Towards an Improved Understanding of Green Water Exceedance at the Bow of an FPSO

2016 ◽  
Author(s):  
Riaan van ‘t Veer ◽  
Anne Boorsma
Keyword(s):  
Model Test ◽  
Weather Conditions ◽  
Model Tests ◽  
Present Problem ◽  
Green Water ◽  
Detailed Model ◽  
Water Flows ◽  
Water On Deck ◽  
Dam Breaking ◽  
Flooding Events

When a permanently moored FPSO in deep draft condition finds itself in harsh weather conditions it most likely will experience freeboard exceedance at the bow and consequently green water on deck. Knowledge about how and how much water will come onto the deck, is relevant for both a turret moored and spread-moored FPSO since both are expected to experience the most severe design conditions in head to bow quartering waves. In this paper we focus on green water phenomena observed on a Suezmax FPSO in severe head seas in the model test basin. Using an on-board video in combination with deck-mounted wave probes, green water events are recorded in detail. This provides unique insights in how the water floods onto the deck. Very different flooding phenomena are observed between different events and they can strongly deviate from a dam-breaking kind of event. Through a detailed description of three typical flooding events, the present paper improves the understanding of how green water flows onto the deck. It highlights the benefit of detailed model tests and emphasizes that new and more detailed modelling is required since the dam-breaking theory has limited value for the present problem.

The Behaviour of Tugs in Waves Assisting LNG Carriers During Berthing Along Offshore LNG Terminals

2005 ◽  
Author(s):  
Bas Buchner ◽  
Pieter Dierx ◽  
Olaf Waals
Keyword(s):  
Model Test ◽  
Weather Conditions ◽  
Model Tests ◽  
Design And Development ◽  
Test Study ◽  
Wave Conditions

For future offshore LNG terminals tugs are planned to assist LNG carriers during berthing and offloading operations. A model test study was carried out to better understand the tug behaviour in waves and to make a first step in the quantification of the related weather limits. Scale 1:35 model tests were performed in the two important ‘modes’ of a tug during this type of operation: the ‘push’ mode and the ‘pull’ mode. Realistic weather conditions were used and the tugs were working at the unshielded and shielded sides of the LNG carrier. Based on the results presented in this paper, it can be concluded that the motions of tugs in waves are significant, even in wave conditions that are considered to be mild for the berthing and offloading LNG carriers. The resulting push or pull loads may hamper these tug operations significantly. Special measures are necessary to take this behaviour into account in tug design, LNG carrier design and development of operational procedures and equipment. The paper gives insight in the typical tug behaviour in different weather conditions. One should be careful, however, to generalize the present results: with an optimised tug design and operation the tugs can be used in more severe conditions.

Green Water on FPSO Predicted by a Practical Engineering Method and Validated Against Model Test Data for Irregular Waves

2014 ◽  
Author(s):  
Rafael Vergara Schiller ◽  
Csaba Pâkozdi ◽  
Carl Trygve Stansberg ◽  
Douglas Gustavo Takashi Yuba ◽  
Daniel Fonseca de Carvalho e Silva
Keyword(s):  
Model Test ◽  
Model Tests ◽  
Irregular Waves ◽  
Green Water ◽  
Wave Impact ◽  
Irregular Wave ◽  
Beam Seas ◽  
Practical Engineering ◽  
The University ◽  
Wave Induced

This paper presents a series of numerical analyses performed with the potential theory-based Green Water engineer tool KINEMA3. KINEMA3 was designed to predict wave-induced impact loads on FPSOs in steep irregular waves, and for use in design load analysis. The purpose of the study presented herein is to validate KINEMA3 green water (deck overtopping) predictions in nonlinear irregular waves with results from model tests performed at the TPN (Tanque de Provas Numérico) laboratory at the University of São Paulo, Brazil. Comparisons are made for a selection of irregular wave cases, for two choices of anchoring conditions (free floating vessel and fixed vessel) and for three wave headings (180°, 225° and 270°: head, quartering and beam seas, respectively). KINEMA3 statistical green water predictions present a general good agreement with observations from the TPN model tests for all wave cases, headings and mooring conditions. Overall, observed trends for occurrence of green water and standard deviation/maximum of relative wave height are successfully reproduced by KINEMA3. In agreement with model test results, it is predicted that green water occurs more frequently for a free floating vessel and for beam seas. Additional comparisons between KINEMA3 predictions using different FPSO panel models (low-order and high-order models) present negligible differences with respect to green water estimates. The results presented herein demonstrate the robustness of the tool towards the prediction of green water for variable wave headings and sea states, and highlight the capability of KINEMA3 to be employed as an engineering-like tool for fast and multiple estimates of green water in early design studies. This work is a part of the research project “Green Water and Wave Impact on FPSO” carried out for and in cooperation with PETROBRAS.

On the Validity of CFD for Simulating Extreme Green Water Loads on Ocean-Going Vessels

2020 ◽  
Author(s):  
Henry Bandringa ◽  
Joop A. Helder ◽  
Sanne van Essen
Keyword(s):  
Model Test ◽  
Natural Extension ◽  
Model Tests ◽  
Water Dynamics ◽  
Green Water ◽  
Forward Speed ◽  
Maritime Industry ◽  
Cooperative Research ◽  
Wave Basin ◽  
Non Linear

Abstract The amount of green water and the associated loads that an ocean-going vessel may encounter during its service life are important aspects to consider in the vessel’s design and classification. As green water is typically a highly non-linear phenomenon, commonly the maritime industry relies on model tests to predict green water loads and their occurrence. In recent years, however, a lot of progress with Computation Fluid Dynamics (CFD) has been made in predicting non-linear flows and associated loads at a high level of accuracy. Especially in the field of wave impacts on (moored) offshore structures at zero speed, significant progress has been made and documented using CFD. A natural extension of this progress is to expand the obtained confidence in the applicability of CFD for simulating extreme wave events to applications involving vessels at forward speed. To that end, this paper presents a validation study towards the prediction of green water loading on a (typical) container vessel at forward speed by CFD. For validation, two extreme green water events were selected from a model test campaign carried out at MARIN within the context of the CRS (Cooperative Research Ships) working group ‘green water dynamics’. In these tests a KRISO Container Ship (KCS) is sailing in head seas when encountering severe green water. As CFD tool, the Cartesian-grid based Volume-of-Fluid CFD solver ComFLOW was selected. Furthermore, a deterministic approach is taken for the validation, by reconstructing the non-linear incoming wave in a high amount of detail and imposing the 6 degrees of motion of the vessel using the wave basin measurements. Time traces of the green water flow on deck and local- and global impact loads on the breakwater are presented and compared against the experimental data. Detailed visualizations of the CFD results are presented to further illustrate the obtained match with the model test results and emphasize the additional value of complementing model tests with deterministic CFD analysis.

Guidelines for CFD Simulations of Spar VIM

2013 ◽  
Author(s):  
Charles Lefevre ◽  
Yiannis Constantinides ◽  
Jang Whan Kim ◽  
Mike Henneke ◽  
Robert Gordon ◽  
...  
Keyword(s):  
Reynolds Number ◽  
Test Data ◽  
Model Test ◽  
Model Tests ◽  
Full Scale ◽  
Mooring System ◽  
Time Step ◽  
Cfd Simulations ◽  
Scaled Model ◽  
Sway Motion

Vortex-Induced Motion (VIM), which occurs as a consequence of exposure to strong current such as Loop Current eddies in the Gulf of Mexico, is one of the critical factors in the design of the mooring and riser systems for deepwater offshore structures such as Spars and multi-column Deep Draft Floaters (DDFs). The VIM response can have a significant impact on the fatigue life of mooring and riser components. In particular, Steel Catenary Risers (SCRs) suspended from the floater can be sensitive to VIM-induced fatigue at their mudline touchdown points. Industry currently relies on scaled model testing to determine VIM for design. However, scaled model tests are limited in their ability to represent VIM for the full scale structure since they are generally not able to represent the full scale Reynolds number and also cannot fully represent waves effects, nonlinear mooring system behavior or sheared and unsteady currents. The use of Computational Fluid Dynamics (CFD) to simulate VIM can more realistically represent the full scale Reynolds number, waves effects, mooring system, and ocean currents than scaled physical model tests. This paper describes a set of VIM CFD simulations for a Spar hard tank with appurtenances and their comparison against a high quality scaled model test. The test data showed considerable sensitivity to heading angle relative to the incident flow as well as to reduced velocity. The simulated VIM-induced sway motion was compared against the model test data for different reduced velocities (Vm) and Spar headings. Agreement between CFD and model test VIM-induced sway motion was within 9% over the full range of Vm and headings. Use of the Improved Delayed Detached Eddy Simulation (IDDES, Shur et al 2008) turbulence model gives the best agreement with the model test measurements. Guidelines are provided for meshing and time step/solver setting selection.

A step forward toward the high-resolution assessment of virtual water flows at the company’s scale

2021 ◽  
Author(s):  
Elena De Petrillo ◽  
Marta Tuninetti ◽  
Francesco Laio
Keyword(s):  
Water Management ◽  
High Resolution ◽  
Water Resources ◽  
Virtual Water ◽  
The State ◽  
Green Water ◽  
Blue Water ◽  
Food Trade ◽  
Water Flows ◽  
Final Consumer

<p>Through the international trade of agricultural goods, water resources that are physically used in the country of production are virtually transferred to the country of consumption. Food trade leads to a global redistribution of freshwater resources, thus shaping distant interdependencies among countries. Recent studies have shown how agricultural trade drives an outsourcing of environmental impacts pertaining to depletion and pollution of freshwater resources, and eutrophication of river bodies in distant producer countries. What is less clear is how the final consumer – being an individual, a company, or a community- impacts the water resources of producer countries at a subnational scale. Indeed, the variability of sub-national water footprint (WF in m<sup>3</sup>/tonne) due to climate, soil properties, irrigation practices, and fertilizer inputs is generally lost in trade analyses, as most trade data are only available at the country scale. The latest version of the Spatially Explicit Information on Production to Consumption Systems model  (SEI-PCS) by Trase provides detailed data on single trade flows (in tonne) along the crop supply chain: from local municipalities- to exporter companies- to importer companies – to the final consumer countries. These data allow us to capitalize on the high-resolution data of agricultural WF available in the literature, in order to quantify the sub-national virtual water flows behind food trade. As a first step, we assess the detailed soybean trade between Brazil and Italy. This assessment is relevant for water management because the global soybean flow reaching Italy may be traced back to 374 municipalities with heterogeneous agricultural practises and water use efficiency. Results show that the largest flow of virtual water from a Brazilian municipality to Italy -3.52e+07 m<sup>3</sup> (3% of the total export flow)- comes from Sorriso in the State of Mato Grosso. Conversely, the highest flow of blue water -1.56e+05 m<sup>3</sup>- comes from Jaguarão, in the State of Rio Grande do Sul, located in the Brazilian Pampa. Further, the analysis at the company scale reveals that as many as 37 exporting companies can be identified exchanging to Italy;  Bianchini S.A is the largest virtual water trader (1.88 e+08 m<sup>3</sup> of green water and 3,92 e+06 m<sup>3</sup> of blue water), followed by COFCO (1,06 e+08 m<sup>3</sup> of green water and 6.62 m<sup>3</sup> of blue water)  and Cargill ( 6.96 e+07 m<sup>3</sup> of green water and 2.80 e+02 m<sup>3</sup> of blue water). By building the bipartite network of importing companies and municipalities originating the fluxes we are able to efficiently disaggregate the supply chains , providing novel tools to build sustainable water management strategies.</p>

scholarly journals Water saving through international trade of agricultural products

2006 ◽  
Vol 10 (3) ◽  
pp. 455-468 ◽  
Author(s):  
A. K. Chapagain ◽  
A. Y. Hoekstra ◽  
H. H. G. Savenije
Keyword(s):  
Water Resources ◽  
Water Use ◽  
Virtual Water ◽  
Water Saving ◽  
Agricultural Products ◽  
Green Water ◽  
Blue Water ◽  
Water Flows ◽  
Global Water ◽  
National Water

Abstract. Many nations save domestic water resources by importing water-intensive products and exporting commodities that are less water intensive. National water saving through the import of a product can imply saving water at a global level if the flow is from sites with high to sites with low water productivity. The paper analyses the consequences of international virtual water flows on the global and national water budgets. The assessment shows that the total amount of water that would have been required in the importing countries if all imported agricultural products would have been produced domestically is 1605 Gm3/yr. These products are however being produced with only 1253 Gm3/yr in the exporting countries, saving global water resources by 352 Gm3/yr. This saving is 28 per cent of the international virtual water flows related to the trade of agricultural products and 6 per cent of the global water use in agriculture. National policy makers are however not interested in global water savings but in the status of national water resources. Egypt imports wheat and in doing so saves 3.6 Gm3/yr of its national water resources. Water use for producing export commodities can be beneficial, as for instance in Cote d'Ivoire, Ghana and Brazil, where the use of green water resources (mainly through rain-fed agriculture) for the production of stimulant crops for export has a positive economic impact on the national economy. However, export of 28 Gm3/yr of national water from Thailand related to rice export is at the cost of additional pressure on its blue water resources. Importing a product which has a relatively high ratio of green to blue virtual water content saves global blue water resources that generally have a higher opportunity cost than green water.

scholarly journals SCALE-MODEL TESTS OF A MOORED TANKER AT LEIXOES PORT WITH BREAKWATER'S EXTENSION

2020 ◽  
pp. 37
Author(s):  
Liliana Pinheiro ◽  
Hossam Abdelwahab ◽  
Joao A. Santos ◽  
Conceicao Fortes ◽  
Carlos Guedes Soares
Keyword(s):  
Physical Model ◽  
Model Tests ◽  
Scale Model ◽  
Experimental Setup ◽  
Detailed Model ◽  
Total Length ◽  
Oil Tanker

This paper describes the physical model, experimental setup and tests performed to study the motions and forces of a ship moored to the pier A at the Leixoes oil terminal, following the breakwater's extension at 300m, for different sea states. The Leixoes port layout was implemented at scale 1:80 with the detailed model similar to the prototype bathymetry and surrounding structures. The moored ship is a scale model of an oil tanker with a total length of 3.43 m and 0.135 m draft.Recorded Presentation from the vICCE (YouTube Link): https://youtu.be/ny5ByZtdjTs

scholarly journals Damages from extreme flooding events to cultural heritage and landscapes: water component estimation for Centa River (Albenga, Italy)

2018 ◽  
Vol 45 ◽  
pp. 389-395 ◽  
Author(s):  
Branka Cuca ◽  
Luigi Barazzetti
Keyword(s):  
River Estuary ◽  
Weather Conditions ◽  
Archaeological Site ◽  
Remote Access ◽  
Impact Monitoring ◽  
Medium Resolution ◽  
Ground Survey ◽  
Extreme Flooding ◽  
Flooded Area ◽  
Flooding Events

Abstract. The monitoring of hazardous events through change detection has an important role in the emergency management. Such actions can be performed shortly after the hazardous event for first rapid mapping but also over longer periods of time for recovery purposes and risk mapping. The use of medium resolution free-of-charge multi-spectral satellite imagery for purposes of flood extension and impact monitoring can be extremely valuable due to their ability to offer an “easy” and remote access to information, even in cases of extreme weather conditions, but also due to their high compatibility with GIS environments. The case study regards Centa River estuary that hosts an important archaeological site of Albenga within the boundaries of its riverbed. The authors propose a workflow that uses Copernicus Sentinel-2 data to provide the comparison changes firstly in the single relevant bands and successively in the indexes NDVI e NDWI, suitable for the estimation of water component. The results of this study were useful for observing the extension of the flooded area, to evaluate its impact on the archaeological remains and to further propose more targeted UAV-born and ground survey.

scholarly journals Seasonality Analysis of Sentinel-1 and ALOS-2/PALSAR-2 Backscattered Power over Salar de Aguas Calientes Sur, Chile

2020 ◽  
Vol 12 (6) ◽  
pp. 941
Author(s):  
Analia Delsouc ◽  
Matías Barber ◽  
Audrey Gallaud ◽  
Francisco Grings ◽  
Paulina Vidal-Páez ◽  
...  
Keyword(s):  
Temporal Frequency ◽  
Weather Conditions ◽  
Seasonal Patterns ◽  
Austral Winter ◽  
Backscatter Coefficient ◽  
Backscattering Coefficient ◽  
Episodic Events ◽  
Salt Crust ◽  
Flooding Events ◽  
Surface Crust

Seasonal changes control the development of salt crust over the Salar de Aguas Calientes Sur located in Andes Highlands, Chile. Precipitations throughout the Altiplanic winter (December to March) and austral winter (June to September) caused ponds to enlarge and surface salt crusts to dissolve driving roughness and dielectric features of the salar surface change over time. A four-year time series backscattering coefficient analysis, obtained by Sentinel 1 and ALOS-2/PALSAR-2 with 10 m of spatial resolution, demonstrated the capability of microwaves to discriminate seasonal patterns illustrated in this paper. Both sensors showed to be sensitive to changes in the surface crust due to weather conditions. Backscattered power gradually increased during the driest months as the rough salt crusts develop and decreased rapidly due to precipitations or flooding events, which lead to a smoothing appearance to radar. The high temporal frequency of acquisition in Sentinel 1 (5–13 scenes/month) allowed the discrimination among climate and annual seasonality and episodic events in the C-band backscatter coefficient. On the other hand, ALOS-2/PALSAR-2 showed subsurface changes at L-band since the salinity of the brine in the soil reduces the penetration depth of backscattered power for shorter wavelengths. Results might be useful to monitor salars with geographic and weather conditions similar to Salar de Aguas Calientes Sur.

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