1,721,170 research outputs found
A modal decomposition method for the analysis of long waves amplification at coastal areas
No full textThis paper presents a model for the evaluation of long waves amplification at coastal areas, based on a modal decomposition method. It is able of modelling the growth and the decay of the natural modes of the area under investigation, and their contribution to the total wave field. The model is an improvement of that developed by Bellotti et al. (2012b), that was able of calculating the frequencies and the shapes of the natural modes, but not their amplification under the action of forcing waves. Three test cases are used for the validation and to show the capabilities of the model. The first considers the long waves resonance into a long and narrow harbour/bay over a constant water depth. It is a case for which a high degree of wave trapping into the semi-enclosed coastal area is induced by the specific shape of the coastline. The second test deals with the propagation of a group of edge waves along a straight coast with a constant sloping bottom, generated in proximity of the shoreline by a special wave maker. The model in this case properly evaluates what are the edge waves modes that contribute to the total wave field. The third case involves the interaction of a solitary wave with a conical island, for which laboratory data are available. In this test a low degree of trapping exists, but it is interesting for the present aims as the propagation of the waves around the island is expected to occur under the form of wave modes partially trapped by the bathymetry i.e. edge waves, excited by the transient wave arriving from offshore. On the basis of the tests results it is shown what is the role of the more relevant natural modes in the formation of the total surface elevation
A preliminary study on wave shoaling and evolution up to the shoreline by means of a Boussinesq-type model.
No full textWave forces on vertical caissons with retreated wall: A first experimental insight
No full textThis paper presents a physical model study of wave induced forces on a composite vertical breakwater, where the crown wave wall is retreated with respect to the front face of the caisson. Four different configurations (one flushed wall and three retreated wall configurations) have been tested under regular wave conditions, aiming at providing a first experimental insight on the increase/reduction of the wave loads acting on the structure. The analysis of the experimental results allows to describe the basic phenomena involved and to identify the physical/geometrical drivers, which are expected to play a role on the force increase/reduction factor. Thus, detailed processing of both forces/moments (synchronous analysis) and pressures (asynchronous analysis) on the whole structure, the wall and the caisson trunk, together with the analysis of reflection coefficients as a function of the wall position, are presented and discussed in the paper. The experimental evidences suggest that, at least for the four configurations tested, the global forces acting on the caisson vary significantly depending on the wall position, resulting in a reduction between 5% and 31% for high energy sea states. A similar behavior is found considering the global moments. Furthermore, the synchronous analysis of the forces highlighted that the physical/geometrical drivers, identified in the present study, can have both a concordant and antithetical action among them, then resulting in increasing or decreasing, respectively, forces acting on the structure, if compared with the flushed wall configuration
Propagation of tsunamis over large areas using COMSOL
No full textThis paper presents a numerical model
based on the mild-slope equation (MSE for
short) suitable to reproduce the propagation of
small amplitude tsunamis in the off-shore field.
The model solves the governing equations in the
frequency domain and allows the reproduction of
the frequency dispersion for broad banded
spectrum sea states. The model application to
reproduce laboratory experiments and real life
tsunamis in the south Tyrrhenian sea
(Mediterranean Sea) are described, showing its
applicability to relative large geographical areas.
The proposed method is suitable to support a real
time tsunami early warning system
Contributi di storia della psichiatria
No full textContiene gli atti di un convegno sulla psichiatria lombarda del XIX secol
Laboratory experiments on wave forces on vertical breakwaters with retreated crown walls
No full textIn this paper, the preliminary results of an experimental campaign aiming at investigating the wave forces on a composite vertical breakwater are presented. Specifically, the influence of the position of the wave wall are considered. Four different retreated wall configurations have been tested under regular wave conditions aiming at providing a first experimental insight on the reduction/increase of the forces/pressures acting on the whole structure, the wall and the caisson trunk due to the wall retreat
Empirical and numerical modal analysis of coastal areas prone to tsunami risk
No full textIn this paper the Empirical Orthogonal Function (EOF) method and the k-f spectral technique are applied to extract from experimental data related to landslide-tsunamis propagating around the coast of a conical island, the wave modes that contribute to the wave field. The relevant modes are then compared with those obtained through numerical eigenanalysis of the long wave equation around the considered island. It is shown that it is possible to associate each EOF mode with some eigenvectors and the corresponding eigenfrequencies, both on the basis of the spatial shape, the wavenumber calculated along the coast and the frequency. Results confirm that landslide-generated waves propagate along the coast as trapped edge waves and the zero-th order mode is the most important
SAMMARCO, P.; DE FINIS, S.; CECIONI, C.; BELLOTTI, G.; FRANCO, L. ARPEC: A novel staggered perforated permeable caisson breakwater for wave absorption and harbor flushing. Coastal Engineering, 2021, Vol 169. https://doi.org/10.1016/j.coastaleng.2021.103971
No full textRegional downscaling of copernicus era5 wave data for coastal engineering activities and operational coastal services
Full text linkHindcasted wind and wave data, available on a coarse resolution global grid (Copernicus ERA5 dataset), are downscaled by means of the numerical model SWAN (simulating waves in the nearshore) to produce time series of wave conditions at a high resolution along the Italian coasts in the central Tyrrhenian Sea. In order to achieve the proper spatial resolution along the coast, the finite element version of the model is used. Wave data time series at the ERA5 grid are used to specify boundary conditions for the wave model at the offshore sides of the computational domain. The wind field is fed to the model to account for local wave generation. The modeled sea states are compared against the multiple wave records available in the area, in order to calibrate and validate the model. The model results are in quite good agreement with direct measurements, both in terms of wave climate and wave extremes. The results show that using the present modeling chain, it is possible to build a reliable nearshore wave parameters database with high space resolution. Such a database, once prepared for coastal areas, possibly at the national level, can be of high value for many engineering activities related to coastal area management, and can be useful to provide fundamental information for the development of operational coastal services
- …
