Numerical analysis of floating structures for off-shore and harbour engineering

The aim of the research was to create an open source numerical model able to simulate every kind of harbour and offshore structure, fixed and floating. The code implemented was able to reproduce a physical wave tank and can be used during the design phase as an integration to physical tests. OpenFOAM was used as a starting point to develop the new code, furthermore the boundary condition IHFOAM tool was applied to generate and absorb waves. In order to reproduce deep water conditions, the code was improved with new boundary conditions and a new turbulent model. Furthermore an additional numerical restraint was implemented in the solver interDyMFOAM for representing a realistic mooring line when simulating floating structure with OpenFOAM. The new numerical tool was calibrated and validated thanks to a comparison with experimental tests. Furthermore, the way to generate coupled waves and currents was explained and shown. Results of all the tests carried out were promising; showing good agreement with theoretical values and physical tests. An application to a real study case was finally shown; a floating wind turbine was designed for an offshore area in Mazara del Vallo, (Sicily, Italy) and its response to wave loads was analysed with the new code. The real case application demonstrated the model can be helpful in the design phase and it can be used for a wide range of applications, from harbour floating piers to offshore structures. Moreover, this methodology, with active absorption, lead to reduce the domain covered by the 3-D model and to simulate the interaction between sea states and structures in competitive times and computational costs

Optimal index related to the shoreline dynamics during a storm: the case of Jesolo beach

Abstract. The paper presents an application of shoreline monitoring aimed at understanding the response of a beach to single storms and at identifying its typical behaviour, in order to be able to predict shoreline changes and to properly plan the defence of the shore zone. On the study area, in Jesolo beach (northern Adriatic Sea, Italy), a video monitoring station and an acoustic wave and current profiler were installed in spring 2013, recording, respectively, images and hydrodynamic data. The site lacks previous detailed hydrodynamic and morphodynamic data. Variations in the shoreline were quantified in combination with available near-shore wave conditions, making it possible to analyse the relationship between the shoreline displacement and the wave features. Results denote characteristic patterns of beach response to storm events, and highlight the importance of improving beach protection in this zone, notwithstanding the many interventions experimented in the last decades. A total of 31 independent storm events were selected during the period October 2013–October 2014, and for each of them synthetic indexes based on storm duration, energy and maximum wave height were developed and estimated. It was found that the net shoreline displacements during a storm are well correlated with the total wave energy associated to the considered storm by an empirical power law equation. A sub-selection of storms in the presence of an artificial dune protecting the beach (in the winter season) was examined in detail, allowing to conclude that the adoption of this coastal defence strategy in the study area can reduce shoreline retreat during a storm. This type of intervention can sometimes contribute to prolonging overall stability not only in the replenished zone but also in downdrift areas. The implemented methodology, which confirms to be economically attractive if compared to more traditional monitoring systems, proves to be a valuable system to monitor beach erosive processes and provide detailed indications on how to better plan beach-maintenance activities. The presented methodology and the proposed results can therefore be used as a basis for improving the collaboration between coastal scientists and managers to solve beach erosion problems, in locations where data are scattered and sporadic

Application of a new OpenFOAM tool to design a pilot floating wind farm offshore mazara del vallo (Italy)

A new Computational Fluid Dynamic tool, based on OpenFOAM, was implemented to reproduce a physical wave tank for offshore applications. The code has new boundary conditions for deep water wave generation, a new turbulent model and a new numerical restraint to represent realistic mooring lines in OpenFOAM. A real study case application of this tool is shown hereby: a preliminary analysis of a floating wind turbine offshore Mazara del Vallo, (Italy). The application demonstrated the usefulness and capability of the model. Moreover, with active absorption, the dimension of the numerical domain, computational costs and time of the simulations are reduced

OFFSHORE ADRIATICO Opportunità di riutilizzo delle strutture esistenti

La parola decommissioning è di origine militare e, probabilmente, fu usata per la prima volta negli anni Venti del Novecento per indicare la messa fuori servizio - ossia il disarmo - di mezzi navali, aerei e pezzi di artiglieria; l’oil&gas è stato uno dei primi settori industriali, assieme al nucleare, ad appropriarsene, qualche decennio or sono, quando si è manifestata la necessità di avviare le attività di rimozione degli impianti di estrazione offshore del Golfo del Messico divenuti oramai obsoleti. Oggi il problema del decommissioning offshore è globale considerando che nei mari che bagnano i cinque continenti ci sono oltre 8000 piattaforme fisse e almeno un migliaio di impianti mobili; diversi esperti stimano che di queste unità asservite all’industria petrolifera offshore, da oggi al 2040, oltre 2000 saranno messe fuori servizio. Il decommissioning delle piattaforme fisse viene usualmente effettuato rimuovendo integralmente le piattaforme dall’ambiente marino in cui si trovano, portandole a terra e poi demolendole o smontandole per venderne gli equipment di valore o, in qualche caso, effettuando un revamping della topside per poi riutilizzarla in altri giacimenti. In alcune regioni - ad esempio nel Golfo del Messico - i jacket, ossia le strutture metalliche di sostegno, una volta tagliate in più tronconi e rimosse sono state, in molte occasioni, adagiate sul fondo a formare reef artificiali. Si conta solamente un caso in cui una piattaforma sia stata riconvertita con una destinazione d’uso non industriale: non si 6 tratta peraltro di una piattaforma fissa, ma di un drilling rig,un impianto di perforazione mobile, trasformato alcuni anni or sono in resort con annesso diving center e che oggi si trova in Malesia; la riconversione in una struttura a vocazione turistica, è una idea affascinante, ma non priva di difficoltà ed incognite, non in ultimo dal punto di vista normativo. In questi ultimi anni sono apparsi tanti studi e proposte di riconversione, più o meno originali, segno dell’interesse che c’è nel volere esplorare possibili utilizzi alternativi, ma praticamente nessuno di questi studi ha poi trovato una effettiva realizzazione. Lo studio di Agnese Paci e Renata Archetti sul riutilizzo di una piattaforma offshore non è, come è stato in molti casi simili, un puro esercizio di fantasia, ma ha innanzitutto il pregio di avere sviluppato una proposta applicata ad un caso reale - la piattaforma Angela- Angelina installata di fronte alla costa ravennate - e che, da un punto di vista tecnico, risulterebbe realizzabile con relativa facilità. Questo studio è però andato oltre, recuperando il concetto di “isola artificiale “e proponendo una transizione verso una seconda vita post-industriale che potrebbe trovare nel turismo e nella ricerca scientifica una sintesi originale e sostenibile se supportata da uno specifico inquadramento legislativo e, non in ultimo, da investitori lungimiranti. In definitiva, la filosofia che sta alla base di questa proposta è quella che interpreta qualsiasi riconversione di un insediamento produttivo - e le piattaforme offshore lo sono a tutti gli effetti - come un caso di archeologia industriale meritevole di salvaguardia, dove il riuso adattivo esce sempre vincente quando il termine di paragone con una realizzazione ex novo è il bilancio energetico complessivo; un risultato che, in una epoca di low-carbon-economy, non può essere ignorato. L’obiettivo felicemente raggiunto nello studio è stato quindi quello di avere coniugato, anche nel settore dell’oil&gas offshore, temi apparentemente dissonanti - industria e turismo - proponendo una soluzione che, oltreché tecnicamente realizzabile, si dimostra anche sostenibile da un punto di vista ambientale, sociale ed economico

3D-numerical analysis of wave-floating structure interaction with OpenFOAM

Modelling of floating structures is a challenging task for offshore and coastal engineering purposes. Their design requires detailed knowledge in forces, flow velocities, rotations, displacements and loads. Highresolution numerical modelling allows for the study of their behavior under sea forcings, giving necessary information on the turbulent multiphase processes and induced loads. OpenFOAM is one of the code that offers a possibility to include Computational Fluid Dynamics approach into the design processing. In the present study, a floating vertical cylinder was chosen to evaluate the code capability to simulate moving bodies under waves. Tests reproducing the free decay were performed. Then, the wave generation tool, IHFOAM, was included to analyze the dynamics of a cylinder, moored to the bottom, under regular waves. This innovative application with OpenFOAM\uae represents the first step to develop a numerical wave tank where to study wave-structure interaction

Changing Dietary Habits: The Impact of Urbanization and Rising Socio-Economic Status in Families from Burkina Faso in Sub-Saharan Africa

(1) Background: Sub-Saharan Africa is experiencing the fastest urbanization worldwide. People in rural areas still have a traditional and rural lifestyle, whereas the Westernization of diet and lifestyle is already evident in urban areas. This study describes dietary habits of families in Burkina Faso living at different levels of urbanization. (2) Methods: Data on lifestyle, socio-economic conditions, health status and anthropometry were collected from 30 families living in rural villages, a small town and the capital city. A food frequency questionnaire and a 24 h recall diary were used to estimate dietary habits and macronutrients intake. (3) Results: The urban cohort showed a more diversified diet, with a higher intake of animal protein and, especially in children, a higher consumption of simple sugars. Fiber intake was significantly higher in the rural and semi-urbanized cohorts. As expected, overweight and obesity gradually increased with the level of urbanization. In semi-urbanized and urban families, we observed coexistence of under- and over-nutrition, whereas in rural families, a portion of children were wasted and stunted, and adults were underweight. (4) Conclusions: These three cohorts represent a model of the effect on diet of rural-to-urban migration. Rural diet and traditional habits are replaced by a Western-oriented diet when families move to urbanized areas. This dietary transition and increased socio-economic status in newly developing urban areas have a major impact on disease epidemiology, resembling the past evolution in Western countries

Divergence Between Clinical Trial Evidence and Actual Practice in Use of Dual Antiplatelet Therapy After Transient Ischemic Attack and Minor Stroke

Background: Randomized controlled trials (RCTs) proved that short-term (21-90 days) dual antiplatelet therapy (DAPT) reduces the risk of early ischemic recurrences after a noncardioembolic minor stroke or high-risk transient ischemic attack (TIA) without substantially increasing the hemorrhagic risk. We aimed at understanding whether and how real-world use of DAPT differs from RCTs. Methods: READAPT (Real-Life Study on Short-Term Dual Antiplatelet Treatment in Patients With Ischemic Stroke or TIA) is a prospective cohort study including >18-year-old patients treated with DAPT after a noncardioembolic minor ischemic stroke or high-risk TIA from 51 Italian centers. The study comprises a 90-day follow-up from symptom onset. In the present work, we reported descriptive statistics of baseline data of patients recruited up to July 31, 2022, and proportions of patients who would have been excluded from RCTs. We compared categorical data through the χ² test. Results: We evaluated 1070 patients, who had 72 (interquartile range, 62-79) years median age, were mostly Caucasian (1045; 97.7%), and were men (711; 66.4%). Among the 726 (67.9%) patients with ischemic stroke, 226 (31.1%) did not meet the RCT inclusion criteria because of National Institutes of Health Stroke Scale score >3 and 50 (6.9%) because of National Institutes of Health Stroke Scale score >5. Among the 344 (32.1%) patients with TIA, 69 (19.7%) did not meet the RCT criteria because of age, blood pressure, clinical features, duration of TIA, presence of diabetes score <4 and 252 (74.7%) because of age, blood pressure, clinical features, duration of TIA, presence of diabetes score <6 and no symptomatic arterial stenosis. Additionally, 144 (13.5%) patients would have been excluded because of revascularization procedures. Three hundred forty-five patients (32.2%) did not follow the RCT procedures because of late (>24 hours) DAPT initiation; 776 (72.5%) and 676 (63.2%) patients did not take loading doses of aspirin and clopidogrel, respectively. Overall, 84 (7.8%) patients met the RCT inclusion/exclusion criteria. Conclusions: The real-world use of DAPT is broader than RCTs. Most patients did not meet the RCT criteria because of the severity of ischemic stroke, lower risk of TIA, late DAPT start, or lack of antiplatelet loading dose. Registration: URL: https://www. Clinicaltrials: gov; Unique identifier: NCT05476081