Search results for " shallow water"

Shallow water rogue wavetrains in nonlinear optical fibers

2013

International audience; In addition to deep-water rogue waves which develop from the modulation instability of an optical CW, wave propagation in optical fibers may also produce shallow water rogue waves. These extreme wave events are generated in the modulationally stable normal dispersion regime. A suitable phase or frequency modulation of a CW laser leads to chirp-free and flat-top pulses or flaticons which exhibit a stable self-similar evolution. Upon collision, flaticons at different carrier frequencies, which may also occur in wavelength division multiplexed transmission systems, merge into a single, high-intensity, temporally and spatially localized rogue pulse.

Anisotropic potential of velocity fields in real fluids: Application to the MAST solution of shallow water equations

2013

In the present paper it is first shown that, due to their structure, the general governing equations of uncompressible real fluids can be regarded as an "anisotropic" potential flow problem and closed streamlines cannot occur at any time. For a discretized velocity field, a fast iterative procedure is proposed to order the computational elements at the beginning of each time level, allowing a sequential solution element by element of the advection problem. Some closed circuits could appear due to the discretization error and the elements involved in these circuits could not be ordered. We prove in the paper that the total flux of these not ordered elements goes to zero by refining the compu…

On the Multipeakon Dissipative Behavior of the Modified Coupled Camassa-Holm Model for Shallow Water System

2013

Published version of an article in the journal: Mathematical Problems in Engineering. Also available from the publisher at: http://dx.doi.org/10.1155/2013/107450 Open Access This paper investigates the multipeakon dissipative behavior of the modified coupled two-component Camassa-Holm system arisen from shallow water waves moving. To tackle this problem, we convert the original partial differential equations into a set of new differential equations by using skillfully defined characteristic and variables. Such treatment allows for the construction of the multipeakon solutions for the system. The peakon-antipeakon collisions as well as the dissipative behavior (energy loss) after wave breaki…

Simple absorbing layer conditions for shallow wave simulations with Smoothed Particle Hydrodynamics

2013

Abstract We study and implement a simple method, based on the Perfectly Matched Layer approach, to treat non reflecting boundary conditions with the Smoothed Particles Hydrodynamics numerical algorithm. The method is based on the concept of physical damping operating on a fictitious layer added to the computational domain. The method works for both 1D and 2D cases, but here we illustrate it in the case of 1D and 2D time dependent shallow waves propagating in a finite domain.

Well-Balanced Adaptive Mesh Refinement for shallow water flows

2014

Well-balanced shock capturing (WBSC) schemes constitute nowadays the state of the art in the numerical simulation of shallow water flows. They allow to accurately represent discontinuous behavior, known to occur due to the non-linear hyperbolic nature of the shallow water system, and, at the same time, numerically maintain stationary solutions. In situations of practical interest, these schemes often need to be combined with some kind of adaptivity, in order to speed up computing times. In this paper we discuss what ingredients need to be modified in a block-structured AMR technique in order to ensure that, when combined with a WBSC scheme, the so-called 'water at rest' stationary solutions…

Cyclostratigraphy and high-frequency carbon isotope fluctuations in Upper Cretaceous shallow-water carbonates, southern Italy

2002

A detailed carbon isotope study has been carried out on a Santonian (Upper Cretaceous) carbonate platform succession that crops out at Monte Sant'Erasmo (southern Italy). Previous centimetre-scale studies on this succession have shown that high-frequency eustatic changes, resulting from the Earth's orbital fluctuations, controlled the hierarchical organization of the depositional and early diagenetic features in elementary cycles, bundles (groups of three to five elementary cycles) and superbundles (groups of three or four bundles). The elementary cycles, which correspond to single beds, suggest a control caused by Earth's precession; the bundles and superbundles record the short ( 100 kyr)…

CAN HALOPHILA STIPULACEA OUTCOMPETE CYMODOCEA NODOSA? A CASE STUDY OF A MEDITERRANEAN SHALLOW WATER HABITAT

2022

The tropical seagrass Halophila stipulacea (Forsskål) Ascherson entered the Mediterranean Sea through the Suez Canal more than 100 years ago. In the coastal-marine ecosystems the spatial niche of H. stipulacea is often overlapped with that of native Mediterranean Sea seagrasses and therefore it might out-compete them. On the basis of previous observations, we monitored for one year a Southern Mediterranean shallow water habitat (North-Western Sicily Island, Italy, Southern Mediterranean Sea), where H. stipulacea co-occurred with the native seagrass Cymodocea nodosa (Ucria) Ascherson. In this paper we compare sites with (impacted sites) and without H. stipulacea (non-impacted sites) to analy…

Filtration pressure by bivalves affects the trophic conditions in Mediterranean shallow ecosystems

2009

Bivalve filtration may control the amount of seston in coastal waters, reducing local euthrophication and keeping degrading phenomena like hypoxia and anthropogenic pollution under control. Two Sicilian brackish-marine ponds (Ganzirri and Faro) present us with the opportunity to gain data on the effect of bivalve filtration on the amount of particulate organic matter in the field. The cultivation of bivalves has been carried out in both of the ponds since the early 1990s but stopped in Ganzirri in 1995.We tested whether the cessation of bivalve cultivation influenced features of organic matter available to suspension feeders (total suspended matter, its inorganic and organic fractions, chlo…

Linking the effects of the Global Change to biodiversity and ecosystem services in shallow waters

2010

The genus Ruppia L. (Ruppiaceae) in the Mediterranean region: An overview

2015

Abstract This paper reviews the current knowledge on the diversity, distribution and ecology of the genus Ruppia L. in the Mediterranean region. The genus Ruppia, a cosmopolitan aquatic plant complex, is generally restricted to shallow waters such as coastal lagoons and brackish habitats characterized by fine sediments and high salinity fluctuations. In these habitats Ruppia meadows play an important structural and functional role. Molecular analyses revealed the presence of 16 haplotypes in the Mediterranean region, one corresponding to Ruppia maritima L., and the others to various morphological forms of Ruppia cirrhosa (Petagna) Grande, all together referred to as the “R. cirrhosa s.l. co…