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Wave flume

About: Wave flume is a research topic. Over the lifetime, 1627 publications have been published within this topic receiving 23335 citations.


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10 Oct 2008
TL;DR: In this paper, the applicability of CADMASSURF for the wave overtopping rate caused by irregular waves was examined and the calculated wave over-top rate was compared with existing formulae.
Abstract: CADMAS-SURF is a useful tool to evaluate wave actions for coastal structures. However, there are few studies concerning irregular waves by using CADMAS-SURF. The aim of this paper is to examine the applicability of CADMASSURF for the wave overtopping rate caused by irregular waves. The wave overtopping rate was calculated for uniform and sloped bottom conditions by using CADMAS-SURF. The calculated wave overtopping rate was compared with existing formulae. It is shown that CADMAS-SURF is capable of estimating the wave overtopping rate by irregular waves under broad condition with almost the same accuracy of existing formulae. It is also possible to determine the short-term overtopping rate caused by wave irregularity.

1 citations

01 Jan 2018
TL;DR: In this paper, the authors used the analytical model of Dalrymple (1984) to describe the energy dissipation through the brushwood structures and compared the results with direct force and velocity measurements, and found that the velocity inside the structure might be higher as the flow accelerates in between the gaps of the elements.
Abstract: Due to the removal of mangrove forests, coastal zones can suffer from severe erosion. One of the proposed solutions is the construction of permeable structures. This study aims to optimise the design of permeable (brushwood) structures in order to restore the sediment balance and encourage mangrove re-establishment on tropical mud coasts. Preferably wave transmission should be low in order to create a calmer climate behind the structure. In that way sediment is able to settle down, which could lead to a recovery of the mud profile. It is also preferred that reflection by the structure is low. High reflection rates cause scour holes that lead to instability of the structure. Furthermore, scour holes could hinder future mangrove re-establishment. Aiming to achieve low reflection and transmission rates, the dissipation inside the structure has to be as high as possible. Experiments were conducted in the 40 meter wave flume at the Environmental Fluid Mechanics Laboratory at TU Delft. The permeable structure was schematized as an array of cylinders. With the physical scale model various effects could be tested, including the porosity, structure width, arrangement, orientation, etc. The tests were done for 5 different wave cases, from which the wave energy distribution over reflection, dissipation and transmission was determined. The existing brushwood structures require intensive maintenance. This is partly due to the sinking of the material into the soft mud. Also, the brushwood material washes away often as it is lighter than water and difficult to constrain in vertical direction. An alternative design that requires less maintenance would be preferred. Therefore, it was interesting to see whether a comparable amount of wave dissipation could be achieved by using vertical elements only. One important finding is that in more shallow water regions, vertical and horizontal orientations have similar dissipation rates. In water regions that go more towards deep water, the horizontal structures have higher dissipation rates. This can be explained by the relative importance of the horizontal and vertical velocities due to the wave motion. In deep water vertical velocities are relatively high. As the horizontal elements have more exposure to this component in comparison to the vertical elements, they provide more dissipation. In shallow water the relative importance of the vertical velocities is lower, which explains the similar dissipation rates of the two orientations. The analytical model of Dalrymple (1984) was used to describe the energy dissipation through the structures. Drag coefficients were derived by using the calibration method. For KCl15 the drag coefficients start increasing. This is possibly due to the relative importance of the inertia force. Comparing the drag coefficients to the ones derived from direct force and velocity measurements in previous studies showed relative high values. This could be due to an underestimation of the horizontal velocity due to the wave motion. The velocity that is used is the undisturbed velocity in front of the structure. However, the velocity inside the structure might be higher as the flow accelerates in between the gaps of the elements. Furthermore, the wave cases in this research are in the Stokes 2nd and 3rd order region, indicating that the waves cannot be fully described by linear wave theory. The inertia, permeability and non-linear effects among other possible effects are not included in the analytical model of Dalrymple. Therefore, the drag coefficients do not only represent drag forces, but also other processes. To gain more insight on the physical mechanisms that affect the wave energy dissipation, it is recommended to test the same scale model with direct force and velocity measurements.

1 citations

01 Aug 1995
TL;DR: In this article, a laboratory study was carried out in which sediment concentrations and fluid velocities have been measured in case of irregular breaking waves alone and in combination with a current.
Abstract: Coastal changes occur mostly as a result of changes in sediment transport along the coast. If at cross-section A, the sediment transport is for any reason larger (or smaller) than at cross-section B, accretion (or erosion) will take place in between the two cross-sections. For prediction of coast-lines in the future, the prediction of the net sediment transport is therefore essential. Various models, such as that of Bijker, Van Rijn, Nielsen, Engelund & Hansen and Ackers & White are available to predict the sediment transport by knowledge of wave height and current strength. The reliability of these models is unknown because data under field conditions are scarce. Only few relations between sediment transport, current velocity and wave height are known. For these reasons a laboratory study was carried out to extend the knowledge of the basic phenomena in morphological processes. The study contains experiments in which sediment concentrations and fluid velocities have been measured in case of irregular breaking waves alone and in combination with a current. Chapter 2 deals with the sediment transport basics. Two types of sediment transport, the longshore and the cross-shore sediment transport are discussed and the objectives of the present experiments are presented. In Chapter 3 the experimental set up is described. The measured parameters, methods and instruments are discussed. The experimental programme of the series A and the series B I and B2 are presented. Chapter 4 covers the experimental results from test series A. The wave characteristics, fluid velocities and the influence of these parameters on the sediment concentration, sediment load and sediment transport are studied. Chapter 5 deals with the experimental results from test series B I and B2. The distribution of the sediment concentrations, fluid velocities, sediment loads and sediment transport rates over a sand bar are studied. In Chapter 6 a comparison is made between the measurements and the sediment transport models by Van Rijn and Bijker. Transport rates, concentration profiles and velocity profiles are compared. In Chapter 7 a list of conclusions and recommendations is presented.

1 citations

07 Aug 2014
TL;DR: In this paper, a mesh-free particle method has been adopted to simulate wave over-topping due to random and solitary waves and compared with past experiments and numerical studies, Satisfactory agreement has been found between present SPH model and experiment for the dynamic pressure distribution on the vertical wall while wave rushes on it.
Abstract: Smoothed Particle Hydrodynamics (SPH): a meshfree particle method has been adopted to simulate wave overtopping. Both WCSPH and ISPH models have been applied to simulate wave overtopping due to random and solitary waves and, compared with past experiments and numerical studies. These models have further been extended to study overtopping characteristics over two types of sea walls: Vertical Wall (VW) and Flaring Shaped Sea (FSS) wall. Satisfactory agreement has been found between present SPH model and experiment for the dynamic pressure distribution on the vertical wall while wave rushes on it.

1 citations


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Performance
Metrics
No. of papers in the topic in previous years
YearPapers
202331
202284
202165
202069
201964
201859