Showing papers on "Wave flume published in 2013"
TL;DR: In this article, the diffusion-based smoothing algorithm of Lind et al. has been applied to body-water slam and wave-body impact problems and discover that temporal pressure noise can occur for these applications (while spatial noise is effectively eliminated).
199 citations
TL;DR: In this paper, the effects of Posidonia oceanica meadows on wave height damping and on the wave induced velocities were evaluated in the large wave flume of CIEM in Barcelona.
106 citations
TL;DR: In this article, a semi-unsteady, half wave-cycle concept is proposed for cross-shore sand transport under wave-dominated conditions, with bed shear stress as the main forcing parameter.
87 citations
TL;DR: In this article, a 2D semi-coupled model PORO-WSSI 2D (also referred as FSSI-CAS 2D) for the Fluid-Structure-Seabed Interaction (FSSI) has been developed by employing RANS equations for wave motion in fluid domain, VARAN equations for porous flow in porous structures; and taking the dynamic Biot's equations (known as " u − p " approximation) for soil as the governing equations.
65 citations
TL;DR: In this paper, a numerical model of wave-induced sand transport is presented, which includes the effects of the free surface on the bottom boundary layer, and with these effects and turbulence damping by sediment included, the model yields good reproductions of the vertical profile of the horizontal (mean) velocities, as well as transport rates of both fine and medium sized sediment.
Abstract: Recent large-scale wave flume experiments on sheet-flow sediment transport beneath Stokes waves show more onshore-directed sediment transport than earlier sheet-flow experiments in oscillating flow tunnels. For fine sand, this extends to a reversal from offshore- (tunnels) to onshore (flumes)-directed transport. A remarkable hydrodynamic mechanism present in flumes (with free water surface), but not in tunnels (rigid lid), is the generation of progressive wave streaming, an onshore wave boundary layer current. This article investigates whether this streaming is the full explanation of the observed differences in transport. In this article, we present a numerical model of wave-induced sand transport that includes the effects of the free surface on the bottom boundary layer. With these effects and turbulence damping by sediment included, our model yields good reproductions of the vertical profile of the horizontal (mean) velocities, as well as transport rates of both fine and medium sized sediment. Similar to the measurements, the model reveals the reversal of transport direction by free surface effects for fine sand. A numerical investigation of the relative importance of the various free surface effects shows that progressive wave streaming indeed contributes substantially to increased onshore transport rates. However, especially for fine sands, horizontal gradients in sediment advection in the horizontally nonuniform flow field also are found to contribute significantly. We therefore conclude that not only streaming, but also inhomogeneous sediment advection should be considered in formulas of wave-induced sediment transport applied in morphodynamic modeling. We propose a variable time-scale parameter to account for these effects.
59 citations
TL;DR: A semi-implicit shallow water and Boussinesq model has been developed to account for random wave breaking, impact and overtopping of steep sea walls including recurves.
57 citations
TL;DR: In this article, the performance of full-scale light-frame wood walls subjected to wave loading was examined using the Large Wave Flume of the Network for Earthquake Engineering (NEES) Tsunami Facility at Oregon State University.
Abstract: The performance of full-scale light-frame wood walls subjected to wave loading was examined using the Large Wave Flume of the Network for Earthquake Engineering (NEES) Tsunami Facility at Oregon State University. The hydrodynamic conditions (water level and bore speed) and structural response (horizontal force, pressure, and deflection) were observed for a range of incident tsunami heights and for several wood wall framing configurations. The walls were tested at the same cross-shore location with a dry-bed condition. For each tsunami wave height tested, the force and pressure profiles showed a transient peak force followed by a period of sustained quasi-static force. The ratio of the transient force to quasi-static force was 2.2. These experimental values were compared with the predicted values using the linear momentum equation, and it was found that the equation predicted the measured forces on the vertical wall within an accuracy of approximately 20% without using a momentum correction coeffic...
53 citations
TL;DR: In this paper, a linear experimental relation between free-stream asymmetry to skewness ratio and bottom velocity skewwness is established, and a theoretical linear relationship is discussed, which predicts the phase lead of the bottom velocity.
Abstract: [1] An experimental study on a physical model of a beach in a two-dimensional wave flume was designed to investigate velocity nonlinearities in the wave boundary layer. The cross-shore velocity was measured in the surf zone along a vertical profile every 3mm from free-stream elevation down to the still bed level. The skewness and the asymmetry of the phase averaged velocity were computed at each elevation. Observations indicate that the free-stream asymmetry transforms into bottom velocity skewness. A linear experimental relation between free-stream asymmetry to skewness ratio and bottom skewness to free-stream skewness ratio is established. A theoretical linear relationship is discussed, which predicts the phase lead of the bottom velocity. This phase lead is also determined by Fourier analyzing the velocity time series. The first two Fourier components yield the same phase lead at the bed that is found to be about 30° and nearly constant over all the experiments made.
39 citations
TL;DR: In this paper, a semi-coupled 3D numerical model for fluid-structures-seabed-interaction is developed, in which the dynamic Biot's equation known as u-p approximation and modified Navier-Stokes equation are respectively adopted as the governing equation in the soil submodel and the wave sub-model.
37 citations
TL;DR: In this article, a series of laboratory observations undertaken in a purpose-built wave flume was used to simulate a range of realistic ocean spectra evolving over a number of mild bed slopes (m ).
37 citations
TL;DR: In this article, a series of experiments have been carried out in the large wave flume (LWF) at Oregon State University to quantify tsunami bore forces on structures and the resulting forces and pressures on the wall were measured.
Abstract: A series of experiments have been carried out in the large wave flume (LWF) at Oregon State University to quantify tsunami bore forces on structures. These tests included “offshore” solitary waves, with heights up to 1.3 m, that traveled over a flat bottom, up a sloping beach, and breaking onto a flat reef. Standing water depths on the reef varied from 0.05 m to 0.3 m. Resulting bores on the reef measured up to approximately 0.8 m. After propagating along the reef, the bores struck a vertical wall. The resulting forces and pressures on the wall were measured. The test setup in the LWF is described, and the experimental results are reported. The results include forces and pressure distributions. Results show that the bores propagated with a Froude number of approximately 2 and that the forces follow Froude scaling. Finally, a design formula for the maximum impact force is given. The formula is shown to be an improvement over existing formulas found in the literature.
TL;DR: In this paper, the evolution of wind-generated water waves in a 5m-long wind wave flume facility was investigated using appropriate dimensionless parameters and quantitative comparison with the results accumulated in field measurements and in larger laboratory facilities was performed.
Abstract: Detailed investigation of wind-generated water waves in a 5-m-long wind wave flume facility is reported. Careful measurements were carried out at a large number of locations along the test section and at numerous airflow rates. The evolution of the wind wave field was investigated using appropriate dimensionless parameters. When possible, quantitative comparison with the results accumulated in field measurements and in larger laboratory facilities was performed. Particular attention was given to the evolution of wave frequency spectra along the tank, distinguishing between the frequency domain around the spectral peak and the highfrequency tail of the spectrum. Notable similarity between the parameters of the evolving wind wave field in the present facility and in field measurements was observed.
TL;DR: In this article, a simple and useful formula to predict wave transmission for a common type of floating breakwater (FB), supplied with two lateral vertical vertical plates protruding downward, named π-type FB, was defined.
Abstract: The aim of this paper is to define a simple and useful formula to predict wave transmission for a common type of floating breakwater (FB), supplied with two lateral vertical plates protruding downward, named π-type FB. Eight different models, with mass varying from 16 to 76 kg, anchored with chains, have been tested in the wave flume of the Maritime Laboratory of Padova University, under irregular wave conditions. Water elevation in front and behind the structure has been measured with two arrays of four wave gauges. Our starting point for the prediction of wave transmission was the classical relationship established by Macagno in 1954. His relationship was derived for a box-type fixed breakwater assuming irrotational flow. Consequently, he significantly underestimated transmission for short waves and large drafts. This paper proposes an empirical modification of his relationship to properly fit the experimental results and a standardized plotting system of the transmission coefficient, based on a...
TL;DR: In this article, an innovative large scale experimental program is applied to develop runup equations for long propagating waves using a pneumatic generator with a controlled valve system, capable of exchanging large volumes of water with the propagation flume.
TL;DR: In this article, the authors present the wave energy resource assessment having in view the construction of an OWC (oscillating water column) to be integrated into a new breakwater at the mouth of the Douro River in Porto (northern Portugal).
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TL;DR: Ancyclopedic article covering shallow water wave models used in oceanography and atmospheric science.
Abstract: Encyclopedic article covering shallow water wave models used in oceanography and atmospheric science. Sections: Definition of the Subject; Introduction and Historical Perspective; Completely Integrable Shallow Water Wave Equations; Shallow Water Wave Equations of Geophysical Fluid Dynamics; Computation of Solitary Wave Solutions; Numerical Methods; Water Wave Experiments and Observations; Future Directions, and Bibliography.
TL;DR: In this article, the effects of bed-form roughness on coastal wave processes were investigated on a fringing reef model in a 104m long and 4.6m high flume at Oregon State University.
TL;DR: In this paper, a semicircular breakwater model with rectangular perforations and with truncated wave screen(s) of different porosities has been developed, which could act as an anti-reflection wave barrier, providing wave protection to coastal and marine infrastructures.
TL;DR: In this paper, the authors explore possibilities to apply TLS-based range measurements of water waves in the new Delta Flume facility and investigate the influencing parameters on TLS based range measurements from water waves.
Abstract: Currently a new wave flume for hydraulic experiments near to prototype scale is under construction at Deltares. In the flume, modern measurement equipment will be installed. One of the potential sensor techniques is Terrestrial Laser Scanner (TLS) based range measurements of water waves. TLS range measurements are a very fast and accurate method for solid surfaces, providing temporal and spatial high resolution profile measurements. The conditions under which measurements of water surfaces with TLS are possible are however less well understood. The main objective of this work is to explore possibilities to apply TLS based range measurements of water waves in the new Delta Flume facility. Hence, influencing parameters on TLS based range measurements from water waves in the laboratory are identified from literature. The influencing parameters are further investigated in a test featuring the SICK LMS 511 and measuring the water surface in the 50 m TU Delft wave flume. Analysis of the results provides an insight into the possibilities and potential problems of the new measurement method. The obtained profile measurements from a originally straight still water surface showed a tendency to bend upwards at the side of the profile. For that reason a surface correction method based on the refraction of the laser beam when entering the water is elaborated. This method is part of the derived wave field reconstruction method. Finally, an optimized water wave measurement set-up for the new Delta Flume proposed.
TL;DR: In this paper, an enhanced smoothed particle hydrodynamics (SPH) method and the traditional non-breaking nonlinear model Tunami-N2 were used to simulate the wave propagation, breaking, impact on structure and the reform and breaking processes of wave rundown.
Abstract: . Accurate predictions of wave run-up and run-down are important for coastal impact assessment of relatively long waves such as tsunami or storm waves. Wave run-up is, however, a complex process involving nonlinear build-up of the wave front, intensive wave breaking and strong turbulent flow, making the numerical approximation challenging. Recent advanced modelling methodologies could help to overcome these numerical challenges. For a demonstration, we study run-up of non-breaking and breaking solitary waves on a vertical wall using two methods, an enhanced smoothed particle hydrodynamics (SPH) method and the traditional non-breaking nonlinear model Tunami-N2. The Tunami-N2 model fails to capture the evolution of steep waves at the proximity of breaking that was observed in the experiments. Whereas the SPH method successfully simulates the wave propagation, breaking, impact on structure and the reform and breaking processes of wave run-down. The study also indicates that inadequate approximation of the wave breaking could lead to significant under-predictions of wave height and impact pressure on structures. The SPH model shows potential applications for accurate impact assessments of wave run-up on to coastal structures.
01 Jan 2013
TL;DR: In this paper, a two-dimensional numerical model based on the SOLA-VOF method has been developed in order to investigate the wave interaction with fixed submerged breakwater, which can simulate time series water surface profiles, water particle velocity field, VOF function F, pressure around a breakwater.
Abstract: Experimental studies are carried out in a two-dimensional wave flume (21.3 m long, 0.76 m wide and 0.74 m deep) to investigate the performance of rectangular type submerged breakwater. A set of experiments are carried out at 50 cm still water depth with fixed submerged breakwaters of three different heights (30 cm, 35 cm and 40 cm) for five different wave periods (1.5 sec, 1.6 sec, 1.7 sec, 1.8 sec and 2.0 sec) in the same wave flume. For fifteen run conditions, water surface elevations are collected at six different locations both in front of and behind the breakwater. Also the type of wave breaking and position of wave breaking are simultaneously recorded with a digital video camera. Effects of breakwater height and length along the wave direction on wave height reduction are analyzed. It is found that both the relative structure height (hs/h) and relative breakwater width (B/L) have strong influence in reducing transmitted wave height. Experimental analysis prevails that the reduction of transmitted wave height are 50%, 58% and 68% for relative structure height (hs/h) of 0.6, 0.7 and 0.8 respectively, for a particular value of relative breakwater width (B/L =0.35). Also, the reduction of transmitted wave height is 32% and 50% for relative breakwater width (B/L) of 0.25 and 0.4 respectively, for a particular value of relative structure height (hs/h =0.6). A two-dimensional numerical model based on the SOLA-VOF method has been developed in this study to investigate the wave interaction with fixed submerged breakwater. The developed model can simulate time series water surface profiles, water particle velocity field, VOF function F, pressure around a breakwater. The water surface profiles and wave breaking positions in various wave conditions simulated by the developed numerical model show good agreement with the experimentally measured values. The numerical model developed in this study is expected to serve as tool to analyze wave deformation due to submerged breakwater and will be important for designing submerged breakwater as a coastal protection measure.
TL;DR: In this paper, the authors investigated the impact of low-frequency tidal cycles on the evolution and internal structure of modern bioclastic beach ridges in a macrotidal chenier plain surveyed with ground-penetrating radar.
Abstract: Beach ridges in macrotidal environments experience strong multi-annual to multi-decennial fluctuations of tidal inundation. The duration of tide flooding directly controls the duration of sediment reworking by waves, and thus the ridge dynamics. Flume modelling was used to investigate the impact of low-frequency tidal cycles on beach ridge evolution and internal architecture. The experiment was performed using natural bioclastic sediment, constant wave parameters and low-frequency variations of the mean water level. The morphological response of the beach ridge to water level fluctuations and the preservation of sedimentary structures were monitored by using side-view and plan-view photographs. Results were compared with the internal architecture of modern bioclastic beach ridges in a macrotidal chenier plain (Mont St. Michel Bay, France) surveyed with ground-penetrating radar. The experimentally obtained morphologies and internal structures matched those observed in the field, and the three ridge development stages identified in ground-penetrating radar profiles (early transgressive, late transgressive and progradational) were modelled successfully. Flume experiments indicate that flat bioclastic shapes play a key role in sediment sorting in the breaker zone, and in sediment layering in the beach and washover fans. Water level controls washover geometry, beach ridge evolution and internal structure. Low water levels allow beach ridge stabilization and sediment accumulation lower on tidal flats. During subsequent water level rise, accumulated sediment becomes available for deposition of new washover units and for bayward extension of the beach ridges. In the field, low-frequency water level fluctuations are related to the 4·4 year and 18·6 year tidal cycles. Experimental results suggest that these cycles may represent the underlying factor in the evolution of the macrotidal chenier coast at the multi-decadal to centennial time scale.
TL;DR: In this article, a two-dimensional Reynolds-averaged Navier-Stokes model is used to directly assess the predictive power of near-bed sediment transport models by reproducing measurements obtained in large-scale wave flume experiments.
Abstract: [1] Parameterizations of near-bed sediment processes are commonly associated with the poor predictive skill of coastal sediment transport models. We implement a two-dimensional Reynolds-averaged Navier-Stokes model to directly assess these parameterizations by reproducing measurements obtained in large-scale wave flume experiments. A sediment transport model has been coupled to wave hydrodynamics and turbulence, and numerical experiments provide temporal and spatial variations of free surface, flow velocity, sediment concentration, and turbulence quantities. Model-data comparisons enable the direct assessment of how key suspension processes are represented and of the inherent variability of the sediment transport model. We focus on the different processes occurring above rippled beds versus dynamically flat beds. Numerical results show that increasing roughness alone is not sufficient to have good predictive capability above steep ripples. Some parameterization of the vortex entrainment process is necessary and a simple modification, which leads to constant sediment diffusivity above steep-rippled beds, is sufficient to obtain good predictions of wave-averaged suspended concentrations. Model-data comparisons for the turbulent kinetic energy are also presented and highlight the need to account for the effect of vortex entrainment on near-bed turbulence and transfer of momentum.
TL;DR: In this paper, a 2D Lagrangian numerical wave model is presented and validated against a set of physical wave-flume experiments on interaction of tsunami waves with a sloping beach.
TL;DR: In this article, the relationship between the acoustic noise energy and losses of surface wave energy during breaking and acoustic noise emission was investigated in a large wave channel and it was found that the ratio of acoustic noise generated during wave breaking to the energy dissipation of single plunging breakers with heights of 1.6-2.8m were in the 10−9-10−8 range and was in reasonable agreement with the results of some previous experiments performed for smaller scales of breaking wave.
01 Jan 2013
TL;DR: In this article, physical experiments were performed in a two-dimensional wave flume to investigate the hydraulic and structural performance of a SFT model by generating regular waves of different heights and periods under various conditions of buoyancy to weight ratio (BWR) and water depth as well.
Abstract: In this study, physical experiments were performed in a two-dimensional wave flume to investigate the hydraulic and structural performance of a SFT model. The experiments were made by generating regular waves of different heights and periods under various conditions of buoyancy to weight ratio (BWR) and water depth as well. Through the analysis of the experimental data, it was clarified that the sway and heave motions of the tunnel body linearly increased with wave height and period. In contrast, the roll motion was rather insignificant unless wave height and period were comparatively large as the design wave. Similarly proportional relationship with respect to wave height and period was obtained in case of the maximum tensile force acting on the tension legs and the wave loads on the tunnel body. Regarding the change of water depth or BWR conditions, generally decreasing trend was obtained according to increase of water depth but decrease of BWR for both of the magnitudes of structural behaviors or wave loadings on the SFT structure.
TL;DR: In this article, an experimental study performed in the Large Wave Flume (GWK), Hannover, Germany, focused on the influence of the asymmetry caused by the non-linear deformation of incident waves on their runup on a plane beach.
Abstract: Didenkulova, I., Denissenko, P., Rodin, A. and Pelinovsky, E., 2013. Effect of asymmetry of incident wave on the maximum runup height. In: Conley, D.C., Masselink, G., Russell, P.E. and O’Hare, T.J. (eds.), Proceedings 12 th International Coastal Symposium (Plymouth, England), Journal of Coastal Research, Special Issue No. 65, pp. 207212, ISSN 0749-0208. Shoaling and runup of long waves on a beach form a classical task for coastal oceanography and engineering. Though many empirical and theoretical formulae have been developed in this field, most of them are targeted to typical waves and situations, while the greatest hazard is caused by extreme events, such as, for example, extreme storms and catastrophic tsunamis. From this point of view it was shown theoretically that one of the most important parameters which influence the wave runup height is the steepness of the incident wave front and the asymmetry of the incident wave. It helped to provide a simple explanation to the extreme runup observed during the catastrophic 2004 Indonesian tsunami event. However, the theoretical results were obtained under many assumptions (ideal fluid, no wave breaking, no bottom friction) and have not been validated. Here we present an experimental study performed in the Large Wave Flume (GWK), Hannover, Germany, which is focused on the influence of the asymmetry caused by the non-linear deformation of incident waves on their runup on a plane beach. The series of experiments are aimed to validate the theoretical formulae for runup height of asymmetric waves. Obtained results are in a good agreement with theoretical predictions and corresponding formulae are recommended to be considered in wave forecasts.
TL;DR: In this paper, the effect of an emergent vegetation (i.e., Phragmistes Australis) on wave attenuation and wave kinematics is investigated. But the authors focus on wave propagation.
Abstract: Akgul, M.A., Yilmazer, D., Oguz, E., Kabdasli, M.S., Yagci, O., 2013. The effect of an emergent vegetation (i.e. Phragmistes Australis) on wave attenuation and wave kinematics Coastal vegetation acts as a natural barrier at many coastal zones, protecting the landside against wave effects and coastal erosion. It is known that coastal vegetation affects wave properties, and studies regarding this topic have been made in a wide variety, mostly focusing on wave attenuation. In this study, laboratory experiments have been conducted in a wave basin to inspect the effect of an emergent vegetation on wave attenuation, wave transformation and wave kinematics. A blank area is present along the reed field, which enables energy transformation during wave propagation. Three different regular waves have been sent to a natural reed field, and wave heights and kinematics have been measured around the structure. The results indicate that crest-parallel energy transmission takes place as the waves propagate along ...
TL;DR: Aristodemo et al. as mentioned in this paper analyzed the in-line and transverse forces for a bottom-mounted submarine pipeline subjected to periodic motions characterized by non-linear Stokes and cnoidal waves, and also with a superimposed positive current.
Abstract: Aristodemo, F., Tomasicchio, G.R. and Veltri, P., 2013. Wave and current forces at a bottom-mounted submarine pipeline. In: Conley, D.C., Masselink, G., Russell, P.E. and O’Hare, T.J. (eds.), Proceedings 12 th International Coastal Symposium (Plymouth, England), Journal of Coastal Research, Special Issue No. 65, pp. 153-158, ISSN 0749-0208. The present work deals with the analysis of in-line and transverse forces for a bottom-mounted slender pipeline subjected to periodic motions characterized by non-linear Stokes and cnoidal waves, and also with a superimposed positive current. Full-scale laboratory tests were conducted in the large wave flume of CSMI at Padua, Italy, and characterized by a longitudinal vertical wall which was built in the flume to create two separate channels where simultaneous measurements of pressures, velocities and surface elevations were performed. The experimental dataset was defined by 39 tests with periodic waves using a smoother cylinder, 14 tests with periodic waves using a rougher cylinder and 11 tests with periodic waves plus currents, leading to a Keulegan-Carpenter number ranging from 4 to 13. The hydrodynamic coefficients of Morison and transverse force models were deduced from the time records of kinematics and pressures at the cylinder through the evaluation of the performances of time and frequency domain techniques such as the ordinary and the weighted least squares. The comparisons between experimental and calculated non-linear forces in terms of peaks, associated phase shifts and spectral densities show acceptable accuracy as regards the Morison force components and a poor estimation of the vertical forces.
15 Feb 2013
TL;DR: In this article, two numerical modeling tools have been developed and step by step validated, firstly on small scale flume data of wave boundary layer flow over fixed beds, subsequently on large scale flow data of sand transport rates and flow velocities above mobile beds, and finally on measurements of bed erosion.
Abstract: In the near-shore zone, energetic sea waves generate sheet-flow sand transport. In present day coastal models, wave-induced sheet-flow sand transport rates are usually predicted with semi-empirical transport formulas, based on extensive research on this phenomenon in oscillatory flow tunnels. However, recent sheet-flow experiments in large scale wave flumes, with progressive waves instead of oscillatory flow, have shown rather different results compared to the earlier tunnel experiments, namely significantly increased sand transport in onshore direction.
This study investigates in detail how progressive waves affect the wave-induced bottom boundary layer flow, the sand transport rates and the behavior of the sheet-flow layer. Hereto, two numerical modeling tools have been developed and step by step validated, firstly on small scale flume data of wave boundary layer flow over fixed beds, subsequently on large scale flume data of sand transport rates and flow velocities above mobile beds, and finally on measurements of bed erosion. The models have been applied in a numerical parameter study to quantify the importance of various progressive wave effects over a range of wave and bed conditions. Thus, it was found how two competing streaming mechanisms, respectively the onshore directed progressive wave streaming and the offshore directed non-linear wave shape steaming, determine the wave-averaged current profile. Furthermore, it was found that for larger sand grains, progressive wave streaming is the major contributor to the increased onshore transport. However, for finer grains, also an alternating convergence and divergence in horizontal sediment advection contributes increasingly with decreasing grain size.
The main result of this study is a detailed insight in how progressive wave effects contribute to sand transport. Next, parameterizations have been developed from the numerical results. These parameterizations form useful building blocks to improve practical sand transport formulas, which will contribute to better predictions of the coastal morphology in engineering practice.