bluuebunny/crossref_metadata_2025_split huggingface dataset:
An Improved Interface Coupling Computational Fluid Dynamics With Potential Theory-Based Wave Descriptions
Authors: Pakozdi Csaba , Gutsch Martin , Sajan Joseph C. , Fouques Sébastien 
Published: August 2024

Abstract
This study employs the Steady Surface Gravity Wave (SSGW) theory and the periodic High-Order Spectrum (HOS) method to define the wave environment. Unlike traditional streamfunction wave theories, SSGW theory has the advantage of being valid across all water depths. This method allows for the simulation of nonlinear high-order waves with a steepness beyond what is achievable with 5th-order Stokes wave theory, and it also enables simulations in shallow water using the same theory.
A novel technique has been developed to reduce the computational cost of generating wave kinematics in Computational Fluid Dynamics (CFD) simulations. The key innovation in this technique is using bi-cubic interpolation to calculate velocity from the velocity potential, resulting in significant reductions in data volume. A similar technique is applied to link the HOS solution with CFD simulations. The commercial CFD software STAR-CCM+, used in this study, is based on the finite volume method with a segregated flow solver, using the multiphase Volume Of Fluid (VOF) model offering different motion modeling capabilities.
Verification studies employ regular waves, beginning with validating the SSGW interface by comparing it to the inbuilt Fenton’s Stokes 5th-order wave theory and the 5th-order Cnoidal wave theory. This assessment is conducted in both standing and moving frames. Additionally, regular waves defined by HOS are coupled with CFD. Both interfaces demonstrate high efficiency in terms of computational cost and a substantial reduction in the required data volume at the HOS interface.
Experimental Investigations on a Highly Flexible Submerged Structure in Waves
Authors: León Hernando Ignacio , Kosleck Sascha , Black Suzanne 
Published: August 2024

Abstract
In the wave tank facilities at the Technical University of Berlin, a series of comprehensive experiments were conducted to evaluate the feasibility of an innovative offshore fish cage design. This pioneering structure comprises several distinct cylindrical sections, each fully submerged and constructed from highly flexible membranes and fish netting. The different sections are fixed with a flexible but more rigid structure. This model is used to determine the feasibility of a full-scale model, that due to its large dimensions and near-the-surface operation, will be subjected to heavy responses and forces in demanding sea states.
The experimental setup consists of a motion capture system, that coupled with other sensors such as force gauges, allowed to track and evaluate the motion of the submerged structure as well as the wave hydrodynamical loads that it was subjected to. The primary objective of this experimental campaign was to evaluate the dynamic response of this flexible body to various wave conditions, encompassing both single regular waves and wave spectra. Different angles of attack of the body were tested with the aim of being able to cover as much variety of responses of the body as possible. Finally, the research assesses the applicability of conventional rigid-body motion analysis techniques, such as the response amplitude operator to this intricate flexible system. This paper presents the first results of what will be an in-depth analysis of these body motions in waves. Identifying, as a result, the heave motion of the mentioned underwater flexible body.
The Effect of Directional Spreading on Extreme Sea State Response for Floating Wind Turbines
Authors: Moalemi Aref , H. Wagner Mathilde , Aliyar Sithik , Ghadirian Amin , Jensen Bjarne , Bredmose Henrik 
Published: August 2024

Abstract
Empirical investigations have consistently demonstrated the multi-directional nature of actual ocean waves, a phenomenon that has been paid relatively limited attention in the research field of floating wind turbines. The present study seeks to reduce this knowledge gap by experimentally investigating the response of a novel 15 MW floating wind turbine design when subjected to multi-directional wave conditions.
The experimental work was carried out in the deep water basin at DHI A/S (DHI), at a scale of 1:40. In this investigation, the wind turbine rotor was simplistically modeled as a point mass, allowing for a focused examination of the hydrodynamic performance of the floater and mooring system.
The investigation of the concept’s behavior involved wave-only tests for irregular multi-directional waves with two spreading angles and across several sea states. The effect of swell waves was also examined through standalone tests as well as the combined motion response when they were superposed with directionally spread wind wave spectra.
While the effects of directional spreading and swell are well understood for small amplitude waves, the nonlinear interactions and load effects are less explored in the literature. The study therefore also covers severe wave conditions, both in terms of long sea state realizations and three-dimensional focusing waves. For all tests, the low-frequency response that is outside of the linear wave spectrum has special interest, since the natural frequencies of the floating structure are placed here. The outcomes of the experiments are presented through comparison of time series, power spectra, exceedance probability plots, and harmonic separation.
Extraction of Ship Collision Avoidance Patterns From AIS Data
Authors: Vijayakumar Akash , Singh Amar Nath , Somayajula Abhilash 
Published: August 2024

Abstract
The maritime industry faces constant challenges in preventing ship collisions and ensuring adherence to the Convention on the International Regulations for Preventing Collisions at Sea (COLREGs). This paper presents a comprehensive analysis of ship collision avoidance patterns utilizing Automatic Identification System (AIS) data. By examining AIS data parameters, including vessel speed, course, heading and the dynamic change in position, crucial insights into the avoidance of collision can be extracted. In this paper the encounters are extracted from the AIS data collected near Los Angeles Port. The raw data is preprocessed and visualised in a relative distance domain from the own ship. The encounters are filtered using a collision risk model and the encounter situations are labeled and classified into multiple classes using GRU-RNN deep learning technique.
Design and Motion Analysis of a Floating Water Channel Platform With Wave Energy Converters
Authors: Kim Jeongrok 
Published: August 2024

Abstract
This study performed stability and motion analysis for the basic design of a floating water channel platform (FWCP). This structure has a Y-shaped and is equipped with three wave energy converters (WECs). Such a system enhances the wave energy capture through reflection, incident wave energy collection, and fluid resonance in a closed region. The challenge is to ensure the stability and lies in accurately predicting the motion of the platform owing to fluid resonance. Thus, this study proposed four models to design a platform, and evaluated stability according to large angle through GZ curve. In addition, the motions of the platform were analyzed in the frequency domain using WAMIT and OrcaWAVE commercial codes, and compared with the model experiment results. The motion of the platform was found to be slightly overestimated at the fluid resonance frequency. Thus, further research is necessary to obtain a more accurate estimate.
Filter Units for Cable Stabilisation: The Effect of Fill Material and Volumetric Filling Ratio on Performance
Authors: Griffiths Terry , Li Frank , George Christo , Draper Scott , Clayton Jay , Pistani Fabrizio , An Hongwei , White David 
Published: August 2024

Abstract
Fiter units (sometimes called rock bags) are a very popular solution to improve the stability of subsea cables and cable protection systems (CPS) in the offshore wind industry. They are easily filled quay-side from local rock quarries and installed from vessels that are already mobilized as part of a windfarm construction spread. However, very limited data and research has been presented on the hydrodynamic properties and stability limit states for these mesh bags. No prior known literature describes the influence of filter material properties on their lateral resistance and stability, especially in the typical case where they are placed over a cable and are subjected to external loading from the cable or CPS.
This paper presents results from a parametric study involving scaled physical model tests at scale factor of around 1:10. The tests explore the performance of the bags when filled with different materials to different levels of filling. The results show that bag material and filling level have strong influence on the filter unit and cable stability due to their strong influence on the filter bag weight distribution between the cable and the adjacent seabed. Empirical models for use in engineering design are proposed based on the experimental data.
Ultra-Deep Drilling Wellbore Temperature Model Considering Thermophysical Properties of Different Lithology
Authors: Yao Xuezhe , Song Xianzhi , Zhou Mengmeng , Xu Zhengming , Cui Yueqi , Wang Haobo , Zhu Zhaopeng , Duan Shiming 
Published: August 2024

Abstract
Deep and ultra-deep drilling encounters high-temperature and high-pressure formation, and the state of wellbore flow and heat transfer is complicated, so the wellbore temperature is difficult to describe accurately. The conventional wellbore-formation heat transfer model holds that the formation lithology is uniform and the thermophysical parameters are constant value. However, a variety of lithologies are drilled during the drilling, and the thermophysical parameters of the formation vary with lithology and temperature. In this paper, a wellbore-formation heat transfer model of the ultra-deep well is developed by considering the thermophysical properties of different formation lithologies. A mathematical model of wellbore-formation heat transfer is constructed based on the law of energy conservation. Then the lithology of the formation is extracted, and the thermophysical parameters matrix of the lithology is constructed, to be embedded into the heat transfer mathematical model. Finally, the finite difference method is used to solve the mathematical model. The real data of an ultra-deep well is used to verify the model. The results show that the error between the predicted results of the model and the measured is only 3%. The wellbore-formation heat transfer model established in this paper can accurately describe the evolution law of the wellbore temperature field.
Study on Practical Fatigue Assessment Considering Hull Vibration Based on the EWP Concept
Authors: Takeuchi Takaaki , Osawa Naoki , Fukutake Natsumi , Hirakawa Shinichi , Kawajiri Yoshitaka , Yoshida Tomomi 
Published: August 2024

Abstract
Onboard multi-position hull monitoring (HM) is carried out on an 8,600 TEU container ship. The relationship between the characteristics of hull vibration (HV) superimposed stress waveforms and the fatigue damage enlargement ratio resulting from HV (Cvib) is studied. Based on this analysis, a methodology for estimating Cvib throughout the entire ship from HM data at a select few reference positions (RP) is proposed. By integrating the proposed whole-ship Cvib estimation technique with the concept of equivalent wave probability (EWP), which allows for the assessment of whole-ship fatigue damage due to wave-induced fluctuating stress (excluding HV) solely via HM data at a limited number of RP, an EWP-based comprehensive ship fatigue assessment approach that accounts for HV is developed. The effectiveness of this developed method is validated using long-term HM data. It is ascertained that the statistical attributes of Cvib throughout the entire ship can be reasonably approximated by those of the RPs with the same structural types (hatch side coaming or bottom of a cargo hold). Furthermore, it is demonstrated that the accuracy of HV superimposed fatigue damage can be improved through the estimation of Cvib’s statistical characteristics using exclusively HM data in the short seas where whipping is significantly occurring.
Local Structural Response of Concrete Shells due to Wave Impact: Calculated Responses From Measured Slamming Pressures Vs. Hydroelastic Measurements
Authors: Abrahamsen Bjørn Christian , Søreide Tore Helge , Hellan Øyvind 
Published: August 2024

Abstract
Design of concrete columns as part of offshore structures exposed to wave slamming, relies on finite element, (FE), analysis. Measured slamming forces obtained from model tests are often used as input to the analysis. This process of calculating the structural response is not straightforward, and in practical applications, it typically does not consider hydro-elastic effects, except for possibly incorporating added mass. So, how effective are these FEA calculations? Here FE analysis of a concrete shell covering a section of a monopile is carried out. The wave impact pressures used as input to the FE calculations were measured on slamming panels fixed to a circular monopile in SINTEF’s Ocean basin. The calculated utilizations are compared statistically with directly measured utilizations of elastic shells installed in the same monopile. The results show that in most cases the calculated design utilizations of the concrete shells are significantly higher than measured utilizations. Hence, the FE analysis is conservative in most cases, even though significant non-conservative simplifications were introduced in the calculation procedure.
A Practical Summation Method of Tolerances for Misalignment and SCF Calculation for Girth Welds
Authors: Hørte Torfinn , Fjeldstad Arne , Wormsen Anders , Kalvig Ragnhild Birgitte Hidle , Berg Espen 
Published: August 2024

Abstract
In conventional fatigue analysis of girth welds of risers and pipelines, misalignment with corresponding estimates of stress concentration factors need consideration. This is most important for cracks starting from the weld toe. The three most important sources for the misalignment are: i) diameter tolerances, ii) out-of-roundness (or ovality) tolerances and iii) thickness tolerances. In fatigue analysis of subsea wellhead systems, the most fatigue utilized girth welds are usually between machined components such as the wellhead or conductor housing and extension pipes or between two pipes. In this context, we have seen different industry practices on combining misalignment from the different sources of tolerances, leading to different stress concentration factors and correspondingly different fatigue lives. Both simple and somewhat complex combination methods can be rather conservative, resulting in high stress concentration factors and consequently, unacceptable low fatigue lives. There appears to be a lack of detailed guidance for combining these tolerances, and different engineers make different evaluations. We see the need for a common methodology, and in this paper, we present a practical approach, based on geometrical considerations and simplified statistical summation methods, to assess the resulting misalignment from tolerances. The applicable stress concentration factor is then calculated as a function of the misalignment using a standard formula. The method is applicable for specific tolerances provided in the relevant fabrication specification or standard. It can also be used in combination with measured so-called high/low values from the outside or inside of the pipe.
Application of the proposed methodology is demonstrated for fabrication tolerances provided in API 5L, and example results are calculated and presented as a function of pipe diameter for different pipe wall thicknesses. Results are computed for girth welds connecting a pipe to a machined component and for pipe-to-pipe connections. Different tolerances for seamless and welded pipes as given in API 5L are considered. Intermediate results are provided, such that it is transparent to see the contribution to the total misalignment from the different tolerance sources. It is likely that the method leads to somewhat lower stress concentration factors than what are most commonly used today by the industry for wellhead fatigue analyses. Although some conservatism is removed, the method is still judged to be on the conservative side which is also supported with reference to a large database of actual measured misalignments generally being less than 1 mm (OMAE2018-78408), indicating that the actual misalignment is generally well within typical fabrication requirements.
Evaluating and Optimising the Overset Solver in OpenFOAM for Complex Wave-Structure Interaction Problems
Authors: Rai Ranjodh S. , Qian Ling , Ma Zhihua , Bai Wei 
Published: August 2024

Abstract
In this paper, the latest overset mesh solver, updated in ESI-OpenCFD OpenFOAM v2212, is evaluated for two complex wave-structure interaction problems; namely, fifth-order Stokes wave interaction with a 2-D T-shaped floating body and focused wave interaction with a 3-D hemispherical wave energy converter. In particular, it is established whether the updated hole-cutting procedure improves the accuracy of solutions and reduces computational time. It is found that the accuracy of solutions for both problems are improved, but only for the T-shaped floating body case is this down to the new hole-cutting procedure. No discernible difference is made to the computational efficiency for either case. In addition, the primary bottleneck of the overset procedure in terms of efficiency is also identified with a vision of improving the overall efficiency of the solver and reducing computational time for modelling complex wave-structure interaction problems. It is found that the ‘markDonors’ function, called during the overset grid assembly procedure, is the primary bottleneck in efficiency, with the function’s parallel efficiency and scalability also shown to be poor.
The Impact of Considering the Commissioning Inspection When Defining Optimal Inspection Plans for Subsea Equipment
Authors: Maturana Marcos C. , Schleder Adriana M. , Martins Marcelo R. , de Barros Leonardo O. , Orlowski Rene T. C. 
Published: August 2024

Abstract
Cost optimization of asset management is a central issue in the offshore oil and gas strategy, and risk-based approaches has been more and more employed to assist the segment in the concretization of that goal. In this sense, the use of Risk Based Inspection by the petroleum industry has significantly increased. The inspection procedure aims mitigating the uncertainty related to the asset degradation state, enabling a better quantification of the actual damage, and, consequently, increases the accuracy of remaining life projections. Since the costs involved in offshore subsea inspections are considerable, inspection plans optimization plays a crucial role in the balance of an asset management program.
The present paper discusses the impact of considering the commissioning inspection when defining optimal inspection plans for subsea equipment. A genetic algorithm, an optimization technique inspired in the concepts of evolutionary genetics is used to obtain the optimal inspection plans. The genes are defined in terms of two variables: the type of inspection to be done and in which period it occurs, considering a finite window of opportunities for inspection occurrences. The optimization process considers a multicriteria objective function, consisting in the dimensions time, cost, and risk. Finally, the application of the proposed methodology is illustrated by means of the elaboration of the inspection plans for an Emergency Shutdown Valve and the effects of considering commissioning in the preparation of inspection plans are discussed. This study aims to contribute to improve the decision-making process concerning inspection policies.
Optimizing Northern Sea Route Transportation Times: A Comprehensive Study From Chinese Shipper’s Perspective
Authors: Gao Xinjia , Ge Wenhan , Yu Qifeng , Zhao Xintong 
Published: August 2024

Abstract
The Arctic Sea Route has long intrigued shippers and shipping companies for its potential to shorten the distance between the Atlantic and Pacific Oceans. With Arctic Sea ice melting, the Northern Sea Route’s navigational conditions have improved, revealing the growing prospects of commercial shipping. This study primarily focuses on the perspective of Chinese shippers, exploring the categories of goods that enjoy advantages on the Northern Sea Route and conducting a comparative analysis between the Northern Sea Route and the traditional Suez Canal route. Through quantitative analysis, it has been observed that as the navigational time of the Northern Sea Route increases, its position in the global maritime industry is progressively strengthening. Moreover, the article underscores the impact of transportation costs and time on profitability, providing specific cargo selection recommendations based on the effects of shortened transportation time. While emphasizing the potential advantages of the Northern Sea Route, the paper also puts forward long-term strategic recommendations to assist Chinese shippers and shipping companies in better harnessing the development opportunities provided by the Northern Sea Route and enhancing their competitiveness in the international shipping market.
Coastal Protection Measures for a Barrier Island Along East Coast of India - Physical Modelling
Authors: Mallela Mounika , Saha Nilanjan , Alluri Satya Kiran Raju , M. V. Ramana Murthy 
Published: August 2024

Abstract
Barrier islands are shore parallel sand deposits formed by the action of waves and winds and are separated from the mainland by tidal creeks, bays, and lagoons. These narrow strip of sand bars are most vulnerable to sea level rise and storm surges which are the consequences of changing Earth’s climate. As barrier islands are formed because of wind and waves, which shift according to weather patterns and local geographical features, they are most dynamic and complex in nature. As a case study, the barrier island of Sriharikota along East Coast of India stretching about 44 km parallel to pullicat lake (second largest lagoon in India) and Bay of Bengal is chosen as the study location.
From the last two decades, the shore front of the island is experiencing rapid erosion causing high risk to the infrastructure on the island. So, there is an immense need of long-term shoreline management strategies which are environmentally friendly and sustainable solutions.
The present study pertains to an experimental study on submerged rubble mound breakwater with a scaled model of 1:21 for three water depths of 0.4 m, 0.45 m, and 0.5 m. The wave heights are varied in the range of 0.05 m to 0.2 m with corresponding wave periods of 1.0 to 2.4 seconds. The performance of the submerged breakwater has been assessed by analyzing the hydrodynamic coefficients (i.e., wave reflection, transmission and loss characteristics) using two probe method. The results of the experimental study showed the significant impact of relative submergence, crest width, wave steepness and sea bed slope on the hydrodynamic performance of the structure.