Experimental Studies of Surface Wave Reflection by Longshore Bars and a Sloping Seawall

2002 ◽  
Author(s):  
P. Dong ◽  
Y. Wang
Keyword(s):  
Laboratory Experiments ◽  
Wave Reflection ◽  
Experimental Studies ◽  
Considerable Influence ◽  
Wave Surface ◽  
Regular Waves ◽  
Wave Flume ◽  
The Waves ◽  
Resonant Reflection ◽  
Reflection Characteristics

Laboratory experiments have been performed to investigate the effects of a seawall on resonant reflection by a fixed periodic bar system on the seabed. The experiments were conducted in a wave flume. A series of five fixed bars was placed in front of a seawall with 1:1 slope. Regular waves with wave height 0.04m and wave periods from 0.8 to 1.20 seconds were used. The tests were performed for the cases with and without the seawall. The wave surface elevations were measured at seven locations in front of the seaward and in either side the bar patch. Based on the preliminary analysis of measured wave time series, it was found that the presence of the seawall has considerable influence on the reflection characteristics of the waves in front of the bar field.

scholarly journals THE DYNAMIC RESPONSE OF SHINGLE BEACHES TO RANDOM WAVES

1988 ◽  
Vol 1 (21) ◽  
pp. 130 ◽  
Author(s):  
K.A. Powell
Keyword(s):  
Field Data ◽  
Wave Reflection ◽  
Relative Magnitude ◽  
Random Wave ◽  
Random Waves ◽  
Wave Flume ◽  
Probabilistic Distribution ◽  
Laboratory Results ◽  
Run Up ◽  
Reflection Characteristics

An extensive laboratory investigation into the behaviour of shingle beaches has been undertaken using a large random wave flume. The study utilised a lightweight material scaled to reproduce the correct permeability of the beach, and the correct threshold and relative magnitude of the onshore/offshore movement. Results are presented describing both the wave reflection characteristics of the beach and the probabilistic distribution of wave run-up crests on the foreshore. Where possible the laboratory results are validated against field data.

scholarly journals EXPERIMENTAL ANALYSIS OF EROSIVE COHESIVE COASTLINE MORPHOLOGY

2011 ◽  
Vol 1 (32) ◽  
pp. 53
Author(s):  
Bastien Caplain ◽  
Dominique Astruc ◽  
Vincent Regard ◽  
Frédéric Moulin
Keyword(s):  
Laboratory Experiments ◽  
Regular Waves ◽  
Similarity Parameter ◽  
Wave Flume ◽  
Cliff Erosion ◽  
Recession Rate ◽  
Self Organized ◽  
Coastal Cliff ◽  
Wave Energy Flux

Laboratory experiments have been performed in a wave flume to investigate the coastal cliff recession under regular waves forcing. The different processes of the cliff erosion cycle are described and we focus on bottom evolution, which seem mostly depend on the surf similarity parameter ξ. We observed steep planar (ξ > 0.7), gentle planar (0.5 < ξ < 0.7) and bared (ξ < 0.5) profiles. We noticed different sandbar dynamics including either steady or unsteady self-sustained oscillating states. Then we estimate the role of the self-organized material on the cliff recession rate. We show that the cliff erosion increases with the wave energy flux and is stronger for a gentle planar profile than for a bared profile of bottom morphology. However, the cliff recession rate as a function of the cliff height is not monotonic due to a different dynamics of bottom morphologies.

Deterministic Reproduction of Nonlinear Waves

2002 ◽  
Author(s):  
Jesper Skourup ◽  
Martin J. Sterndorff
Keyword(s):  
Time Series ◽  
Nonlinear Waves ◽  
Second Order ◽  
Irregular Waves ◽  
Regular Waves ◽  
Order Model ◽  
Wave Flume ◽  
Non Linear ◽  
The Waves ◽  
Second Order Model

A method for deterministic reproduction of non-linear long-crested waves has been implemented. The model is used for non-linear reproduction of measured wave time series from a model test programme in a wave flume. Regular waves, irregular waves and focused waves have been reproduced with the model. Based on measured surface elevation time series at one location in the flume the elevation time series and the kinematics have been reproduced at another location using both linear theory and the second order model. The numerical results have been compared with measurements and it is found that the second order model is able to reproduce the correct shape of the waves as they propagate in the flume — even when the waves are highly non-linear.

Kajian Model Fisik Pengaruh Freeboard dan Susunan Buis Beton Sebagai Pemecah Gelombang Tenggelam Ambang Rendah (Pegar) Dalam Mereduksi Gelombang

2017 ◽  
Vol 1 (2) ◽  
pp. 34
Author(s):  
Zulkarnain Zulkarnain ◽  
Nadjadji Anwar
Keyword(s):  
Low Cost ◽  
Relative Depth ◽  
Submerged Breakwater ◽  
Wave Flume ◽  
Concrete Cylinder ◽  
Engineering Department ◽  
Sea Area ◽  
The Waves ◽  
Transmission Test ◽  
Better Than

The Research Center and Development of Water (Puslitbang) is currently developing the Submerged Breakwater in shallow sea area (PEGAR). The author is interested to examine the material that easily obtained in the field of RCP concrete cylinder. The observation is how it to be ability in function as submerged breakwater an go green and low cost. The physical model of wave transmission test is how the response to the structure in ability to damping of wave as the breakwater function. In this research breakwater used is submerged breakwater type by using concrete cylinder (buis beton). The purpose from this research is to know how the response of breakwater structure to the waves through it, with some variation of the structure by creating a structure with three variations of the arrangement and freeboard that is the relative depth with the crest width is constant. The wave generated test in this study is using regular waves in wave flume at FTSP Civil Engineering Department of Institute Technology Ten November. From the analysis of the effect of the installation of submerged breakwater by using concrete cylinder to the wave damping value, it can be concluded that the factors that are very influential is the freeboard and the composition of concrete cylinder. Scenario A (rigid vertical massive) is capable of producing the smallest value of kt is 0.33. As for scenario B (rigid horyzontal massive) with a damping value of 0.5, while the scenario C (rigid permeable) is only able to produce kt value of 0.71. Scenario A is better than scenario B and C Because the position of arrangement of A is very good used to damp wave in small or big freeboard conditions.

Applications of Bentonite to Soil Decontamination

2018 ◽  
Vol 69 (7) ◽  
pp. 1695-1698
Author(s):  
Marin Rusanescu ◽  
Carmen Otilia Rusanescu ◽  
Gheorghe Voicu ◽  
Mihaela Begea
Keyword(s):  
Heavy Metals ◽  
Heavy Metal ◽  
Laboratory Experiments ◽  
Experimental Studies ◽  
Heavy Metal Concentration ◽  
Polluted Soil ◽  
Raw Material ◽  
Soil Decontamination ◽  
Metal Retention ◽  
Removal Of Heavy Metals

A calcium bentonite from Orasu Nou deposit (Satu Mare Romania) was used as raw material. We have conducted laboratory experiments to determine the influence of bentonite on the degree of heavy metal retention. It has been observed that the rate of retention increases as the heavy metal concentration decreases. Experimental studies have been carried out on metal retention ( Zn) in bentonite. In this paper, we realized laboratory experiments for determining the influence of metal (Zn) on the growth and development of two types of plants (Pelargonium domesticum and Kalanchoe) and the effect of bentonite on the absorption of pollutants. These flowers were planted in unpolluted soil, in heavy metal polluted soil and in heavy metal polluted soil to which bentonite was added to observe the positive effect of bentonite. It has been noticed that the flowers planted in unpolluted soil and polluted with heavy metals to which bentonite has been added, the flowers have flourished, the leaves are still green and the plants whose soils have been polluted with heavy metals began to dry after 6 days, three weeks have yellowish leaves and flowers have dried. Experiments have demonstrated the essential role of bentonite for the removal of heavy metals polluted soil.

scholarly journals Wave Breaking in Undular Bores with Shear Flows

Water Waves ◽  
2021 ◽  
Author(s):  
Maria Bjørnestad ◽  
Henrik Kalisch ◽  
Malek Abid ◽  
Christian Kharif ◽  
Mats Brun
Keyword(s):  
Turbulent Flows ◽  
Wave Breaking ◽  
Vries Equation ◽  
Kdv Equation ◽  
Flow Depth ◽  
Present Contribution ◽  
Undular Bore ◽  
Wave Flume ◽  
The Kdv Equation ◽  
The Waves

AbstractIt is well known that weak hydraulic jumps and bores develop a growing number of surface oscillations behind the bore front. Defining the bore strength as the ratio of the head of the undular bore to the undisturbed depth, it was found in the classic work of Favre (Ondes de Translation. Dunod, Paris, 1935) that the regime of laminar flow is demarcated from the regime of partially turbulent flows by a sharply defined value 0.281. This critical bore strength is characterized by the eventual breaking of the leading wave of the bore front. Compared to the flow depth in the wave flume, the waves developing behind the bore front are long and of small amplitude, and it can be shown that the situation can be described approximately using the well known Kortweg–de Vries equation. In the present contribution, it is shown that if a shear flow is incorporated into the KdV equation, and a kinematic breaking criterion is used to test whether the waves are spilling, then the critical bore strength can be found theoretically within an error of less than ten percent.

scholarly journals Large-Scale Laboratory Experiments on Mussel Dropper Lines in Ocean Surface Waves

2020 ◽  
Vol 9 (1) ◽  
pp. 29
Author(s):  
Rebekka Gieschen ◽  
Christian Schwartpaul ◽  
Jannis Landmann ◽  
Lukas Fröhling ◽  
Arndt Hildebrandt ◽  
...  
Keyword(s):  
Large Scale ◽  
Laboratory Experiments ◽  
Blue Mussel ◽  
Farming Systems ◽  
Quality Parameter ◽  
Large Wave ◽  
Marine Aquaculture ◽  
Ocean Surface Waves ◽  
Wave Flume ◽  
Waves And Currents

The rapid growth of marine aquaculture around the world accentuates issues of sustainability and environmental impacts of large-scale farming systems. One potential mitigation strategy is to relocate to more energetic offshore locations. However, research regarding the forces which waves and currents impose on aquaculture structures in such conditions is still scarce. The present study aimed at extending the knowledge related to live blue mussels (Mytilus edulis), cultivated on dropper lines, by unique, large-scale laboratory experiments in the Large Wave Flume of the Coastal Research Center in Hannover, Germany. Nine-months-old live dropper lines and a surrogate of 2.0 m length each are exposed to regular waves with wave heights between 0.2 and 1.0 m and periods between 1.5 and 8.0 s. Force time histories are recorded to investigate the inertia and drag characteristics of live mussel and surrogate dropper lines. The surrogate dropper line was developed from 3D scans of blue mussel dropper lines, using the surface descriptor Abbott–Firestone Curve as quality parameter. Pull-off tests of individual mussels are conducted that reveal maximum attachment strength ranges of 0.48 to 10.55 N for mussels that had medium 3.04 cm length, 1.60 cm height and 1.25 cm width. Mean drag coefficients of CD = 3.9 were found for live blue mussel lines and CD = 3.4 for the surrogate model, for conditions of Keulegan–Carpenter number (KC) 10 to 380, using regular wave tests.

Experimental Study of Wave Force Distribution on a Monopile Structure

2018 ◽  
Author(s):  
Malene H. Vested ◽  
Stefan Carstensen ◽  
Erik Damgaard Christensen
Keyword(s):  
Experimental Studies ◽  
Cost Effective ◽  
Wave Force ◽  
Offshore Wind ◽  
Irregular Waves ◽  
Force Distribution ◽  
Wave Forces ◽  
Total Force ◽  
Wave Flume ◽  
Effective Manner

As the demand for offshore wind energy continues to grow, the strive to understand the wave forces acting on the substructure of the wind turbines continues. In regard to wind turbine design, it is vital to consider not only the total wave force, but also the local wave forces. Local forces are particularly important for the design of secondary structures as e.g. mooring platforms. Typically, however, experimental studies mainly concern total forces or idealized local forces. We present here a rather simple way to measure local forces along a model monopile. The study is conducted in a wave flume of 28 m in length, in which waves are generated by a piston-type wave maker at a water depth of 0.515 m and shoal onto a bed of slope 1:25. A model monopile is installed and subjected to forcing from a series of both regular and irregular waves. In the experimental set-up, the model monopile is fixed at the bottom and the top and consists of seven independent cylindrical sections. The cylindrical sections are connected by force transducers which measure local shear, and so the associated local forces may be determined. The measured local forces are compared to the force distribution given by Morisons equation combined with linear theory and Wheeler stretching, which is a force estimate commonly used in the industry. This study shows that the total force is rather well captured by Morison’s equation. The force distribution estimated from Morison’s equation, however, shows larger discrepancies from the measured forces. This encourages for further measurements. In this study, we show that it is possible to measure force distribution on a model monopile in a simple and cost-effective manner. The aim is here to demonstrate the method and we will later present a larger body of work associated with the outcome of the measurements.

A Lagrangian Model for Irregular Waves and Wave Kinematics

2003 ◽  
Vol 125 (2) ◽  
pp. 94-102 ◽  
Author(s):  
Svein Helge Gjøsund
Keyword(s):  
Iterative Method ◽  
Irregular Waves ◽  
Lagrangian Model ◽  
Surface Zone ◽  
Wave Interactions ◽  
Wave Flume ◽  
Wave Kinematics ◽  
Eulerian Formulation ◽  
The Waves ◽  
Good Agreement

It has proven difficult to describe the kinematics in irregular waves satisfactorily, in particular for the surface zone in broad-banded waves. A Lagrangian approach offers distinct advantages in this respect, eliminating the need for extrapolation of solutions or “stretching” of coordinates. This paper presents a model of irregular waves based on superposition of linear Lagrangian wave components, using an iterative method to obtain the Eulerian solution. This approach yields theoretically consistent results everywhere in the waves, and comparisons with wave flume measurements show good agreement. Also, the linear Lagrangian model includes wave interactions that would be nonlinear in an Eulerian formulation.

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