bluuebunny/crossref_metadata_2025_split huggingface dataset:
Evaluation of the Ocean Circulation for the Solomon Sea Using the Regional Ocean Modeling System (ROMS)
Authors: Bento A. Rute , Coelho Henrique , Yang Chunxue 
Published: November 2019

Abstract
The Regional Ocean Modeling System (ROMS) is a free-surface, terrain-following, primitive equations ocean model and it was implemented to perform a high-resolution 10-year hindcast study of Solomon’s Sea circulation patterns. The model was executed with a resolution of 1/36°, initial conditions from HYCOM+NCODA Global 1/12° and was forced by CFSR/CFSV2 momentum, mass and heat fluxes. The model was validated by comparing the simulated temperatures, salinities and flow patterns with satellite data, Argo floats and Ship ADCP measurements. In general, the model captured the main circulation patterns and performed well for the Solomon Sea. The modelled Temperature and Salinity profiles were comparable with the observations, with some error variability in the thermocline layer, which agreed with previous studies.
Corrosion Behaviour of Cupronickel 90/10 Alloys in Arabian Sea Conditions and its Effect on Maintenance of Marine Structures
Authors: Abbas Muntazir , Shafiee Mahmood , Simms Nigel 
Published: November 2019

Abstract
The composition of seawater plays a very significant role in determining the severity of corrosion process in marine assets. The influential contributors to the general and pitting corrosions in marine structures include temperature, dissolved oxygen (DO), salinity, PH, chlorides, pollutants, nutrients, and microbiological activities in seawater. The Cu-Ni (90/10) alloy is increasingly used in marine applications such as heat exchangers and marine pipelines because of its excellent corrosion resistant properties. Despite the significant advancements in corrosion shielding procedures, complete stoppage of corrosion induced metal loss, especially under rugged marine environments, is practically impossible. The selection of appropriate metal thickness is merely a multifaceted decision because of the high variability in operating conditions and associated corrosion rate in various seawater bodies across the globe. The present research study aims to analyze the early phase of corrosion behavior of Cu-Ni (90/10) alloy in open-sea conditions as well as in pollutant-rich coastal waters of the Arabian Sea. Test samples were placed under natural climatic conditions of selected sites, followed by the mass loss and corrosion rate evaluation. The corrosion rate in the pollutant-rich coastal waters was around five times higher than in the natural seawater. A case study on marine condenser (fitted with of Cu-Ni 90/10 alloy tubes) is presented, and a risk-based inspection (RBI) plan is developed to facilitate equipment designers, operators, and maintainers to consider the implications of warm and polluted seawater on equipment reliability, service life, and subsequent health inspection/ maintenance.
Impact of High Order Wave Loads on a 10 MW Tension-Leg Platform Floating Wind Turbine at Different Tendon Inclination Angles
Authors: Milano Daniel , Peyrard Christophe , Capaldo Matteo , Ingram David , Xiao Qing , Johanning Lars 
Published: November 2019

Abstract
Floating wind technology is being developed rapidly with the aim of harvesting high-energy wind resources in medium and deep water areas, unreachable using fixed bottom solutions. Given the complexity of these systems, the interactions between the structure and incident hydro-aerodynamic forces need to be well understood. While numerous solutions are being explored, an optimal design is yet to be established within the industry.
This study explores the effects of tendon inclination on the dynamic behaviour of a 10MW tension-leg platform (TLP) floating offshore wind turbine (FOWT), and the interaction of different design solutions with higher-order hydrodynamic loading. The model was subject to an extreme sea state in order to capture second and third-order wave effects, and the nonlinear waves were generated via the high-order spectral (HOS) method. The analysis was performed using the hydrodynamic engineering tool CALHYPSO, in-house developed by EDF Lab.
Second and third order inertial hydrodynamic loads were included in the time-domain simulations in order to capture low frequency loads and ringing effects respectively. Results show that difference-frequency second order effects have a negligible impact on motions and tendon tensions of the analysed floating wind turbine model, while third order terms can significantly enhance the dynamic response of the system to extreme incident waves. While inclined-leg floater configurations presented improved motion and tendon tension responses under linear loading, the inclusion of quadratic and triple-frequency contributions showed that tendon inclination can in fact increase tension variations in the mooring lines when subject to extreme wave climates. This can lead to slacking in the mooring lines being observed more frequently in inclined-leg configurations. The results therefore suggest that neglecting third order effects, as commonly done in industry, can lead to significant underestimations of motion and tendon tension responses of tension-leg platform wind turbines.
Experimental Assessment of Vertical Shear Force and Bending Moment in Severe Sea Conditions
Authors: Horel Boris , Bouscasse Benjamin , Merrien Arnaud , de Hauteclocque Guillaume 
Published: November 2019

Abstract
Recent studies have benchmarked the prediction of wave vertical bending moment (VBM) of ship in waves [1][2], and found significant scatter among the numerical codes.
Unfortunately, experimental data in extreme waves, that are relevant to ship design, are not often easily accessible, nor completely fitted to rigorous comparison to numerical codes. Then, the improvement of numerical tools and the modelling of ship’s internal loads still requires accurate experimental data measured in steep waves (ratio wave height H to wavelength λ, H/λ = 0.1) where the ship behavior and loads are modified by non-linearities.
Thus, in order to validate simulation codes, which underlies rules requirement, and to establish criteria that makes ships safer to sail in severe sea conditions, experiments are carried out in the 50m × 30m × 5m hydrodynamic and ocean engineering tank of Ecole Centrale Nantes. A 1/65th scaled model of a 6750-TEU containership is used. The ship is moored and several combinations of wavelength and wave height are tested.
While segmented hulls are commonly instrumented with strain gauges, the present experiments are performed on a segmented hull with a 6DOF sensor located close to the amidship. This setting allows for a very stiff model which dramatically reduces the hydroelastic effects. According to previous study [1], the position of the sensor is chosen where the bending moment is supposed to reach a maximum value. The model motion is measured through a Qualisys IR tracking system and accelerometers are located on the fore and aft of the beam.
Also, each of the 9 segments is equipped with a 3DOF dynamometer to measure the hydrodynamic loads on the hull. This allows for recovering the hydrodynamic loads on the segments and then to compute the shear force and bending moment discretized all over the ship length. A comparison is therefore possible with the 6DOF sensor. Details of the computations are given in the paper.
A particular attention is paid to the reproducibility and repeatability of the tests. The innovative experimental setup and the measured data are presented in the paper. Based on previous studies [3], the effects of the non-linearities are also discussed.
Understanding the Capability of RANS Based Turbulence Models on Fully Turbulent Channel Flow
Authors: İlter Yasin Kaan , Ünal Uğur Oral 
Published: November 2019

Abstract
Fully turbulent channel flow is a very common and effective way to investigate the boundary layer flow over the flat plates. Mean flow characteristics of the channel flow can be predicted using steady Reynolds Averaged Navier-Stokes (RANS) simulations although the turbulent flow has an unsteady nature. The objective of the present study is to evaluate the predictive capability of the turbulence models, which are based on RANS decomposition, in channel flow involving smooth surfaces. The study covers the application of the Reynolds-stress based second-moment turbulence closure model and the most preferred linear eddy viscosity models to determine the mean flow characteristics. The turbulence properties were compared with the DNS data obtained from the open literature. Also, an iterative study was performed for the fine-tuning of the coefficients appearing in the Reynolds-stress turbulence model. A tuned version of the Reynolds-stress model for two different frictional Reynolds numbers (Reτ) of 180 and 590 is presented. These studies will form a basis for further computations on the channel flow with a higher Reynolds number range and different channel sections. They will also serve as the initial steps for the future experimental and computational studies that will focus on the understanding of the flow mechanism over the dimpled surfaces at Reynolds numbers (based on half channel height and mean bulk velocity) up to 2.105.
Estimating Second Order Wave Drift Forces and Moments for Calculating DP Capability Plots
Authors: Barzegar Valikchali Saeed , Anderson Mitchell , Molyneux David , Steinke Dean 
Published: November 2019

Abstract
The DP capability plot is a useful tool to show the limitations of a dynamic positioning system for ships or offshore structures under loading from wind, waves and ocean currents. At the preliminary design stage, it is desirable to use fast methods for calculating the forces and moments caused by the environment, preferably without the need for CFD simulations or model experiments. Empirical methods are available for predicting aerodynamic forces and moments, and hydrodynamic forces and moments from currents, but little is published for second order wave drift forces. Wave drift forces and moment calculations have been carried out using WAMIT, for a series of ship hulls from OSVs to VLCCs and the effects of wave direction and frequency on the Surge, Sway, and Yaw forces and moment have been studied. The presentation of the results allows the user to interpolate the resulting drift forces and moments as a function of wave direction for a given ship size. In terms of wave drift loads calculation, it is found that the very large vessels are dominant in the low frequency waves, while smaller size ships are in high frequencies. The wave frequency and direction in which maximum drift load occurs depends on the ship size.
A Sensitivity Study for Operational Availability of Offshore Wind Energy Assets
Authors: Chiachío-Ruano Juan , Hermile Mahé , Kolios Athanasios 
Published: November 2019

Abstract
The rampant growth of offshore wind energy in Europe and overseas is calling for advanced operation and maintenance simulation tools for optimal infrastructure asset management. The operational downtimes due to random failures, repair times or adverse weather conditions, greatly reduce the availability of the wind farm and therefore increase the Levelised Cost of Energy of this important source of renewable energy. This paper presents a sensitivity analysis to explore the factors influencing the most the operational availability of an offshore wind farm over a particular geographical area. The analysis is carried out using a newly developed open-access tool for operation and maintenance simulation named as “OpenO&M”. The failure rates of wind turbine components and the weather safety allowable limits for maintenance vessels emerge as critical parameters for wind farm availability, specially in remote areas.
Performance of a Two-Phase Flow Solver for the Simulation of Breaking Waves
Authors: Jin Qiu , Hudson Dominic , Temarel Pandeli , Price W. Geraint 
Published: November 2019

Abstract
Wave breaking is one of the most violent phenomena observed in air-water interface interactions. This phenomenon commonly occurs in real ship flows and is one of the main sources of underwater noise and white-water wakes. The investigation of this phenomenon is thus important in ship and ocean engineering. The performance of a two-phase flow solver is investigated for a simulation of spilling breaking waves generated by a shallowly submerged hydrofoil (NACA0024) in a uniform flow. An algebraic Volume of Fluid (AVOF) method is applied to capture the dynamic behaviour of the free surface and a standard k-ε turbulence model is selected to capture the turbulent flow around and downstream of the hydrofoil. The wave profiles, pressure and velocity contours are computed to investigate the overall flow conditions and a detailed analysis of the flow field downstream of the hydrofoil is conducted in terms of velocity components and turbulence intensities at six measurement sections. A comparison of the numerical and experimental results shows that an accurate representation of the free surface and the turbulent flow beneath it is obtained with the present numerical scheme. It is expected that the systematic documentation of the performance of the AVOF two-phase solver will enable its more accurate and optimal use for simulating ship-related flows, as well as increase awareness of its potential shortcomings for those interested in general CFD simulation of breaking waves.
Girth Weld Joints From Long Upset Pipe Ends for Improving Fatigue Strength of Offshore Oil and Gas Pipelines
Authors: Marines-Garcia Israel , Aguilar Aarón , Aguilar Ramón , Pelcastre Mauricio , Darcis Philippe 
Published: November 2019

Abstract
For special high dynamic loading applications, the structural integrity of the girth welds shall withstand stress levels that might be on the limits of the permissible defect tolerances for current production welding standards for plain pipe ends. In addition, unexpected loading conditions might take the stress limits out of safe operation, which can compromise the entire line. As a solution, the cross section of the girth weld may be increased for ensuring the strength and fatigue resistance under any loading circumstances, including strain cycles of reeling installation technique. The employment of pipes with upset ends is an excellent option for those cases. To propose this option as an alternative to current offshore solution for a Major O&G company, Tenaris developed a long upset pipe end with enhanced fatigue life. The challenges of this work included the manufacturing of very long upset ends from a medium wall thickness pipe, very tight mechanical properties difference between pipe and upset material properties, and finally a welding qualification program. The improvement of the fatigue strength of this product was highly expected.
In order to achieve all requirements, especial arrangements were performed on the upsetter machine for achieving the target upset geometry; which was previously obtained by a design of experiments technique. Then the heat treatment of the pipes was designed for obtaining the tight mechanical properties difference between pipe body and upset sections. The main outcomes of the whole development are described within this paper; which include key information of how to overcome issues that might arise during the development and production stages of upsetted line pipes. The upset ends undertake a cylindrical machining; this process provides the advantage of achieving tight dimensional tolerances in the high-low girth welding alignment. The fatigue endurance data after full scale reeling experimental test are included, as well as the numerical comparison between the strain fields of plain pipe and upset girth weld unions. The welding procedure qualified during this work is described. The results of the whole development were very satisfactory and, as expected, the fatigue strength of upset ends was higher than the plain pipe.
Hybrid Model Testing of Floating Wind Turbines: Test Bench for System Identification and Performance Assessment
Authors: Arnal Vincent , Bonnefoy Félicien , Gilloteaux Jean-Christophe , Aubrun Sandrine 
Published: November 2019

Abstract
The present study shows preliminary results of the SOFTWIND project that aims at developing an innovative experimental test bench dedicated to floating wind turbine wave tank testing. The following methodology is based on a “software in the loop” approach that combines numerical modeling with physical modeling. The originality of the experimental approach lies in the use of an innovative set of actuators located at the top of the wind turbine tower which is in charge of emulating the response of the rotor. First, results of a sensitivity analysis on the specifications of the aerodynamic forces to be emulated are presented. Low pass filtering effect in the actuation — linked to the physical characteristics of the actuators and numerical-physical loop — are first considered through fully coupled numerical simulations for different load cases including turbulent winds, misaligned wind-wave conditions and different floaters. Then, a test bench with imposed motions has been designed for the verification of communication protocols, real-time execution for the numerical model, motion and force observers and preliminary actuator model identification. Response to rising steps combined with white noise identification of the actuator with this test bench give promising results in open loop.
Hydrodynamic Performance of a Current Energy Generator Based on WIG
Authors: Wang Jian , He Guanghua , Mo Weijie , Zhang Shijun , Man Jiangtao 
Published: November 2019

Abstract
The hydrodynamic performance of a novel current energy generator is studied with consideration of the effect of Wing in Ground (WIG) by Star CCM+. The pitch and heave motions of a turbine with a 2D single oscillating wing and two parallelized oscillating wings in uniform flow are simulated, and the numerical results including the lift force, drag force and moment coefficients of the hydrofoil are calculated to analyze the hydrodynamic performance of the generator. First, the convergence studies with respect to the mesh and time step are firstly carried out by compared with the published data. Secondly, the hydrodynamic performance of the WIG-based current energy extraction is investigated, and a good performance of the current energy extraction is confirmed. Finally, the effect of boundary conditions of wing and wall on the performance of the current energy generator is investigated.
Numerical Investigation for Vortex-Induced Vibrations of Steel-Lazy-Wave-Risers: Part I — CFD Validation Against Forced Oscillation Model Test
Authors: Jang Hyunchul , Kim Jang Whan 
Published: November 2019

Abstract
Vortex-Induced Vibration (VIV) is one of the main sources of fatigue damage for long slender risers. Typical VIV assessment of risers is conducted using semi-empirical software tools with the sectional hydrodynamic coefficients derived from forced-oscillation model tests on short rigid riser sections. The Steel Lazy Wave Riser (SLWR) with buoyancy sections is an attractive concept for improving fatigue performance in deep water developments, but there is limited model test data available for the hydrodynamic coefficients on SLWR’s. CFD simulation is an alternative VIV assessment tool, once it is validated for an existing model test. It can provide accurate estimates of VIV response and help to design configurations of SLWR’s without additional model tests. The present CFD simulations are performed to validate hydrodynamic coefficients of a SLWR section. The predicted drag and excitation (lift) coefficients on both bare riser and buoyancy sections are compared to the test data with respect to oscillation frequency and amplitude.
Improving the Productivity and Sustainability of Port Management Against High Tide and Tsunamis
Authors: Takahashi Koji 
Published: November 2019

Abstract
In 2011, the National Diet of Japan passed a law to implement the policy of “International Container Strategy Ports,” which would be applied to public-built private-management system and private company financing methods to container terminals at the main ports operated by Port Management Bodies which are local governments. It would also establish the port management corporation at each port in order to improve the productivity of container terminals throughout Japan. Port management corporations have already been established at several ports such as “Kobe-Osaka,” “Yokohama-Kawasaki” and “Nagoya-Yokkaichi.” The purpose of establishing these port management corporations for container terminals is to amend the rigid port management system by local governments, and to be prepared to provide a quick response to global economic changes and the wills of cargo owners and shipping companies. Current port management corporations, however, are facing various problems of management. On the other hand, as in the cases of the tidal inundation disaster at Kansai Airport and the port area due to heavy rain in 2018, port management needs to make new capital investment to cope with the issues such as the construction to protect ground structure against high tide and tsunamis. Therefore, the author would like to first analyze the issues that current port management face, and then propose solutions and possible scenarios for improving the productivity and sustainability of port management against high tide and tsunamis.
Improving the Hydrodynamic Performance of OWC Wave Energy Converter by Attaching a Step
Authors: Rezanejad Kourosh , Gadelho Jorge F. M. , López Ivan , Carballo Rodrigo , Guedes Soares C. 
Published: November 2019

Abstract
The influence of attaching a step to the conventional shore based Oscillating Water Column device on the hydrodynamic performance has been assessed by carrying out experimental investigations. The level of the efficiency improvement in various wave characteristics and Power Take-Off damping conditions were investigated. Three different Power Take-Off damping conditions have been applied to the system and experiments were carried out for both regular and irregular wave conditions. The results obtained from the experimental study prove that the Oscillating Water Column with the attached step has substantially improved hydrodynamic performance in all the Power Take-Off damping conditions compared to the Oscillating Water Column model in uniform water depth.
An Experimental Study of Snap Loads on a Vertical Hanging Cable System
Authors: Hsu Wei-Ting , Chuang Tzu-Ching , Hsu Wen-Yang , Sharman Krish , Yang Ray-Yeng 
Published: November 2019

Abstract
Sudden snap events on mooring lines and hanging cables can cause spikes in tension, resulting in reduced safety factors during extreme events. For example, the mooring system of a floating offshore wind turbine (FOWT) can be exposed to wave-induced motions making the former vulnerable to snap type impact. Suitable criteria to define snap events are still largely unclear, making current design practices overly conservative.
To understand the underlying physics of snap loads on a mooring line system, this paper presents a theoretical development and an experimental parametric study of snap events. The effects of the nonlinearity of bilinear line stiffness and hydrodynamic drag force, as well as the weight of payload on snap events are investigated using the vertical hanging cable model. This cable model includes two springs in series and a payload. The bilinear spring model is designed to create nonlinear dynamic tension. A total of 108 tests were conducted in the wave tank of Tainan Hydraulic Laboratory. The excitation amplitude ranges from 0.01 to 0.04m; excitation time period ranges from 0.5 to 2s; the weight of payload ranges from 6.13 to 18.95N. The tests carried out in water are compared to those conducted in air. It is seen that the hydrodynamic drag force together with the small pretension could result in larger normalized tension ranges.