Showing papers on "Wave flume published in 2016"
TL;DR: In this article, the impact of tsunami bores on a square prism model having different orientations to the flow direction was investigated in a 14m long, 1.2m wide and 0.8m deep wave flume equipped with an automatic gate designed to generate a tsunami bore.
90 citations
TL;DR: In this article, the effect of vegetation on sea-swell and infragravity-band (IG) waves and wave setup is investigated in two modes: phase-averaged (surfbeat) and phase-resolving (non-hydrostatic) modes.
Abstract: Aquatic vegetation in the coastal zone attenuates wave energy and reduces the risk of coastal hazards, e.g., flooding. Besides the attenuation of sea-swell waves, vegetation may also affect infragravity-band (IG) waves and wave setup. To date, knowledge on the effect of vegetation on IG waves and wave setup is lacking, while they are potentially important parameters for coastal risk assessment. In this study, the storm impact model XBeach is extended with formulations for attenuation of sea-swell and IG waves, and wave setup effects in two modes: the sea-swell wave phase-resolving (nonhydrostatic) and the phase-averaged (surfbeat) mode. In surfbeat mode, a wave shape model is implemented to capture the effect of nonlinear wave-vegetation interaction processes on wave setup. Both modeling modes are verified using data from two flume experiments with mimic vegetation and show good skill in computing the sea-swell and IG wave transformation, and wave setup. In surfbeat mode, the wave setup prediction greatly improves when using the wave shape model, while in nonhydrostatic mode (nonlinear) intrawave effects are directly accounted for. Subsequently, the model is used for a range of coastal geomorphological configurations by varying bed slope and vegetation extent. The results indicate that the effect of wave-vegetation interaction on wave setup may be relevant for a range of typical coastal geomorphological configurations (e.g., relatively steep to gentle slope coasts fronted by vegetation).
69 citations
TL;DR: In this article, the role of individual vegetation parameters in this water-vegetation interaction was evaluated by conducting drag force measurements under a wide range of wave loadings in a large wave flume, where artificial vegetation elements were used to manipulate stiffness, frontal area in still water and material volume as a proxy for biomass.
53 citations
TL;DR: In this article, the results of a study carried out in the Large Wave Flume (Groser Wellenkanal, GWK), where waves of periods between 30 s and more than 100 s at 1 m water depth were successfully generated with a piston type wave maker.
50 citations
TL;DR: The Overtopping BReakwaterfor Energy Conversion (OBREC) as discussed by the authors is an overtopping wave energy converter, totally embedded in traditional rubble mound breakwaters, which consists of a reinforced concrete front reservoir designed with the aim of capturing the wave over-topping in order to produce electricity.
Abstract: The Overtopping BReakwaterfor Energy Conversion (OBREC) is an overtopping wave energy converter, totally embedded in traditional rubble mound breakwaters. The device consists of a reinforced concrete front reservoir designed with the aim of capturing the wave overtopping in order to produce electricity. The energy is extracted through low head turbines, using the difference between the water levels in the reservoir and the sea water level. This paper analyzes the OBREC hydraulic performances based on physical 2D model tests carried out at Aalborg University (DK). The analysis of the results has led to an improvement in the overall knowledge of the device behavior, completing the main observations from the complementary tests campaign carried out in 2012 in the same wave flume. New prediction formula are presented for wave reflection, the overtopping rate inside the front reservoir and at the rear side of the structure. Such methods have been used to design the first OBREC prototype breakwater in operation since January 2016 at Naples Harbor (Italy).
45 citations
TL;DR: In this paper, an experimental investigation of the dynamic responses of a freestanding bridge tower model under coupled wave and wind actions was performed in a wind tunnel and wave flume and the test results indicated that the coupled wind-wave effects are clear for lower wind speed with regular waves when the wave period is in the resonant region of the structures.
42 citations
TL;DR: In this paper, a wave load simulation of fixed offshore substructures in waves with the presence of uniform current was carried out by numerical wave tank technique using the commercial software, FLUENT.
41 citations
TL;DR: In this paper, a causal FIR filter was used to compensate a large control delay in some existing setups, and the results showed that the superharmonics of such waves can also be well absorbed by the system.
41 citations
TL;DR: In this article, the authors compare the morphologic response to overwash on a gravel barrier (BARDEX 2008 experiment) with that on a sandy barrier (bARDEX II), and understand the influence of wave period on overwash characteristics and sediment transport.
36 citations
TL;DR: Schimmels et al. as mentioned in this paper studied the propagation and run-up of long tsunami-like waves in the 300m long Large Wave Flume (GWK), Hannover, Germany and analyzed the feasibility of experiments on tsunami runup in large facilities.
31 citations
TL;DR: In this article, the effect of water depth on gap resonance of two side-by-side rectangular boxes is examined in a 2D numerical wave flume at various gap widths and body drafts.
TL;DR: In this paper, wave run-up on a slender pile due to non-breaking regular waves is investigated by means of small-scale experiments performed in the 2m wide wave flume of Leichtweiss-Institute for Hydraulic Engineering and Water Resources (LWI) in Braunschweig, Germany.
TL;DR: In this paper, a meshless numerical wave flume is formed by combining the generalized finite difference method (GFDM), the Runge-Kutta method, the semi-Lagrangian technique, the ramping function and the sponge layer to efficiently analyze the propagation of nonlinear water waves.
TL;DR: In this article, six solitary wave generations by different mathematical approximations are investigated using a piston type wave maker at dimensionless amplitudes ranging from 0.1 to 0.6 and two water depths.
TL;DR: In this article, a novel approach for simulating Oscillating Water Column (OWC) using lattice Boltzmann method (LBM) is presented. And the experimental and numerical setup are described.
TL;DR: In this article, a computer-controlled lift gate instantaneously released 6.5m 3 of water into a 32m flume with shallow ponded water, creating a hydraulic bore that transported sand from an upstream source dune.
TL;DR: In this article, a coarse sand beach constructed in a large-scale laboratory wave flume was used to study the impact of swash zone sheet flow and suspended sediment transport rates.
TL;DR: In this paper, a two-dimensional numerical wave flume is established based on finite element and volume of fluid (VOF) methods for incompressible viscous flow, and the numerical model is used to simulate waves interacting with single and double horizontal floating cylinders perpendicular to the direction of wave propagation.
TL;DR: In this article, the authors studied the internal characteristics and formation process of the strata in collapse depressions with consideration of re-stratification caused by sediment liquefaction in coastal areas.
TL;DR: In this article, an experimental study investigates the generation and propagation of regular water waves and their interactions with an in-house fabricated horizontal-axis 3-bladed Savonius rotor in an experimental wave flume (EWF) equipped with a piston-type wave maker with active absorption capability.
TL;DR: In this paper, a series of experiments in a 104m-long large wave flume (LWF) using an acoustic Doppler velocimeter (ADV) and two oxygen microelectrodes (tips ~2 mm apart) mounted on a sturdy tripod were conducted.
Abstract: Interest in validating the eddy covariance (EC) technique under wave-induced flows led to a series of experiments in a 104-m-long large wave flume (LWF) using an acoustic Doppler velocimeter (ADV) and two oxygen microelectrodes (tips ~2 mm apart) mounted on a sturdy tripod. Four additional ADVs positioned within the flume provided comparative near-bed velocity measurements during experiments with irregular waves over a sand bed. These measurements revealed that modifications of local turbulence by the tripod frame were insignificant. However, errors in velocity measurements were at times observed for setups where the microelectrode tips protruded into the ADV’s measurement volume. Disparate oxygen microelectrode velocity effects (stirring sensitivities) combined with response time offsets were also identified as problems, adding biases to EC flux derivations. Microelectrode velocity effects were further investigated through modeling designed to mimic the LWF data, and through examination of a 12-h...
TL;DR: In this article, a depth-averaged 2D model is developed to simulate unsteady flow and non-uniform sediment transport in coastal waters, where the current motion is computed by solving the phase-averaging 2-D shallow water flow equations reformulated in terms of total-flux velocity, accounting for the effects of wave radiation stresses and general diffusion or mixing induced by current, waves, and wave breaking.
Abstract: A depth-averaged 2-D model has been developed to simulate unsteady flow and nonuniform sediment transport in coastal waters. The current motion is computed by solving the phase-averaged 2-D shallow water flow equations reformulated in terms of total-flux velocity, accounting for the effects of wave radiation stresses and general diffusion or mixing induced by current, waves, and wave breaking. The cross-shore boundary conditions are specified by assuming fully developed longshore current and wave setup that are determined using the reduced 1-D momentum equations. A 2-D wave spectral transformation model is used to calculate the wave height, period, direction, and radiation stresses, and a surface wave roller model is adopted to consider the effects of surface roller on the nearshore currents. The nonequilibrium transport of nonuniform total-load sediment is simulated, considering sediment entrainment by current and waves, the lag of sediment transport relative to the flow, and the hiding and exposure effect of nonuniform bed material. The flow and sediment transport equations are solved using an implicit finite volume method on a variety of meshes including nonuniform rectangular, telescoping (quadtree) rectangular, and hybrid triangular/quadrilateral meshes. The flow and wave models are integrated through a carefully designed steering process. The model has been tested in three field cases, showing generally good performance.
TL;DR: In this article, a combination of physical and detailed numerical modeling is used to predict cross-shore sediment sorting processes using data from large-scale wave flume experiments, and the results are in agreement with experimental data, showing its capabilities in functioning as a tool to predict sorting processes.
TL;DR: In this article, a numerical experiment was carried out to simulate the flow, wave and sediment transport in the Gold Coast Seaway area, Gold Coast, Australia, in order to test its ability to reproduce wave and tide induced currents and the longshore sediment transport.
TL;DR: In this article, the authors assess to which extent common quantitative formulae for predicting local scour and drag forces on rigid cylindrical obstacles are valid for the estimation of scour, and hence applicable to predict plant establishment and survival under contrasting wave conditions.
TL;DR: In this article, the role of nonlinear wave evolution in the formation of extreme run-up events on a vertical wall is investigated, and it is shown that extreme runup events in deep water may occur as a result of the disintegration of incident wave groups into envelope solitons.
Abstract: Nonlinear evolution of long-crested wave groups can lead to extreme interactions with coastal and marine structures. In the present study the role of nonlinear evolution in the formation of extreme run-up events on a vertical wall is investigated. To this end, the fundamental problem of interaction between non-breaking water waves and a vertical wall over constant water depth is considered. In order to simulate nonlinear wave–wall interactions, the high-order spectral method is applied to a computational domain which aims to represent a two-dimensional wave flume. Wave generation is simulated at the flume entrance by means of the additional potential concept. Through this concept, the implementation of a numerical wavemaker is applicable. In addition to computational efficiency, the adopted numerical approach enables one to consider the evolution of nonlinear waves while preserving full dispersivity. Utilizing these properties, the influence of the nonlinear wave evolution on the wave run-up can be examined for a wide range of water depths. In shallow water, it is known that nonlinear evolution of incident waves may result in extreme run-up events due to the formation of an undular bore. The present study reveals the influence of the nonlinear evolution on the wave run-up in deep-water conditions. The results suggest that extreme run-up events in deep water may occur as a result of the disintegration of incident wave groups into envelope solitons.
TL;DR: In this paper, the authors developed a method to calculate the hydraulic performance resulting from the interaction of perpendicularly impinging water waves on various types of breakwater by using the logistic sigmoid function.
TL;DR: In this article, a digital in-line holography (DIH) set-up, with a converging beam, is used to take three-dimensional (3D) velocity measurements of vortices.
Abstract: In the present paper, a digital in-line holography (DIH) set-up, with a converging beam, is used to take three-dimensional (3D) velocity measurements of vortices. The vortices are formed periodically at the edges of a submerged horizontal plate submitted to regular waves. They take the form of vortex filaments that extend from side to side of the channel. They undergo strongly three-dimensional instability mechanisms that remain very complicated to characterize experimentally. The experiments are performed in a 10 × 0.3 × 0.3 m3 wave flume. The DIH set-up is performed using a modulated laser diode emitting at the wavelength of 640 nm and a lensless CCD camera. The beam crosses the channel side to side. To reveal the flow dynamics, 30-μm hydrogen bubbles are generated at the edge of the plate to serve as tracers. Their locations are recorded on the holograms multiple times to access the dynamics of the flow. This method leads to an accuracy in the order of 100 μm on the axial location. Those measurements have been validated with stereo-PIV measurements. A very good agreement is found on time-averaged velocity fields between the two techniques.
TL;DR: In this article, the authors used an energy focusing technique to investigate the effect of wave steepness on the focusing process and found that the initial steepness of the wave wave significantly affects the energy loss.
TL;DR: In this article, a new analytical expression for calculating the wave force on a composite bucket foundation is obtained based on the diffraction theory, which is accurately derived by assigning reasonable boundary conditions.
Abstract: A new analytical expression for calculating the wave force on a composite bucket foundation is obtained. Based on the diffraction theory, the analytical solution of the wave pressure and the wave force on the composite bucket foundation is accurately derived by assigning reasonable boundary conditions. Experiments for the wave pressure on the bucket foundation with a scale of 1:60 under different wave conditions in the wave flume are designed and conducted. The analytical results agree well with the experimental data, and the theoretical approach can accurately predict the wave force on the large-scale structures. The wave pressure distribution on the composite bucket foundation is presented and the influence of the wave height, the water depth and the wave period on the wave force on the composite bucket foundation is investigated. This study provides a quite accurate method to calculate the wave force on a composite bucket foundation, which gives a good framework for future studies of the wave force on other large-scale structures with complex boundaries.