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We present the modeling of the main facets of turbulence diffusion, i.e., diffusion of momentum, mass, density, and heat, within the smoothed particle hydrodynamics (SPH) method. The treatment is developed considering the large eddy simulation (LES) approach and is specifically founded on the δ-LES-SPH [A. Di Mascio et al., Phys. Fluids 29, 035102 (2017)], a model characterized by a turbulence closure for the continuity equation. The novelties introduced are the modeling of the advection–diffusion equation through turbulent mass diffusivity and the modeling of the internal energy equation through heat eddy diffusivity. Moreover, a calibration for the closure term of the continuity equation is also proposed, based on the physical assumption of equivalence between turbulent mass and density diffusion rates. Three test cases are investigated. The first test regards a two-dimensional (2D) problem with splashing and wave-breaking dynamics, which is used to investigate the proposed calibration for the turbulent density diffusion term. In the second test, a 2D jet in coflow condition without gravity is studied with particular emphasis on the advection–diffusion process. The last test regards the most general condition and reproduces three-dimensional (3D) jets in crossflow conditions, in which attention is given to both the mass and heat advection–diffusion processes. The proposed methodology, which allowed us to accurately reproduce the experimental tests considered, represents a promising approach for future investigation of problems characterized by complex dynamics with turbulence and mixing involved. [ABSTRACT FROM AUTHOR]

A study of a 42-year (1979–2020) long wave time series was performed for the Mediterranean Sea to detect and quantify trends in two relevant wave parameters adopted for coastal and offshore engineering purposes: significant wave height, H s and peak period, T p. The high resolution MeteOcean Re-Analysis database by the Department of Civil, Chemical and Environmental Engineering (DICCA) was used. At yearly and seasonal scales, the trends of the mean and maximum values were detected by the Mann–Kendall test, choosing a significance level equal to 90%. The slope or increase/decrease trends in H s and T p were assessed by the Theil–Sen estimator. For the mean values of H s and T p , increasing trends were detected for the Libyan, Levantine and Aegean seas, while for the maximum values this increasing trend was observed in a large part of the Mediterranean Sea. Finally, for the different marginal seas of the Mediterranean basin, a running trend analysis was applied in order to quantify the effect of the time window in the trend detection. The obtained results can be significant for flooding and erosion control strategies, ship and port operations, design and verification of structures, installations of Wave Energy Converters, in a hot spot for climate change such as the Mediterranean basin. • Analysis of mean and maximum annual and seasonal wave trends of H s and T p in the Mediterranean Sea. • The high resolution MeteOcean re-analysis database was used. • Trend detection was performed by the Mann–Kendall test. • Trend quantification was assessed by the Theil–Sen estimator. • A running trend analysis was applied. [ABSTRACT FROM AUTHOR]

A formula is proposed to determine the maximum reference pressure at the interface of the breakwater core and filter layer, based on small-scale physical model tests. Regular and irregular waves have been considered. It is found that the maximum reference pressure at the interface of the breakwater core and filter layer depends on the level of the water surface along the breakwater seaward slope. The proposed formula is verified using large-scale model results and real-scale field observations in non-overtopping and non-breaking wave conditions; it contains a nondimensional parameter that is a function of the wavelength and width of the core at a given water depth. [ABSTRACT FROM AUTHOR]

Bathymetry changes induced by marine propeller jets on movable beds are a crucial issue in harbors, especially in the maneuvering zone. The knowledge of the scour hole and deposition mound dimensions, due to propeller jets, is important in the context of sediment management. Although the presence of waves is well known in harbor environments, propeller jet scours are usually investigated under still water conditions neglecting the effect of wave interaction. Moreover, the interaction between waves and propeller jets can also occur in mooring out of harbors. For these cases, the interaction of wave induced hydrodynamics and propeller jets is a crucial issue that is still an open and challenging problem. This paper aims to address, for the first time, the knowledge gap by investigating the influence of waves on propeller jets in unconfined conditions, which in turn can lead to alterations in scour and deposition patterns. The study relies on a specific experimental investigation. The selection of the parameters of the experimental tests is based on the results of prior analyses aimed to investigate the propeller jets induced scour and deposition in still water conditions and in the presence of a current. Hence, regular waves with different parameters (i.e. wave height and wave period) have been then reproduced in a wave flume where a propeller jet has been installed. The experimental tests aimed to get insight on the scour profiles as well as scour hole bathymetry induced by propeller jets under the influence of regular wave propagation. Numerical simulations have been also performed to investigate the effects of the wave-induced velocity acting on the propeller jets hydrodynamics. Spectral analysis has been then applied to characterize the complex scoured form and bedforms on the bathymetry configuration induced by the tested propeller jet and waves. • Experimental campaign to achieve the quasi-equilibrium state bathymetry of a marine propeller jet with the presence of a wave motion. • Morphodynamic and hydrodynamic analysis. • RANS simulations with the k − ω SST turbulence closure model. • Spectral analysis to characterize the local scour and bedforms. [ABSTRACT FROM AUTHOR]

The present paper proposes a smoothing analysis of hydraulic head data sets obtained by means of different slug tests introduced in a confined aquifer. Laboratory experiments were performed through a 3D large-scale physical model built at the University of Calabria. The hydraulic head data were obtained by a pressure transducer placed in the injection well and subjected to a processing operation to smooth out the high-frequency noise occurring in the recorded signals. The adopted smoothing techniques working in time, frequency and time-frequency domain are the Savitzky-Golay filter modeled by third-order polynomial, the Fourier Transform and two types of Wavelet Transform (Mexican hat and Morlet). The performances of the filtered time series of the hydraulic heads for different slug volumes and measurement frequencies were statistically analyzed in terms of optimal fitting of the classical Cooper’s equation. For practical purposes, the hydraulic heads smoothed by the involved techniques were used to determine the hydraulic conductivity of the aquifer. The energy contents and the frequency oscillations of the hydraulic head variations in the aquifer were exploited in the time-frequency domain by means of Wavelet Transform as well as the non-linear features of the observed hydraulic head oscillations around the theoretical Cooper’s equation. [ABSTRACT FROM AUTHOR]

This paper presents a performance evaluation of Wave Energy Converters (WECs) in terms of electricity production for domestic and public supplies of coastal towns located near hot spot areas. The study was conducted off the coast of Calabria (Southern Italy), a Mediterranean region characterized by a mild wave climate which is quite representative of mean sea states in the Mediterranean basin. The wave energy potential was assessed in deep waters by means of ECMWF wave data validated against RON buoys and UKMO data. Thirteen types of offshore WECs were considered, comparing the performances of full-scale and downscaled devices in terms of yearly and seasonal mean electricity production and operating days. Based on the domestic electricity supplies and those related to the public plants of some selected coastal cities, the number of differently sized devices was calculated in order to satisfy the above needs. To preserve the wave energy production level, the spatial arrangement of wave energy farms was determined in order to minimize possible park effects. The obtained results highlight that the occurrence of offshore WEC farms in a typical Mediterranean zone can lead to a significant number of WECs for domestic and public electricity supplies with a progressive reduction for more energetic sites. [ABSTRACT FROM AUTHOR]

This work deals with an experimental and numerical study on the horizontal and vertical hydrodynamic forces induced by solitary waves on submerged horizontal circular cylinders. Laboratory tests were performed in the wave flume of the University of Calabria. A battery of pressure transducers was mounted along the external contour of a cylinder placed at half water depth, while four wave gauges were located close to the cylinder and an ultrasonic sensor behind the paddle to measure its displacement. From the numerical viewpoint, a diffusive weakly-compressible SPH model was adopted. To prevent spurious flows near the cylindrical contour, a packing algorithm has been applied to initialize the SPH fluid particles. The acoustic components occurring in the numerical pressure field were filtered through the application of Wavelet Transform. Experimental and numerical analyses were performed in the inertia-dominated regime where these force components are more relevant than the drag and lift ones. The deviation from the fully inertia regime was highlighted in the simulations by the occurrence of a couple of asymmetric vortices behind the cylinder. The good agreement between experimental and SPH forces and kinematics at the cylinder has allowed the numerical calibration of the hydrodynamic coefficients in the Morison and transverse semi-empirical equations by different time-domain methods. For engineering purposes, we propose simple empirical formulas based on the knowledge of wave amplitude to calculate the hydrodynamic coefficients. [ABSTRACT FROM AUTHOR]

The stability of submerged rigid breakwaters subject to the action of solitary waves is here investigated by an experimental and numerical approach. Attention is paid to the features of the horizontal and vertical hydrodynamic forces which could make these marine structures unstable. The current work considers submerged barriers with square and rectangular sections and three different relative heights. Experimental tests were undertaken in a wave flume, adopting twelve pressure sensors along the external contour of the barriers in order to calculate the hydrodynamic loads. Numerical simulations were performed using the weakly-compressible δ -LES-SPH model. The aim of these simulations was to enlarge the laboratory cases in order to achieve potential critical conditions against sliding, overturning and bearing capacity of foundation. It was found that, by increasing the relative height of the breakwaters, the wave loads tended to grow, particularly for the horizontal ones. This aspect implied that the barrier with the highest relative height represents the most disadvantageous configuration for its stability. For the square barrier, the critical conditions against sliding and overturning appeared in correspondence of the highest wave amplitudes, while an effective area at the foundation/soil interface occurred starting from moderate wave amplitudes. Practical semi-empirical equations to determine the minimum safety factors as a function of wave amplitude, water depth, barrier geometry and materials were deduced. • Analysis of solitary wave-induced forces at submerged rigid barriers. • Laboratory experimental and δ -LES-SPH simulations have been performed. • The barrier with the highest relative height is the most disadvantageous configuration for its stability. • Formulas to determine the minimum safety factors against sliding and overturning have been deduced. [ABSTRACT FROM AUTHOR]

In this work, the phenomenon of wave run-up induced by solitary waves in breaking and nonbreaking conditions has been investigated. Despite several studies have been carried out to study this kind of physical process, a robust determination of solitary wave run-up on plane beaches over a wide range of wave conditions and beach slopes is still lacking. In this context, 99 laboratory tests were undertaken in the wave channel of the University of Calabria by adopting three beach slopes and three water depths. The experimental set-up was made up of four wave gauges, a pressure transducer, a velocimeter and an adjustable waterproof ramp to reproduce the plane sloping beach. Using graduated markers along the beach and a video camera, the run-up was deduced. The present experiments cover a range not extensively analyzed in literature, and specifically related to wave run-up comparable or greater than the water depth. The laboratory run-up, velocity and pressure data were validated using the IH-2VOF numerical model. Two different approaches, both for breaking and nonbreaking conditions, were used to obtain semi-analytical formulas for the wave run-up. The first approach is conventional, being based on wave non-linearity and beach slope, while the second is based on the wave energy. • Laboratory and numerical investigation on solitary wave run-up at sloping. • The calculation of the run-up has been performed as a function of the wave amplitude or the wave energy based on the Buckingham theorem. • Limits and capabilities of literature formulas have been investigation. [ABSTRACT FROM AUTHOR]

This paper deals with the development and application of a two-dimensional weakly compressible Smoothed Particle Hydrodynamics (SPH) model to study plane jets propagating into still fluid tanks and current flows. These flow processes occurring in different water bodies are here treated through an appropriate algorithm to model inlet/outlet boundary conditions which are defined by different sets of particles. SPH equations of fluid mechanics including viscous and interface stabilization terms are adopted to determine the flow field induced by the fluid interaction. Flow phenomena induced by jet injection in a water body occur in natural and anthropic environments such as pollutant discharge into reservoirs, rivers and coasts, or in several engineering applications such as marine outfalls. Three test cases with different initial configurations are simulated: injection of a jet at the top and at the bottom of a water tank, and upstream of a channel flow (coflow jet). The proposed SPH model is validated both near the jet nozzle and far from it, comparing the obtained jet trajectories, widths and velocities with other numerical approaches, laboratory experiments and analytical solutions. [ABSTRACT FROM AUTHOR]

In this paper, the large eddy simulation (LES) model introduced in the smoothed particle hydrodynamics (SPH) by Di Mascio et al. [Phys. Fluids 29, 035102 (2017)] and called δ-LES-SPH, is extended to treat multiphase flows. This is achieved by modifying the multiphase δ-SPH by Hammani et al. [Comput. Methods Appl. Mech. Eng. 368, 113189 (2020)] by switching the viscous and density diffusion constants to dynamic variables evaluated as turbulence closure terms. The equation for energy conservation is also written for the presented model. The validation is performed for two-dimensional problems, by comparison with other established SPH solvers, with a finite volume method solver based on the turbulence closure corresponding to that adopted for the Lagrangian scheme, and with experimental data. The first test case investigated is a modified Taylor–Green vortex in which the introduction of macro-bubbles of a lighter fluid phase inside the domain is considered. In the second test case, a more violent problem involving wave breaking and splashing dynamics is analyzed. In the final test, the dynamic of a sloshing problem is reproduced. An analysis of turbulence resolution is conducted by considering modeled and resolved turbulent kinetic energies, as well as viscous dissipation and turbulent viscosity dissipation. [ABSTRACT FROM AUTHOR]

The present work deals with a laboratory investigation on the wave transmission at a submerged breakwater under the action of solitary waves. Experiments were undertaken in the wave flume of the University of Calabria with the use of four resistance wave gauges placed two before and two after a rigid square barrier, adopting three different water depths. The calculation of the transmission coefficients was carried out using wave amplitudes or wave energies. To validate the latter approach, some numerical experiments were successfully performed using two different numerical models: the Lagrangian δ -LES-SPH and the Eulerian Ansys Fluent. The energy content of various waveforms involved in the interaction was analyzed in depth, also taking into account reflection, viscous effects and dissipation. For practical engineering applications, wave transmission coefficients were deduced by semi-empirical equations as a function of the wave non-linearity and the relative height of the breakwater. [ABSTRACT FROM AUTHOR]

This paper proposes a 2D diffusive weakly-compressible Smoothed Particle Hydrodynamics (SPH) model to simulate wave loads and hydraulic characteristics at perforated breakwaters. The solid boundary technique of the fixed ghost particles (Marrone et al., 2011a), based on interpolation nodes located within the fluid domain, is here extended to a multi-node approach. The proposed modeling is defined by the association of more interpolation nodes to a single solid particle in order to allow interaction with fluid particles located at different positions in the computational domain. The present enforcing is introduced with the aim of overcoming disadvantages in terms of CPU time for heavy SPH simulations in which the choice of the initial spatial resolution of the model is driven by the presence of thin structures immersed in a fluid mass such as the slotted wall of breakwaters. The present solid boundary treatment is firstly validated for a still water tank characterized by two different static levels and for a green water overtopping a fixed deck. Successively, the SPH model is applied to simulate the interaction between regular waves with fully and partially perforated breakwaters. Numerical results are successfully compared with experimental data in terms of dynamic pressures acting on the body profiles of the considered breakwater and wave reflection. [ABSTRACT FROM AUTHOR]

This paper deals with the development of a 2D weakly compressible SPH model to simulate wave pressures acting on vertical and slotted coastal structures. Attention is devoted to investigate the diffusive term in the continuity equation in order to smooth out the high-frequency numerical noise in the pressure field. A hybrid formulation based on two literature diffusive models is proposed. The interaction between regular waves with vertical and perforated breakwaters is analyzed in time, space, and frequency domain. Numerical results are compared with laboratory experiments and other diffusive SPH formulations, varying the magnitude of the adopted diffusive term. On the basis of an error analysis, the results show that the hybrid formulation gives a better agreement with the experimental data for the majority of the investigated cases. Moreover, SPH simulations highlight nonlinear trends of dynamic pressures in correspondence with geometrical singularities, such as the holes of slotted walls, due to strong pressure drops induced by the flow motion. [ABSTRACT FROM AUTHOR]

An analysis of a 40-year long wave time series was carried out in the Mediterranean basin to identify ongoing trends of three wave parameters: significant wave height, energy period and wave power. Synthetic wave data were deduced from the global atmospheric reanalysis ERA-Interim by the ECMWF. After a preliminary data examination, a trend analysis, at annual and seasonal scales, was performed on the mean and maximum values through the Mann-Kendall test. Moreover, the application of the Theil-Sen estimator allowed us to quantify the magnitude of the increase/decrease in the wave parameters. Results highlighted different behaviours between the mean and the maximum values. In general, an overall increase in the mean wave quantities was observed, particularly for the energy period, while the increase in the maximum wave parameters was limited to a few grid points. For both the mean and the maximum values, negative trends were identified in specific areas of the Mediterranean Sea, especially for the significant wave height and the wave power. The study findings could be useful for analyses linked to various activities such as coastal inundations and erosions, the design of marine structures and the identification of optimal sites for field installations of Wave Energy Converters. • A trend analysis on H s , T e and P is conducted in the Mediterranean Sea. • Trend detection is carried out through Mann-Kendall test. • Trend quantification is performed using Theil-Sen estimator. • A general increase in the mean wave quantities is observed. • The increase in the maximum wave parameters is limited to a few grid points. [ABSTRACT FROM AUTHOR]

Aristodemo, F., Tomasicchio, G.R. and Veltri, P., 2013. Wave and current forces at a bottom-mounted submarine pipeline. 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. [ABSTRACT FROM AUTHOR]

Abstract: In recent years Beach Drainage Systems (BDS) have been considered as an innovative approach to stabilize the beachface even if it still has to be proven to what extent they are effective in stabilizing the beach or causing accretion. This paper describes tests carried out at the “Grosser WellenKanal” in Hannover aimed at improving the knowledge of the hydrodynamic and morphodynamic behaviour of a beach containing a buried drainage system. Scale effects that affected previous BDS laboratory experiments are minimized by the large scale. The morphodynamic response of the undrained beach compared to a beach drained under the same type of wave action is reported. Experiments were undertaken using a set of multiple drains, up to three working simultaneously, located below the beach and at variable distances from the shoreline. The experimental program was organized in a series of tests with variable wave energy. While a positive effect was observed under low energy conditions, for medium and high energy conditions, the benefit of having the drains operative was not always clear. In any case, it was evident that any positive effect of the drains on the beachface was limited to the position of the cone of depression represented by the lowering of the hydraulic head. [Copyright &y& Elsevier]

An extensive full-scale laboratory investigation on a two-dimensional physical model of a beach drainage system (BDS) was performed at “Grosser Wellen-Kanal” of Hannover, Germany. This research deals with the hydrodynamic aspects of a beach equipped with a BDS, while the morphodynamic aspects of the study are discussed in a companion paper. Knowledge of both the hydrodynamic and the morphodynamic behaviours of a drained beach allows the definition of the main design criteria. The adopted BDS was constituted by four corrugated pipes. Several drain configurations in static and dynamic conditions were considered, paying attention to water table oscillations, drains and groundwater regime and drainage discharge induced by the system start-up. The main results indicate a rise in the unsaturated beach and the presence of a hydraulic disconnection in the groundwater–drain system. The analyses yield useful hydrodynamic information influencing the general system efficiency. [ABSTRACT FROM AUTHOR]

Abstract: The present paper proposes a numerical model to determine horizontal and vertical components of the hydrodynamic forces on a slender submarine pipeline lying at the sea bed and exposed to non-linear waves plus a current. The new model is an extension of the Wake II type model, originally proposed for sinusoidal waves (Soedigdo et al., 1999) and for combined sinusoidal waves and currents (Sabag et al., 2000), to the case of periodic or random waves, even with a superimposed current. The Wake II type model takes into account the wake effects on the kinematic field and the time variation of drag and lift hydrodynamic coefficients. The proposed extension is based on an evolutional analysis carried out for each half period of the free stream horizontal velocity at the pipeline. An analytical expression of the wake velocity is developed starting from the Navier–Stokes and the boundary layer equations. The time variation of the drag and lift hydrodynamic coefficients is obtained using a Gaussian integration of the start-up function. A reduced scale laboratory investigation in a large wave flume has been conducted in order to calibrate the empirical parameters involved in the proposed model. Different wave and current conditions have been considered and measurements of free stream horizontal velocities and dynamic pressures on a bottom-mounted pipeline have been conducted. The comparison between experimental and numerical hydrodynamic forces shows the accuracy of the new model in evaluating the time variation of peaks and phase shifts of the horizontal and vertical wave and current induced forces. [ABSTRACT FROM AUTHOR]

A laboratory and numerical investigation on the features of the horizontal and vertical hydrodynamic loads given by a solitary wave on a submerged square barrier is presented. By the experimental viewpoint, the wave forces were deduced from the records of a discrete battery of pressure sensors located along the external surface of the barrier. As regards the numerical viewpoint, simulations were performed through the SPH model presented in Di Mascio et al. (2017), in which the governing equations are written considering a turbulence closure model. The numerical simulations allowed to extend the range of analyzed cases and highlighted the regions around the submerged barrier of higher dissipation occurring during the wave-structure interaction. A good agreement between the experimental and numerical peaks of the horizontal and vertical forces was found. Afterwards, a semi-analytical scheme able to determine the horizontal loads was adopted using the speed drop factor obtained by physical tests and simulations. For practical purposes, attention was finally paid to determine the critical conditions against the sliding of the barrier. • Investigation on solitary wave-induced forces on a submerged square barrier. • The maximum vertical loads have been found relevant for stability analysis. • The speed drop factor has been determined to estimate the horizontal force. • The safety factor against the sliding of the barrier has been analyzed. [ABSTRACT FROM AUTHOR]

The present study describes an experimental and numerical investigation on the horizontal and vertical hydrodynamic forces given by solitary waves on horizontal circular cylinders placed near a rigid horizontal bed. The experimental campaign was conducted in the wave channel of the University of Calabria in which twelve pressure sensors were installed along the external surface of a cylinder located at gap-to-diameter ratios equal to 0.25 and 0.1. The numerical modeling was carried out using the open source OlaFlow model, based on the OpenFOAM solver, in order to simulate the wave forces, also extending the range of experiments. The resulting force field was defined by the dominance of the horizontal inertia force along the flow direction and by the lift force along the transversal one. The values of the hydrodynamic forces and the free stream kinematics were adopted to calibrate the hydrodynamic coefficients (drag, lift and horizontal and vertical inertia) involved in the Morison formula and in a proposed version of the transverse equation through the use of the weighted least square approach. For practical aims, semi-analytical relationships to determine the hydrodynamic coefficients as a function of wave amplitude and water depth are presented. • Experimental and numerical study of horizontal and vertical hydrodynamic forces induced by tsunami-like solitary waves on horizontal cylinders placed near a horizontal bed. • The resulting force field is characterized by the prevalence of the inertial component for the horizontal force and by the lift component for the vertical one. • A modified transverse scheme to calculate the vertical forces is proposed. • Empirical formulas to determine the hydrodynamic coefficients as a function of wave amplitude and water depth are presented. [ABSTRACT FROM AUTHOR]

The reduction of wave run-up induced by solitary waves at sloping beaches, by means of submerged barriers has been investigated. To this purpose, 198 laboratory tests were undertaken in the wave channel of the University of Calabria, by adopting three beach slopes, three water depths and square and rectangular rigid type-barriers. To make comparisons on the performance of the barriers in reducing the run-up, 99 tests were carried out considering the same experimental conditions, without the barriers. Two approaches were used to deduce the resulting solitary wave run-up in the presence of the barriers starting from the knowledge of wave parameters without them. The first approach uses the wave amplitude, whereas the second, more physically based, uses the wave energy, depending on the horizontal velocity and the wave pressure. Based on the calculation of the transmission coefficients using the dimensional analysis, the transmitted wave amplitude and energy after the barriers were deduced. Using these quantities, the recent semi-empirical formulas deduced by Casella et al. (2022) in the absence of the barriers were extended to determine the solitary wave run-up in their presence. • Analysis of solitary wave run-up on beach in the presence of submerged barriers. • The tests were compared with experiments conducted without the submerged barriers. • The run-up was deduced by semi-empirical equations using two different approaches. [ABSTRACT FROM AUTHOR]

Ciavola, P., Contestabile, P., Aristodemo, F., and Vicinanza, D., 2013. Beach sediment mixing under drained and undrained conditions. The paper describes a set of experiments undertaken at the Grosser Wellen Kanal (GWK) in Hannover on sediment mixing on a beachface exposed to the action of a buried drainage system. Experiments were performed using a set of drains (up to three working simultaneously), located at variable distance from the shoreline. Wave energy during the tests ranged from medium (0.59 m < Hs < 0.61 m) to high (0.76 m < Hs < 0.83 m). Beach profiles were measured at the end of each test. Further validation came from measurements using a grid of rods that were monitored at the same time as the beach profiles were surveyed. While some beach stabilization was observed for low energy conditions, for medium and high energy conditions the benefit of having the drains operative was not so clear. The comparison between beach profiler and rods showed good agreement regarding relative vertical accretion and erosion events. In any case, it was evident that the sedimentary effect on the beachface was confined to a narrow area above the drains. The drained area showed slightly lower values of sediment mixing under drained conditions, but evidently this factor was not important enough to trigger a widespread beach stabilization. Values of sediment mixing averaged across the whole beachface ranged between 2-4 % and 4-6 % of the breaking wave height respectively for high and medium energy wave conditions. Grain size, beach slope and drain configurations used here are fully comparable to field installations present in the literature. [ABSTRACT FROM AUTHOR]

This research describes a unique set of experiments undertaken at the Large Wave Channel (Hannover) aimed to study the morphodynamic behaviour of a beach face containing a buried drainage system. The advantage of using a large wave flume is that scale effects that affected previous laboratory experiments are minimized. This compares the response of the undrained beach under controlled wave forcing with the response of the drained one with the same wave action. Low, medium and high levels of wave energy were used for the experiments, with significant wave heights of 0.39–0.83 m and wave steepnesses between 0.004 and 0.013. Any positive effect of the drains on the beach face was confined by the position of the cone of depression in the aquifer surface. The best performance of the system was observed with two drains operating at the same time under low to moderate wave energy. [ABSTRACT FROM AUTHOR]