Optimal control for studying wave energy in hydraulic systems

A class of novel models for water waves induced by elastic deformation in the topography is developed and analyzed. The depth-averaged shallow water equations including friction terms for the water free-surface and the well-known second-order elastostatic formulation for the bed deformation have been implemented. Friction forces and water hydrostatic pressure distribution are also accounted for in this model. At the interface between the water ow and the bed topography, transfer conditions are implemented. Furthermore, a hybrid nite element/nite volume method for solving free-surface run-up ow problems over deformable beds has been proposed. The deformations in the topography have been generated by a localized force which causes propagations of the water waves with dierent amplitudes and frequencies. Two dierent methods have been proposed for the transfer of informations through the interface. The rst one is the two-mesh procedure; in this method a proper interpolation has been implemented to transfer the data between the surface nodes and the control volumes using uniform nite volume meshes. In the second method, and to avoid the interpolation at the interface, a nite volume method using non-uniform meshes has been implemented. When the shallow water waves approach the coastline they begin to transform as they enter shallow water regime. As each wave begins to experience the seabed, both run-up and overtopping occur. To solve for this, a class of stable, accurate and simple numerical model for moving wet/dry fronts in shallow water equations using the parametrization concept and the point-wise Riemann solver has been proposed. Many parameters of shallow water equations are subject to uncertainties to the inherit randomness of natural processes. To incorporate uncertain parameters into the stochastic shallow water equations, the stochastic properties of dierent parameters that are considered uncertain, namely in ow boundary condition, the bed friction coecients and the domain topography are added to the system. Development of accurate and ecient tools for uncertainty quantication in shallow water ows has been proposed and carefully examined for single-layer, two-layer - nite volume models. To further quantify the uncertainty in shallow water ows the proposed methods have been extended to multi-layer shallow water ows with mass exchange terms subject to stochastic topography, uncertain friction and viscosity coecients. Several test examples and well-established benchmark problems have been used to assess the numerical performance of the proposed models and methods. Comparisons to experimental measurements have also been carried out in this thesis. Finally, an optimal control technique for bed reconstruction has been presented as in many engineering applications this information is not entirely provided

Hydrodynamic provinces and oceanic connectivity from a transport network help designing marine reserves

Oceanic dispersal and connectivity have been identified as crucial factors for structuring marine populations and designing Marine Protected Areas (MPAs). Focusing on larval dispersal by ocean currents, we propose an approach coupling Lagrangian transport and new tools from Network Theory to characterize marine connectivity in the Mediterranean basin. Larvae of different pelagic durations and seasons are modeled as passive tracers advected in a simulated oceanic surface flow from which a network of connected areas is constructed. Hydrodynamical provinces extracted from this network are delimited by frontiers which match multi-scale oceanographic features. By examining the repeated occurrence of such boundaries, we identify the spatial scales and geographic structures that would control larval dispersal across the entire seascape. Based on these hydrodynamical units, we study novel connectivity metrics for existing reserves. Our results are discussed in the context of ocean biogeography and MPAs design, having ecological and managerial implications

The routes of the Mediterranean Sea circulation

The Mediterranean Sea is a semi-enclosed basin connected to the Atlantic Ocean through the narrow and shallow Strait of Gibraltar and further subdivided in two different sub-basins, the Eastern Mediterranean and the Western Mediterranean, connected through the Stait of Sicily. On annual basis, a net heat budget of −7 W/m2, combined with exceeding evaporation over precipation and runoff together with wind stress, is responsible for the antiestuarine character of the zonal thermoaline circulation. The outflow at Gibraltar Strait is mainly composed of Levantine Intermediate Water (LIW) and deep water masses formed in the Western Mediterranean Sea. The aim of this thesis is to validate and quantitatively assess the main routes of water masses composing the ouflow at Gibraltar Strait, using for the first time in the Mediterranean Sea a lagrangian interpretation of the eulerian velocity field produced from an eddy-resolving reanalysis dataset, spanning from 2000 to 2012. A lagrangian model named Ariane is used to map out three-dimensional trajectories in order to describe the pathways of water mass transport from the Strait of Sicily, the Gulf of Lyon and the Northern Tyrrhenian Sea to the Gibraltar Strait. Numerical experiments were carried out by seeding millions of particles in the Strait of Gibraltar and following them backwards in time to track the origins of water masses and transport exchanged between the different sections of the Mediterranean. Finally, the main routes of the intermediate and deep water masses are reconstructed from virtual particles trajectories, which highlight the role of the Western Mediterranean Deep Water (WMDW) as the main contributor to the Gibraltar Strait outflow. For the first time, the quantitative description of the flow of water masses coming from the Eastern Mediterranean towards the Gibraltar Strait is provided and a new route that directly links the Northern Tyrrhenian Sea to Gibralatr Strait has been detected

Submesoscale dynamics in the Western Mediterranean Sea

Thesis Tutor: Romualdo Romero March.-- Doctor of Philosophy in Physics, University of the Balearic Islands.The transition from mesoscale to submesoscale dynamics is investigated in the western Mediterranean Sea (WMed) using a set of ROMS model simulations. The research is structured in a series of sequential stages covering the mesoscale-tosubmesoscale range, starting from a regional overview of the WMed ocean circulation and zooming in towards local processes. The mesoscale exploration is assessed in terms of the Lorenz energy cycle (LEC), which provides a quantification of the kinetic-potential energy exchanges through eddymean flow interactions. The sources of eddy kinetic energy are analyzed by applying a regional formulation of the LEC to 18 years of the ROMSWMED32 numerical simulation at eddy-resolving resolution (3.5 km), which allows identification of whether the energy exchange between the mean and eddy flow is local or nonlocal. The patterns of energy conversion between the mean and eddy kinetic and potential energy are estimated in three subregions of the domain: the Alboran Sea, the Algerian Basin, and the Northern Basin. Results from the LEC analysis reveal that the Alboran Sea is the most energetic region in the WMed. The spatial characterization of the energy conversion routes, together with the physical and dynamical characteristics of the area, hints at two principal submesoscale mechanisms involved in maintaining balance: topographic vorticity generation (TVG) and frontogenesis (FG). The transition toward the submesoscale is explored in the Alboran Sea by means of two nested, realistic simulations covering this region with increasing horizontal resolutions ranging from 1.5 km (WMed1500) to 0.5 km (Alb500). Unbalanced submesoscale dynamics emerge in the finer solution as the model resolution is increased. The occurrence of TVG and FG in Alb500 does not display a clear spatial nor temporal variability which facilitates an overall statistical approach. Instead, our analysis is focused on particular events of FG and TVG which are considered to be representa- tive of the Alboran Sea dynamics. TVG is explored and quantified using the barotropic vorticity balance equation, in which the generation of vorticity through flow-topography interaction relies on contributions from bottom stress and form drag, the latter being the principal source. FG is analyzed in a recurrent, intense density front located at the eastern edge of the permanent western anticyclonic gyre (WAG) which has a similar structure to that of the climatological Almeria-Oran front. Alb500 accurately reproduces the process of FG in this front, instigated by the straining of the mesoscale velocity field, and the generation of ageostrophic secondary circulation, exhibiting transient downwelling events reaching peak vertical velocities of O(1) km day−1 . The vertical velocity background revealed throughout the analysis of the Alb500 solution suggests that vertical motions in the Alboran Sea might stem from additional sources of perturbations in the submesoscale range, such as mixed layer instabilities, tidal effects or topographic internal waves. Exploring these mechanisms and the possible interactions among them is beyond the scope of this Thesis; planned further analysis of the Alb500 simulation using Lagrangian techniques is likely to shed light on such processes.Este trabajo ha sido financiado por el Proyecto Intramural EVOS del Consejo Superior de Investigaciones Cient íficas (CSIC 201530E067) y por la Universitat de les IllesBalears, a través de la acción especial del Govern de les Illes Balears (AAEE110/2017

Physical oceanography of the western Iberia ecosystem: latest views and challenges.

The present review is focused on the mesoscale physical processes recognized in the Western Iberia Ecosystem, complementing earlier reviews dedicated to larger scales. Recent studies support the idea that the mesoscale processes, superimposed on the larger scale variability, are the major factor controlling the ecosystem functioning in the region. A complex structure of interleaved alongshore slope, shelf and coastal currents that interact with eddies, buoyant plumes, upwelling filaments and fronts, surface layer expressions of the subsurface circulation and internal waves is revealed by the latest research. All of these contribute in different ways to have an effect on the ecosystem. The supposedly less variable winter circulation also exhibits significant mesoscale activity, in the form of eddy shedding from the poleward slope current, intermittent upwelling events and transient nearshore poleward flows. The present incomplete knowledge of this complex system presents a number of challenges and questions that must be addressed if we are to arrive at a satisfactory understanding and predictive capability for the system as a whole

Physical forcing and physical/biochemical variability of the Mediterranean Sea: a review of unresolved issues and directions for future research

This paper is the outcome of a workshop held in Rome in November 2011 on the occasion of the 25th anniversary of the POEM (Physical Oceanography of the Eastern Mediterranean) program. In the workshop discussions, a number of unresolved issues were identified for the physical and biogeochemical properties of the Mediterranean Sea as a whole, i.e., comprising the Western and Eastern sub-basins. Over the successive two years, the related ideas were discussed among the group of scientists who participated in the workshop and who have contributed to the writing of this paper. Three major topics were identified, each of them being the object of a section divided into a number of different sub-sections, each addressing a specific physical, chemical or biological issue: 1. Assessment of basin-wide physical/biochemical properties, of their variability and interactions. 2. Relative importance of external forcing functions (wind stress, heat/moisture fluxes, forcing through straits) vs. internal variability. 3. Shelf/deep sea interactions and exchanges of physical/biogeochemical properties and how they affect the sub-basin circulation and property distribution. Furthermore, a number of unresolved scientific/methodological issues were also identified and are reported in each sub-section after a short discussion of the present knowledge. They represent the collegial consensus of the scientists contributing to the paper. Naturally, the unresolved issues presented here constitute the choice of the authors and therefore they may not be exhaustive and/or complete. The overall goal is to stimulate a broader interdisciplinary discussion among the scientists of the Mediterranean oceanographic community, leading to enhanced collaborative efforts and exciting future discoveries

Model-Derived Dispersal Pathways from Multiple Source Populations Explain Variability of Invertebrate Larval Supply

Background: Predicting the spatial and temporal patterns of marine larval dispersal and supply is a challenging task due to the small size of the larvae and the variability of oceanographic processes. Addressing this problem requires the use of novel approaches capable of capturing the inherent variability in the mechanisms involved. Methodology/Principal Findings: In this study we test whether dispersal and connectivity patterns generated from a biophysical model of larval dispersal of the crab Carcinus maenas, along the west coast of the Iberian Peninsula, can predict the highly variable daily pattern of wind-driven larval supply to an estuary observed during the peak reproductive season (March–June) in 2006 and 2007. Cross-correlations between observed and predicted supply were significant (p,0.05) and strong, ranging from 0.34 to 0.81 at time lags of 26 to+5 d. Importantly, the model correctly predicted observed cross-shelf distributions (Pearson r = 0.82, p,0.001, and r = 0.79, p,0.01, in 2006 and 2007) and indicated that all supply events were comprised of larvae that had been retained within the inner shelf; larvae transported to the outer shelf and beyond never recruited. Estimated average dispersal distances ranged from 57 to 198 km and were only marginally affected by mortality. Conclusions/Significance: The high degree of predicted demographic connectivity over relatively large geographic scales is consistent with the lack of genetic structuring in C. maenas along the Iberian Peninsula. These findings indicate that the dynamic nature of larval dispersal can be captured by mechanistic biophysical models, which can be used to provid

Analysis of the risks related to the logistics of the Hazardous Materials

Today, the number of industrial enterprises producing, using, storing and transporting hazardous materials is constantly increasing worldwide. This growth is linked to the progressive demand in various sectors, which makes our world riskier because of the nature and diversity of the dangerous events that may occur. The risks incurred by the hazardous materials transport activity, in case of the occurrence of an incident that may occur and have serious consequences for persons, the environment, property, a fire as an example accompanied by a release of toxic smoke, pollution of the soil and / or water, it can lead in case of non-control of the fire or the reactivity of the goods transported to an explosion. To this purpose, it is essential to protect the health and safety of personnel and to preserve the environment from any deterioration related to the risks incurred by the Transport of Dangerous Goods (TDG) business, which presents important issues for population, state and highly urbanized areas The aim of this thesis is to propose a systemic approach to risk assessment, taking into account in a global way the risks related to hazardous materials throughout the logistics chain (transport & storage). The approach consists of using the modeling and simulation techniques of an accident, to understand the consequences generated in the various scenarios in the event of the occurrence of a hazardous materials accident. This approach will allow the presentation of an industrial safety reasoning method based on actual case studies, rather than a detailed analysis of how to prevent and protect a given hazard. In the process of assessing the technological risks associated with the Transport of Dangerous Goods (TDG), the essential step is the evaluation of the risk intensity when an accidental event occurs, which is to quantify the risks involved. effects or impacts, in order to respond quickly and prioritize relief actions for the protection of the population and the environment. The assessment of the intensity of a technological risk can be carried out using an effects model, capable of estimating the effects induced by the hazardous phenomenon from a quantitative point of view, in order to determine the geographical area of the hazard where the intensity of the risk is deemed too high. In this context, the first issue addressed in this thesis is to assess the level of risk of hazardous goods transport areas for both road and marine modes of transportation, while the second issue of assessing risks in an industrial facility fixed

An overview of the literature concerning the oceanography of the eastern North Atlantic region

An overview of the main oceanographic features of the eastern North Atlantic boundary, with emphasis toward the upper layers, is presented. The principal features discussed are: water mass boundaries; forcing by wind, density and tides; topographic features and effects; fronts; upwelling and downwelling; poleward flows; coastal currents; eddies. The occurrence and spatial and seasonal variability of these features is described in five regional sections: Celtic Sea and western English Channel; Bay of Biscay; western Iberia; Gulf of Cadiz; northwest Africa. This paper is intended to provide a base of physical oceanographic knowledge in support of research in fisheries, biological and chemical oceanography, and marine biology