bluuebunny/crossref_metadata_2025_split huggingface dataset:
Evaluation of a Hybrid Representation to Model the Wind Turbine, Platform and Mooring Lines in the Analysis of Floating Offshore Wind Turbines
Authors: de Araújo Neto Elói Daniel , Mendez Rodriguez William Steven , Nogueira Correa Fabricio , de Souza Leite Pires de Lima Beatriz , Pinheiro Jacob Breno , Ortega Arturo 
Published: December 2020

Abstract
This work presents and evaluates a hybrid methodology for the analysis of FOWT, taking advantage of the SITUA-Prosim code developed by LAMCSO/COPPE/UFRJ, and the NREL FAST code. SITUA-Prosim has been originally developed for the coupled analysis of floating platforms for oil production. It fully couples a validated hydrodynamic model, which represents the hull motions, with a full nonlinear dynamic Finite-Element based structural model, which represents mooring lines and risers.
The first step of the methodology is to employ the FAST code to generate time-series of forces on the bottom of the tower. These forces are then applied as input for an analysis with the SITUA-Prosim code where the platform and mooring lines are fully coupled, the latter being represented by a full nonlinear dynamic FE model. This may be considered as a “hybrid” methodology since it uncouples the platform motion response from the forces from the wind turbine, but couples the platform motions with the nonlinear dynamic structural response of the mooring lines.
The methodology is applied to analyze the OC4 DeepCwind semisubmersible, taking different wind velocities, and evaluating the influence of the elastic behavior of the blades on the global motion and line tension responses. The results are compared with a standard procedure where the whole system is analyzed entirely by the FAST program.
Due to its simplification, this hybrid methodology can be employed for preliminary or intermediate design stages. The main goal of the studies presented here is to comprise an initial step toward a full integration between the Prosim and FAST programs. In future works a full coupling between the wind turbine forces and the platform motions will be implemented.
High Temperature Flowline Thermal Design Using Rotating Buoyancy Modules
Authors: Yu Shenkai , Chapman Tracey , Rich Sharon , Harbison Austin 
Published: December 2020

Abstract
A rotating buoyancy modules (RBM) system was developed as an improvement to the non-rotating buoyancy from the collaboration between a major oil company and Trelleborg Offshore. In this system, a finned external shell rotates around an inner core strapped to pipeline. The rotating buoyancy reduces berm build-up, decreases friction for pipe-soil interaction, and ensures the robustness of buckling mitigation for HPHT thermal design. In the contrast, for a non-rotating buoyancy module, seabed soil berms can build up after the initial flowline lateral movement which can limit further lateral movement. As result of berm build-up, the effectiveness of non-rotating buoyancy modules to control pipeline buckling reduces.
RBM was applied for the first time in a tie-back flowline for a Gulf of Mexico (GOM) deepwater development project. In this paper, flowline thermal design using RBM for the project is presented.
The project field conditions that impacted the tie-back flowline design included existing crossings and limited space for subsea structures and flowlines. The pipe-seabed interaction and RBM-seabed model is presented along with the axial and lateral friction parameters used for peak and large displacement on normal pipe sections and RBM sections. The main loads for the flowline were from the operational conditions in term of temperature and pressure profiles. Lateral buckling mitigation results include the RBM location configurations, buckling locations, effective axial forces and von Mises stresses. Recommendations for situations when RBM should be used for high temperature high pressure thermal design are presented.
Sensitivity Analysis in Parametric Rolling of a Modern Cruise Ship Using Numerical Simulations in 6-DOF
Authors: Düz Bülent 
Published: December 2020

Abstract
Parametric roll is a nonlinear phenomenon that can result in large roll angles coupled with significant pitch motions. These motions might induce large loads on the ship structure, and compromise the safety of the crew and the cargo. The severity of the motions might reach to such levels that capsizing might occur. In this study sensitivity analysis in parametric rolling of a modern cruise ship is investigated using numerical simulations. Several parameters were considered as sources of uncertainty such as the combined effect of GM and roll radius of gyration, roll damping, ship speed, and fin characteristics. In terms of fin characteristics, fin angle rate and maximum angle, fin area and aspect ratio, and fin gains were investigated. Additionally, the non-ergodicity of parametric roll was studied as well as the effect of simulation duration on the statistics of parametric roll. The simulations were carried out with a hybrid time-domain seakeeping and manoeuvring code. The time-domain code was used in combination with a strip-theory based frequency-domain program in order to calculate diffraction and radiation forces as well as added-mass. The time-domain code was able simulate the dynamic behavior of a steered ship in 6-DOF, where the motions can be large up to the moment of capsize.
Impact of a Wind Turbine Blade Pitch Rate on a Floating Wind Turbine During an Emergency Shutdown Operation
Authors: Louazel Pauline , Son Daewoong , Yu Bingbin 
Published: December 2020

Abstract
During the shutdown of a wind turbine, the turbine blades rotate from their typical operating angle to their typical idling angle (approximately 90 degrees) at a specific speed, called the blade pitch rate. This operation leads to rapid loss of thrust force on the turbine resulting in a corresponding heel response of the floating structure. This rapid variation of loads at the turbine also leads to large nacelle accelerations which are transferred to the bottom of the tower and consequently to the floating structure, making the turbine shutdowns, and specifically emergency shutdowns, of significance in the design and certification of the turbine, tower and floating structure.
In case of an emergency shutdown (for instance due to a grid loss), the blades typically pitch from 0 degree to 90 degrees in approximately 20–35 seconds, whereas this time period can be more than 100 seconds in the case of a normal shutdown [6]. For fixed-bottom wind turbines, increasing the blade pitch rate leads to an increase of instantaneous loads at the nacelle and tower, leading to the emergency shutdown pitch rate being usually chosen to be as low as possible. In the case of a floating wind turbine, however, water/platform interaction effects such as wave induced damping on the floating platform, challenge this approach. Indeed, increasing the blade pitch rate can increase the effect of wave-induced damping on the floater and therefore reduce the loads on the overall structure. On the other hand, reducing the blade pitch rate during an emergency shutdown can reduce this damping effect and increase those loads, meaning that an optimal blade pitch rate for a fixed bottom turbine is not necessarily optimal for a floating wind turbine.
This paper will examine the behavior of a floating offshore semi-submersible platform, the WindFloat, during turbine shutdown operations, with an emphasis on the blade pitch rate during an emergency shutdown.
Subsea Pipeline Engineering Challenges in Sand Wave Area: The Lufeng Feed Project
Authors: Jun Huang , Xing Zou , Liwei Li , Igland Ragnar Torvanger , Zhenhui Liu , Bijker Romke 
Published: December 2020

Abstract
Lufeng oilfields are located in the Pearl River Mouth Basin, South China Sea, where significant sand wave is located. The water depth of the area is 140 to 330 m. Sand waves are present around LF15-1. A study on the sand waves is required to assess the impact of the sand waves on the pipeline design. Due to its special seabed characteristic, it is challenging for the subsea pipeline engineering. This paper presents the Lufeng sand wave pipeline project on general basis. Collect and review available information including metocean, bathymetric data and soil data and carry out general morphological analysis for the project area including seabed erodibility assessment and analysis of sediment transport potential. Identify morphological features and bed forms in the project area and analyze characteristics of the sand waves. Sand wave migration and mobility are predicted and the pipeline route (least dredging/trenching and least free spans) is optimize considering on-bottom stability, in-place strength, global buckling and installation. Determine burial (dredging/trenching) requirements assuring pipeline stability/integrity. The main challenges faced are summarized, some preliminary results are also presented. Discussions about the solutions are also included, which may shed light to similar projects.
Prediction of Performance of Tip Loaded Propeller and its Induced Pressures on the Hull
Authors: Kim Seungnam , Kinnas Spyros A. 
Published: December 2020

Abstract
In this paper, a boundary element method (BEM) is applied to a tip loaded propeller (TLP) to predict its open water characteristics and induced hull pressures under fully-wetted and uniform inflow. Tip of a TLP blade has a winglet-like tip plate on the pressure side to improve the overall propeller efficiency over the traditional open tip propellers by preventing circulation loss toward the tip region. TLPs are also used to reduce the tip vortex strength and thus free from the trade off the propeller efficiency against the cavitation performance; therefore, predicting their performance early in the designing stage via numerical applications can provide the initial knowledge on the loading distributions and cavitation performance. In the present method, the trailing wake is first aligned using the full wake alignment (FWA) scheme by aligning the wake surface to the local stream in order to satisfy the force free condition. The FWA is shown to improve the open water characteristics of the TLPs compared to the simplified alignment scheme that ignores the details of the flow behind the trailing edge due to the simplicity of the method. Afterwards, a pressure-BEM solver is used to solve for the diffraction potentials on the hull and estimate the propeller-induced hull pressures. In this case, both the FWA and the unsteady wake alignment scheme (UWA), which considers the time dependency of the problem, produce the same results as the testing flow is assumed to be uniform. This paper briefly introduces the model TLP, proper ways to consider the viscous effect on the blade surface, wake alignment scheme, and the pressure-BEM solver. Then, the predicted open water characteristics of the benchmark TLP and its induced hull pressures are compared to the experimental data, as well as the results from unsteady full-blown Reynolds-Averaged Navier-Stokes simulations for validations of the numerical predictions.
Detailed Study on the Behavior of Ships in Very Short Waves
Authors: Yokota Saori , Kuroda Mariko , Fukasawa Ryohei , Ohba Hiroki , Tsujimoto Masaru 
Published: December 2020

Abstract
Considering the sea conditions in which a large ship encountered in operation, the ship’s behavior in very short waves is important. However, the evaluation of the ship performance in very short waves was not enough validated by tank tests. Because it is difficult to generate waves with enough accuracy due to the performance of the wave generator.
In this paper, it is shown that tank tests of added resistance in the regular waves including the very short waves are conducted in the Actual Sea Model Basin at National Maritime Research Institute, MPAT for DTC container ship and accurate results are obtained. The test results are compared with the benchmarks published by SHOPERA (Energy Efficient Safe SHip OPERAtion). In addition, three curves of the added resistance in the regular waves based on the results of the tank test are compared and the sensitivity analysis of energy efficiency is discussed. In the sensitivity analysis, the performance simulator for ships in actual seas (VESTA) is used, and a comparison is carried out for the fuel consumption calculated from the frequency response of each added resistance in waves. As a result, it is found that the tendency in added resistance in very short waves affects the fuel consumption and the decrease of ship speed.
A Coupled SPH-FEM Solver for Modeling Surface Effect Ship (SES) Bow Seal Dynamics
Authors: Gilbert John , McCue Leigh 
Published: December 2020

Abstract
The life of Surface Effect Ship (SES) bow and finger seals are often short-lived due to a combination of environmental effects and dynamic loading due to high-speed operation. Improving SES seal robustness requires a deeper understanding of the dynamics and loads seen by SES skirt seals during operation. In this work, we present the results of a validation study performed for a coupled, smoothed particle hydrodynamics (SPH) - finite element method (FEM) solver developed to study fluid-structure impact and free-surface flow interaction with hyper-elastic structures. This work continues and extends the earlier coupled SPH-FEM approach of Yang et al. [1]. Numerical predictions for skirt seal displacement are compared against the experimental observations of Zalek and Doctors performed by the Marine Hydrodynamics Laboratory at the University of Michigan [2].
A New Rigid Jumper VIV Response Model: JIP Development
Authors: Nair Aravind , Jaiswal Vivek , Fyrileiv Olav , Vedeld Knut , Zheng Haining , Huang Jerry , Tognarelli Michael , Goes Rafael , Bruschi Roberto , Bartolini Lorenzo , Vitali Luigino 
Published: December 2020

Abstract
Recognizing the need to address the challenges associated with the VIV assessment of rigid jumpers, a joint industry project (JIP) was launched in December 2014. The JIP was based on the model test data supplied by ExxonMobil. Through the JIP study, measured responses from tow tests were used to develop new response curves for jumper systems and compared against the existing DNV GL-RP-F105 curves.
This paper presents details of the validation of model test data; processing of test data for response curve development; classification and interpretation of jumper response and; the two new response models developed for VIV assessment of rigid jumper systems.
The response model developed through the Jumper VIV JIP forms the first of its kind for the VIV of non-straight (complex) pipe systems.
Experimental Investigation on Hydrodynamic Effectiveness of a Wave Energy Converter Using Floating Breakwater
Authors: Peng Wei , Ma Junwei 
Published: December 2020

Abstract
Wave energy is favored by more and more people because of its wide distribution, pollution-free, renewable and many other advantages. Among numerous wave energy converting devices, the converters using floating breakwaters are recognized to be quite promising as the construction and maintenance cost can be shared. In this study, a shoreline wave energy converter (WEC) is proposed which consists of a floating breakwater arranged along the wave direction and restricted to only have vertical degree of motion. Making use of the motion of breakwaters, a dynamo is able to convert the wave power to electricity. At the same time, the incoming waves can be attenuated due to the complex interaction between waves and the floating structure. A scale model was built in the laboratory at Hohai University, and then employed to investigate the performance of developed wave energy device. In the physical model, dynamos and resistance were employed as the power take-off (PTO) system, and the instantaneous output power could be calculated using the measured data. Experimental results show that the resonance state of float plays an important role for the wave energy extraction, and the hydrodynamic efficiency of the device under the resonance state can be up to 41.8% for single breakwater, counting in the internal energy converted by the dissipative force. When subjected to shorter waves, the PTO damping encourages the wave reflection; whereas, more wave energy is dissipated or transformed to power for longer waves. Meanwhile, the PTO damping is also a negative factor for the wave overtopping reduction as the motion of float may be restrained considerably. Last but not the least, the PTO load is proved to be a significant parameter for the optimization the output power, and a strategy must be found to achieve the best power conversion under the dominant wave conditions.
Gulf of Mexico Hurricane Single Event Fatigue Method for Riser Analysis
Authors: Mesa Jose D. , Santala Markku J. 
Published: December 2020

Abstract
Deepwater steel catenary risers (SCRs) are designed considering strength under extreme loads and long-term fatigue of the riser from installation through the full range of conditions anticipated over the service life of the riser. Short-term single event fatigue is also checked to ensure that a single extreme storm or current event does not consume an excessive amount of fatigue capacity. For Gulf of Mexico SCRs, single event fatigue can be a governing case for the riser hang-off. The requirement imposes a relatively modest number of higher stress range cycles and may bias the selection of the hang-off option (titanium, steel, and flex joints) since the three common choices have widely different sensitivity to this case.
Assessing a single event hurricane is problematic because the evolution of storms which generate an extreme 100-year significant wave height at a site can vary considerably from storm-to-storm. Simplistic representations of the extreme hurricane event could lead to either non-optimal hang-off option or a unconservative design. This study documents a response-based analysis simulating fatigue damage accumulated in differing risers over a broad set of extreme hurricanes. The extreme hurricanes are gathered from hundreds of years of hindcast storms to develop a statistical assessment of the amount of damage accumulated per event. Since the response-based analysis would be cumbersome in the design process, a simplified method benchmarked to the response-based analysis is proposed for design. The simplified method consists of accumulating fatigue damage from multiple seastate cases that are already developed to assess riser strength.
Coupling Response Analysis of Deep-Water Pipeline Based on Rapid Regulation of Stinger Radius
Authors: Ma Gang , Yang Jie , Wang Hongwei , Zhang Zizhao 
Published: December 2020

Abstract
High strain/stress is easy to occur in the overbend section of S-lay pipelines which are supported by stinger, leading to excessive deformation and buckling failure of the pipelines. In order to ensure the safety of pipelines and evaluate the maximum laying capacity of the pipelay vessel in 1600 meter, this paper uses the curvature radius method to automatically adjust the four angles and roller positions of the articulated stinger fixed on the pipelay vessel, then analyzes the pipeline strain and effective tension in static configuration and finally calculates the timedomain coupling response by establishing a nonlinear contact model of the pipelay vessel, stinger and pipelines. The adjustment speed, which is based on the curvature radius method using Python to call OrcFxAPI, is efficient remarkably. The results show that the stinger radius and roller locations are the major influential factors on the pipeline strain and anchor positions affect the detachment point strain of pipelines on overbend section. The static and dynamic strains of the overbend section are less than 0.25% and 0.305% respectively, which meet the DNV specifications.
Numerical Study of Large Pendulum Ice Impact Loads
Authors: Andrade Sthefano L. , Quinton Bruce W. T. , Daley Claude G. , Gagnon Robert E. 
Published: December 2020

Abstract
The large pendulum ice impact experiments performed at the Memorial University of Newfoundland recorded pressure distributions using a novel high-fidelity measurement device, the Impact Module, which is capable of fine spatial and temporal resolutions — effectively 2 cm2 at 500 Hz. These experiments achieved impact energies approaching 29 kJ, velocities of 4.7 m/s, and loads reaching 620 kN. The data obtained by the device are unique, as the Impact Module is capable of recording ice pressure data with both high spatial and high temporal resolution over a large contact area. Until recently, there was no ice load measurement technique capable of excelling in all these aspects. This work aims to study the simulation of a numerical test panel model under the action of the loads measured during the ice impact experiments. This is done by using a non-linear numerical model with explicit time integration capable of simulating the dynamic transient ice loads and comparing their effects to a quasi-static approach.
Analysis of a Floating Wave Energy Converter With Hydraulic-Mechanical Power Take-Off Using WEC-Sim and SIMSCAPE
Authors: Chandrasekaran Srinivasan , Sricharan V. V. S. 
Published: December 2020

Abstract
A novel multibody ‘self-reacting’ floating wave energy converter, which constitutes a set of ‘bean’ shape tubular floats which pitch relative to the central spar (CS) resulting in net heave, is introduced in the present study abbreviated as BFWEC. The frequency-domain modeling is performed assuming potential wave theory (PWT) to obtain the fundamental building blocks viz., hydrodynamic parameters of BFWEC. The unique configuration of BFWEC with a set of four floats around CS projects it to be a novel attribute. The relative motion between CS and floats is enabled using a connecting frame and the hinge joint to each bean float. Time-domain wave-WEC interactions, along with free-decay tests, are modeled and conducted using a highly established and reliable open source MATLAB-Simulink module called WEC-Sim (Wave Energy Converter SIMulator). The CS of six degrees BFWEC with a dominant heave degree is first restricted to be fixed and later enabled to three and six degrees of freedom (D-o-F) to understand the influence of its compliance. The device is restrained and kept in position by fastening four tethers (taut mooring) to the CS by coupling it to a lumped mass stand-alone mooring line feature known as MoorDyn. A hydraulic-mechanical Power take-off (PTO) unit is coupled with BFWEC in SIMSCAPE to understand its overall performance characteristics, which is later compared with linear damping virtual PTO. The performance ratio of the device is then obtained under 0° and 45° regular waves. The critical outcome of the research is to establish a robust green channel by promoting wave energy extraction in the sea states of the Indian sub-continent with a unique and suitable design.