Application on Sediment Transport

2021 ◽  
Vol 9 (6) ◽  
pp. 600
Author(s):  
Hyun Dong Kim ◽  
Shin-ichi Aoki
Keyword(s):  
Sediment Transport ◽  
Numerical Models ◽  
Beach Nourishment ◽  
Hydraulic Model ◽  
Alternative Methods ◽  
Cross Sectional ◽  
Sand And Gravel ◽  
Incident Waves ◽  
Artificial Intelligence Application ◽  
Deep Learning Model

When erosion occurs, sand beaches cannot maintain sufficient sand width, foreshore slopes become steeper due to frequent erosion effects, and beaches are trapped in a vicious cycle of vulnerability due to incident waves. Accordingly, beach nourishment can be used as a countermeasure to simultaneously minimize environmental impacts. However, beach nourishment is not a permanent solution and requires periodic renourishment after several years. To address this problem, minimizing the period of renourishment is an economical alternative. In the present study, using the Tuvaluan coast with its cross-sectional gravel nourishment site, four different test cases were selected for the hydraulic model experiment aimed at discovering an effective nourishment strategy to determine effective alternative methods. Numerical simulations were performed to reproduce gravel nourishment; however, none of these models simultaneously simulated the sediment transport of gravel and sand. Thus, an artificial neural network, a deep learning model, was developed using hydraulic model experiments as training datasets to analyze the possibility of simultaneously accomplishing the sediment transport of sand and gravel and supplement the shortcomings of the numerical models.

scholarly journals HF Radars for Wave Energy Resource Assessment Offshore NW Spain

2021 ◽  
Vol 13 (11) ◽  
pp. 2070
Author(s):  
Ana Basañez ◽  
Vicente Pérez-Muñuzuri
Keyword(s):  
Wave Energy ◽  
Numerical Models ◽  
Wave Spectrum ◽  
Energy Resource ◽  
Electrical Energy ◽  
Resource Assessment ◽  
Electricity Production ◽  
Statistical Validation ◽  
Wave Energy Converters ◽  
Energy Converters

Wave energy resource assessment is crucial for the development of the marine renewable industry. High-frequency radars (HF radars) have been demonstrated to be a useful wave measuring tool. Therefore, in this work, we evaluated the accuracy of two CODAR Seasonde HF radars for describing the wave energy resource of two offshore areas in the west Galician coast, Spain (Vilán and Silleiro capes). The resulting wave characterization was used to estimate the electricity production of two wave energy converters. Results were validated against wave data from two buoys and two numerical models (SIMAR, (Marine Simulation) and WaveWatch III). The statistical validation revealed that the radar of Silleiro cape significantly overestimates the wave power, mainly due to a large overestimation of the wave energy period. The effect of the radars’ data loss during low wave energy periods on the mean wave energy is partially compensated with the overestimation of wave height and energy period. The theoretical electrical energy production of the wave energy converters was also affected by these differences. Energy period estimation was found to be highly conditioned to the unimodal interpretation of the wave spectrum, and it is expected that new releases of the radar software will be able to characterize different sea states independently.

scholarly journals Sub-Level Stoping in an Underground Limestone Quarry: An Analysis of the State of Stress in an Evolutionary Scenario

2016 ◽  
Vol 61 (1) ◽  
pp. 199-216 ◽  
Author(s):  
Marilena Cardu ◽  
Sergio Dipietromaria ◽  
Pierpaolo Oreste
Keyword(s):  
Numerical Models ◽  
The State ◽  
In Situ Tests ◽  
Future Scenario ◽  
Limestone Quarry ◽  
Geomechanical Properties ◽  
State Of Stress ◽  
Upper Level ◽  
Pillar Structure

Abstract The aim of this study was to evaluate the state of stress of a „voids-pillar“ structure excavated by means of the sub-level stoping method in an underground limestone quarry near Bergamo (Italy). Both the current structure of the quarry (i.e. the rooms exploited till now) and a possible future scenario were analysed using the (FDM) FLAC 2D code. The quarry has been in operation since 1927; at present, exploitation is carried out underground via the sub-level stoping method. Exploitation involves two levels, with 5 rooms on the upper level and 9 rooms on the lower level. After analysing data obtained from laboratory and in situ tests carried out on rock samples and natural discontinuities, the geomechanical properties of the medium, knowledge of which is essential in order to establish the parameters that must be included in the numerical model, were evaluated. The implementation of three numerical models made it possible to study both the present conditions of quarry exploitation and the evolution of the exploited rooms, as well as a possible expansion involving a third level of rooms. Using the results obtained regarding the stress-strain present in the pillars, a potential change in room geometry was proposed aimed at reducing the stress state inside the pillars, decreasing plasticity and increasing overall quarry safety.

Analysis of TBM Tunnel Behavior in Jointed Rock Mass

2011 ◽  
Vol 90-93 ◽  
pp. 2033-2036 ◽  
Author(s):  
Jin Shan Sun ◽  
Hong Jun Guo ◽  
Wen Bo Lu ◽  
Qing Hui Jiang
Keyword(s):  
Rock Mass ◽  
Numerical Models ◽  
Jointed Rock ◽  
In Situ Stress ◽  
Jointed Rock Mass ◽  
Joint Orientation ◽  
Joint Spacing ◽  
Factors Affecting ◽  
Dip Angle

The factors affecting the TBM tunnel behavior in jointed rock mass is investigated. In the numerical models the concrete segment lining of TBM tunnel is concerned, which is simulated as a tube neglecting the segment joint. And the TBM tunnel construction process is simulate considering the excavation and installing of the segment linings. Some cases are analyzed with different joint orientation, joint spacing, joint strength and tunnel depth. The results show that the shape and areas of loosing zones of the tunnel are influenced by the parameters of joint sets and in-situ stress significantly, such as dip angle, spacing, strength, and the in-situ stress statement. And the stress and deformation of the tunnel lining are influenced by the parameters of joint sets and in-situ stress, too.

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